GRADUATE RESEARCH SYMPOSIUM

Fellows who are in their 2nd - 5th+ year of the IGC program (admitted Spring 2022 and prior) are expected to present their work at the symposium in the form of a poster or platform presentation.  First year IGC Fellows (admitted Fall 2022 & Spring 2023) have the option to present their proposed research ideas as a poster but are not required to do so.  Fellows that are presenting their IGC capstone project have the option to also present their personal research findings in the form of a platform presentation or a poster, but are not required to do so. Fellows who have presented before should be sure to submit abstracts on new research findings that differ from their prior symposium presentation(s).  

Senior IGC Fellows, in their 3rd, 4th, or 5th year of study are strongly encouraged to give a talk.  Because we can only accommodate around 10 talks, priority will be given to those who 1) have not presented a talk at a past IGC symposium, 2) present result-rich content, 3) present content that is clearly relevant to global change issues, and 4) are furthest along in their Ph.D. program. Awards will be given for the best platform presentations.

FORMAT

Each abstract should contain:

1. Title
2. Authors and Affiliations (e.g., Department and University), presenting author denoted by an asterisk.
3. An abstract highlighting key findings and not to exceed 250 words in length

Format example:

Hopkins, W.A.*1, Dude, T.H.E. 1,2, and Sobchak, W. 1
1 Dept. of Fish and Wildlife Conservation, Virginia Tech; 2 Dept. of Interior Room Design, University of Abides

PLATFORM TALKS: presentation max time length of 12 minutes, followed by 3 minutes for Q&A.

POSTERS: maximum poster size is 40″ x 60″.  An easel and backboard will be provided.

The IGC Research Symposium is a full day event, occurring between the hours of approximately 8:30 AM to 5:00 PM. 

The agenda for the 8th Annual IGC Symposium will be posted here by early April 2023.

"At my core, I am scientist and that shines through every aspect of my life and work. I use evidence-based approaches to help college students align their professional lives with their values through one-on-one advising and professional development workshops. I support early career scientists and their mentors by creating the infrastructure underlying successful mentoring-partnerships and offering workshops focused on success in research.

I earned my PhD in biology – with a focus on stress physiology and disease in wildlife – from Virginia Tech, in Blacksburg, VA. I have a MEd in Teaching and Teacher Education from the University of Arizona and a BS in Animal Science from Cornell University."

- Laura's LinkedIn Profile

A detailed agenda and all presentation abstracts can be viewed here: 2022 IGC Symposium Detailed Agenda & Research Abstracts [PDF].

Friday, April 23, 2021  (Finalized Detailed PDF Here)

9:00 am     Welcome, by IGC Director Bill Hopkins

9:15 am     IGC Platform Presentations Session 1

10:15 am   Break

10:30 am   IGC Platform Presentations Session 2

11:30 am   Break

12:30 pm   IGC Platform Presentations Session 3

1:30 pm     Break

2:00 pm     Research Power Talks

3:00 pm     Break

3:30 pm     Introductory Power Talks from newest IGC Fellows

3:50 pm     IGC Peer Mentoring Program Overview

4:05 pm     Best Presentation Awards Announcement

Keynote Lecture by Patterson Clark

Photo credit: NPR

Patterson Clark will deliver the keynote address as part of the 7th Annual Interfaces of Global Change Graduate Research Symposium. Clark is senior graphics editor for POLITICO Pro. He previously worked for The Washington Post as science graphics editor and also wrote and illustrated the natural history column Urban Jungle. At the Miami Herald, he was on the team of journalists honored with the 1993 Pulitzer Prize for Public Service for their coverage of Hurricane Andrew and its aftermath. Before that, Patterson was an op-ed illustrator and news artist for his home-state newspaper, the Arkansas Gazette.

Clark has harvested D.C.’s exotic invasive vegetation for over twenty years, exploring its potential for use as art, food, fuel and fiber. More information about his artistic work utilizing invasive plants can be found on his website at https://alienweeds.com/index.html.

8:00 – 8:45 am  –  Poster set up; refreshments available

8:55 am  –  Welcome

9:00 – 10:25 am – Oral Presentations Session 1

10:25 – 11:40 am – Poster Session Group 1

11:40 am – 12:55 pm – Lunch

1:00 – 2:15 pm – Keynote Lecture by Patterson Clark

2:15 – 2:30 pm – Break

2:30 – 3:45 pm – Oral Presentations Session 2

3:45 – 5:00 pm – Poster Session Group 2

5:00 – 6:00 pm – Reception; Platform Awards Announced

Detailed AGENDA PDF

8:00 a.m.         Poster setup, coffee & refreshments; Fralin Hall Atrium

8:55 a.m.         Welcome; Fralin Auditorium

9:00 a.m.         Oral Presentations, Session 1; Fralin Auditorium

10:00 a.m.       Break and poster viewing

10:30 a.m.       Oral Presentations, Session 2; Fralin Auditorium

11:45 a.m.        Lunch and poster viewing; Fralin Atrium

1:00 p.m.         Oral Presentations, Session 3; Fralin Auditorium

1:45 p.m.         Poster Reception (students by posters); Fralin Atrium

3:00 p.m.         Platform Award Announcements; Fralin Atrium

3:15 p.m.         Symposium Adjourns

All IGC fellows who are in their 2nd year of PhD study or beyond are encouraged to present their work at the symposium in the form of a poster or talk. The number of oral presentations will be limited to approximately 12, and the number of posters limited to approximately 28. Senior IGC Fellows in their 3rd, 4th or 5th year of study are strongly encouraged to select to give a talk, especially if they have not done so in past symposia. Awards will be given for best talks.

FORMAT

Each abstract should contain:

1. Title
2. Authors and Affiliations (e.g., Department and University), presenting author denoted by an asterisk.
3. An abstract not to exceed 250 words in length

Format example:

Hopkins, W.A.*1, Dude, T.H.E. 1,2, and Sobchak, W. 1
1 Dept. of Fish and Wildlife Conservation, Virginia Tech; 2 Dept. of Interior Room Design, University of Abides

POSTERS: maximum poster size is 40″ x 60″.  An easel and backboard will be provided.

* denotes presenting author

Adaptive radiation in the multidimensional phenotype

Authors: Brooke L. Bodensteiner* 1 and Martha M. Muñoz 1

Affiliations: 1. Department of Biological Sciences, Virginia Tech

Adaptive radiations are considered a special case of evolutionary diversification in which a clade displays extraordinary ecological and phenotypic diversity. A common feature that unites studies of adaptive radiation is that the ecology-phenotype connection has been almost exclusively described in terms of morphology. For example, the adaptive radiation of Caribbean anoles is known for the evolution of distinct ecomorphs,, which are so-named based on the tight association between structural habitat use and morphological traits in these lizards. Despite all the of the disproportionate attention that morphological traits have received, it has also been well-recognized that physiological evolution, along a thermal gradient, is also a key aspect of the adaptive radiation of anoles. Here we test how morphological and physiological disparity compare by examining the morphology and thermal physiology of Hispaniolan anoles. Elucidating that physiological patterns of evolution do not mirror morphological patterns of evolutionary divergence. We propose that thermoregulatory behavior may be guiding these macroevolutionary patterns revealed by this study.

The invasive tree-of-heaven’s (Ailanthus altissima) relationship with understory and seedbank plant species

Authors: Brooks, R.K.* 1, Barney, J. 1, Salom S. 2, Baudoin, A. 1

Affiliations: 1. School of Plant and Environmental Sciences, Virginia Tech 2. Department of Entomology, Virginia Tech

Ailanthus altissima (Mill.) Swingle (Sapindales: Simaroubaceae), commonly known as the tree-of-heaven, was introduced to Pennsylvania in 1784 from China. Since then, this tree has spread to over 40 states. In Virginia, it is found ubiquitously in urban areas, along road ways, bordering agricultural lands, and in forests. Though Ailanthus has been shown to be associated with decreased levels of above-ground plant species richness and native species diversity in a few studies, this relationship has not been consistently found. Additionally, its impact to the seedbank (viable seeds or vegetative propagules present in the soil) has yet to be studied. To further understand this invasive tree’s impact, ten paired invaded-uninvaded sites were identified in Montgomery, Giles, and Pulaski Counties. The established canopy and understory for each plot was measured, and soil samples were collected and grown out for 5.5 months in a greenhouse. All germinating plants were identified to the highest taxonomic level possible. In total, 96 species of understory plants and 77 species of seedbank germinants were identified. Furthermore, stand size and age of each invaded plot was estimated, ranging from 2-53 years and 3-4,200m2 respectively. A preliminary analysis of the relationship between Ailanthus presence, the understory, and the seedbank is presented, followed by a discussion of its future implications.

Fish assemblage impacts of reef fisheries in tropical Brazil

Authors: Carvalho, F.M. 1, Castello, L.* 1

Affiliations: 1. Department of Fish and Wildlife Conservation, Virginia Tech

Tropical marine environments are threatened by high fishing pressure and use of nonselective fishing gears that cause the decline and even ecological extirpation of key fish populations. Such declines have the potential to change species community composition, and associated energy fluxes for whole marine communities. The goal of this research is to identify fishing gears that harm the ecosystem because they catch disproportionate amounts of non-target species and/or undersized individuals. The project will take place in the “Marine Protected Area Coast of Corals”, an area where over 100 species are regularly harvested. This includes the iconic and endangered Atlantic goliath grouper (Epinephelus itajara), which is often caught as bycatch. The data collection involves interviews with local fishers during the moment of the landing in fishing ports. An effort will be made to record the total catch per species, besides the size of each individual caught. The specific characteristics of the gears used (e.g. traps, beach seines, bottom trawlers, hand lines, spears and gill nets) will also be registered such as the length and mesh sizes of nets, size and number of hooks, etc. By identifying “harmful” gears, this project will help reverse current degradation trends by providing recommendations of gear restrictions. By evaluating our results in the context of ongoing fishing practices, our research will have direct application to fisheries management and ecosystem conservation

Predictability in the Evolution of Tetrodotoxin Resistance in Reptiles

Authors: Gendreau, K.L.* 1, Hornsby, A.D.1, and McGlothlin, J.W.1

Affiliations: 1. Department of Biological Sciences, Virginia Tech

Predicting the presence or magnitude of traits based on genome sequences is a major challenge in modern evolutionary research, and improving our understanding of the relationships between genotypes and phenotypes can help us to more accurately forecast how populations will respond to changing environmental conditions. Cases of convergent evolution, in which the same trait has evolved independently in different lineages, are particularly useful in addressing this challenge. We used comparative genomics to investigate the molecular basis of tetrodotoxin (TTX) resistance, which has evolved independently in multiple snake species that consume TTX-bearing amphibians. We found evidence for a predictable, stepwise pattern of nucleotide substitution occurring in the genes targeted by TTX (members of the voltage-gated sodium channel gene family). We also found evidence for positive selection within the TTX-binding regions of these genes. In addition to selective pressure, changes in genetic structure and increased mutation rates may have contributed to the evolution of resistance in select colubrid snake species. These results shed light on the molecular underpinnings of complex trait evolution, and provide a basis to search for similar patterns in other taxa that encounter TTX, such as the toxic amphibians themselves.

Microbiome mediated plant-pollinator interactions in non-agricultural systems

Authors: Ariel Heminger* 1 and David C. Haak 1

Affiliations: 1. School of Plant and Environmental Sciences, Virginia Tech

Plant-pollinator interactions are one of the most widely recognized coevolutionary relationships. Darwin attributed the rapid diversification of flowering plants to this close association with their insect partners and these partners often depend on plants for pollen and nectar as a food source. Woven into this relationship are microorganisms that form close relationships with their hosts forming the microbiome. The microbiome is intricately associated with the organismal health through processes such as nutrient acquisition and disease suppression. This suggests that flowers and their pollinators could have reciprocal influences on their associated microbes that have been shaped over evolutionary time. Few studies have examined the impact of this reciprocal interaction on microbial community structure, eco-evolutionary dynamics, or plant health. This study aims to fill this gap through characterizing the floral and pollinator microbiome across several natural populations of Solanum carolinense and Solanum dulcamara (an introduced species) and their pollinator Bombus spp. Eighty samples from the first year of the study were sequenced which resulted in 1475 unique OTUs before filtering. Preliminary results from these samples indicate that the floral microbiome changes throughout the developmental stage of the flower and that OTUs were differentially abundant on caged versus uncaged flowers. This suggests that pollinators introduce particular microbes to flowers during their visits, therein shifting the floral microbiome. Future studies aim to determine the similarities between the pollinator microbiome (gut and pollen baskets) and the flowers they visit. These studies will contribute to the body of knowledge on plant-pollinator interactions at the microbial level.

The influence of extra-pair activity on the cloacal microbiome of a free-living bird

Authors: Jessica Hernandez* 1, Lisa Belden 1, Ignacio Moore 1

Affiliations: 1. Department of Biological Sciences Virginia Tech

Socially monogamous females that engage in extra-pair activity (e.g., solicitations, copulations, fertilizations) face potential fitness trade-offs including, but not limited to, good genes and genetic diversity in offspring, but also loss of paternal care and increased harassment by their social partner. Sexually transmitted (pathogenic) microbes have been suggested to be a cost of extra-pair activity for female birds for nearly five decades, but this hypothesis has not yet been adequately tested. To determine how extra-pair activity is related to the composition of the cloacal microbiome, we performed an observational study on free-living female tree swallows (Tachycineta bicolor) during the breeding season in southwestern Virginia. Tree swallows are a socially monogamous, box-nesting species that exhibit high rates of extra-pair activity, with high variation both within and between populations, and thus are an appropriate system for this study. First, we characterized the cloacal microbiome of females by collecting cloacal swabs and determining the taxonomic composition of cloacal bacteria using 16s rRNA gene amplicon sequencing. Then, we used nestling paternity as a conservative proxy to estimate the frequency and success of extra-pair copulations, and to determine the minimum number of sexual partners per female. This study increases our understanding of how sexual activity, specifically extra-pair copulations, influences the presence, prevalence, and potential pathogenicity of cloacal microbial communities in wild birds. Additionally, this study broadens our understanding of the potential costs of different solutions to common life-history tradeoffs faced by free-living animals.

Implications of a changing climate on bird development

Authors: Hope, S.F.* 1, DuRant, S.E. 2, Kennamer, R.A. 3, Hopkins, W.A. 1

Affiliations: 1. Department of Fish and Wildlife Conservation, Virginia Tech 2. Department of Biological Sciences, University of Arkansas 3. Savannah River Ecology Lab, University of Georgia

Our changing climate may pose a threat to the early developmental environment of animals. The effect of climate change on developing reptiles is well-studied, and there is evidence that changes in incubation temperature can have substantial effects on offspring. In contrast, the effects of temperature changes on bird phenotypes have been historically overlooked because parents regulate incubation temperature. However, studies have shown that changes in the environment can affect avian parental incubation behavior, and that small changes in incubation temperature can affect avian offspring phenotypes. Yet, few studies have investigated how environmental changes may directly and indirectly influence incubation temperature, or how incubation temperature influences avian offspring behavior. We used wood ducks as a model system to address these questions. Our results show that wood duck nests with the largest clutch sizes and the lowest ambient temperatures led to the lowest incubation temperatures. We also found that ducklings incubated at 35.0 and 37.0 C exhibited bolder and more exploratory behaviors than those incubated at 35.8 C, while those incubated at 35.0 C were less successful at exiting the nest (a crucial behavior for wood duck ducklings) than those incubated at the other two temperatures. This research shows that environmental changes influence avian incubation temperature and thus, may influence offspring behaviors that are critical for survival. In this case, warming temperatures may be beneficial to developing birds, but future work should address how extreme weather events or changes in food availability due to climate change affect incubation temperature.

Female aggression in song sparrows is higher in urban habitats

Authors: Lane, S.J.* 1, Linkous, C.R. 1, Brewer, V. 2, Sewall, K.B. 1

Affiliations: 1. Virginia Polytechnic Institute and State University 2. New Mexico State University

Urban adapters are animals that are able to live in human-impacted areas, such as suburbs and cities. It has been hypothesized that urban adapters have behavioral phenotypes that permit them to persist in human-impacted environments. Indeed, song sparrows (Melospiza melodia) live and breed in both urban and rural habitats and previous research has shown that urban males of this species show greater territorial aggression. However, little attention has been given to female behavior across urban and rural habitats. To determine if living in urban habitats is associated with elevated aggression in female song sparrows, we simulated the intrusion of a conspecific female onto the social territory of females at two rural and two urban study sites in Blacksburg, VA. We placed a model bird 5 to 10 m of the focal bird’s nest and played one of 6 exemplars of recorded female vocalizations. For 3 minutes without the model and 6 minutes after model exposure, we measured the focal female’s distance from the speaker and the duration of vocalizations produced by the female as a measure of aggression. Female song sparrows nesting in urban habitats were more likely to respond to a simulated female intruder and showed a greater behavioral response to conspecific intrusions than did females in rural habitats. This pattern of greater female aggression in urban habitats parallels previous reports of greater territorial aggression in males and raises the hypothesis that resource competition may increase in urban environments, driving increased territorial aggression in both sexes of song sparrows.

Water quality at the point of use in San Rafael Las Flores, Guatemala

Authors: Marcillo, C.* 1, Garc Prado, G. 2, Copeland, N. 3, Krometis, L.A. 1

Affiliations: 1. Department of Biological Systems Engineering, Virginia Tech 2. Centro de Estudios Conservacionistas, Universidad de San Carlos de Guatemala 3. Department of Sociology, Virginia Tech

Limited information is available describing point of use water quality in rural Guatemala, particularly with respect to geologic contaminants, such as arsenic, associated with chronic health risk. This effort aimed to characterize drinking water in San Rafael Las Flores, a Guatemalan community directly adjacent to a large silver mine, to identify key contaminants of health concern. Surveys on water use and perception were conducted in 31 households, with water samples concurrently collected and analyzed for E. coli, pH, conductivity, and metals. Survey results indicated widespread distrust and dissatisfaction with in-home piped water. The majority (77%) of participants perceived their tap water to be unsafe and preferred drinking bottled water or from community springs. The majority (84%) also identified at least one aesthetic issue with their tap water (e.g. color, particulates) and only 25% of homes had continuous water service. Concerns predominantly revolved around potential health risks from arsenic and bacteria with widespread perceptions of contamination, most commonly attributed to the nearby mine. Though only two samples exceeded the 10 ppb arsenic standard, 45% were above 9 ppb. In addition, 13% of samples were positive for E. coli. Continued research is recommended to quantify potential arsenic biomarkers and critical exposure pathways. The establishment of a baseline water quality profile, confirmation of field test kit potential, and understanding local water quality concerns will permit the design of future interventions and citizen science efforts to engage the local community in discussions of potential infrastructure and land use development.

Ecological patterns and significance of secondary metabolites in a Neotropical shrub, Piper sancti-felicis

Authors: Maynard, L. D.* 1 and Whitehead, S. R. 1

Affiliations: 1. Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia, USA

Rooted in place, plants often rely on secondary metabolites to mediate interactions with other organisms. Both attraction of mutualists and defense against antagonists are thought to be mediated by secondary metabolites. Piper is one of the largest genera of flowering plants, containing about 1,000 species. This study describes the secondary metabolites occurring in the infructescences of Piper sancti-felicis and their functional significance in ecological interactions. We focused on one group of compounds: alkenylphenols. We had three specific objectives: 1) to elucidate the structures of the major alkenylphenol compounds present in P. sancti-felicis; 2) to describe the natural variation in alkenylphenol composition throughout reproductive tissue development and across individual plants; and 3) to test the ecological significance of the alkenylphenols in plant defense against fungi. Results suggest that alkenlyphenol concentration in infructescences significantly differed among individual plants, developmental stages, and individual compounds. Alkenylphenol concentration was higher in ripe and unripe infructescences compared to inflorescences with high interspecific variation. Results from the microdilution bioassays revealed that as alkenylphenol concentration increases, fungal absorbance decreases. This is the first study to describe alkenylphenols in P. sancti-felicis and their ecological function as defensive secondary metabolites, possessing anti-fungal properties.

Terminal electron acceptor processes in metalimnetic oxygen minima changes the annual methane budget in a eutrophic freshwater reservoir

Authors: McClure R.P.* 1, Lofton M. E. 1, Schreiber M.E. 2, Little J.C. 3, and Carey C.C. 1

Affiliations: 1. Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia, USA 2. Department of Geosciences, Virginia Tech, Blacksburg, Virginia, USA 3. Department of Civil and Environmental Engineering, Virginia Tech, Blacksburg, Virginia, USA

Freshwater reservoirs are heavily influenced by humans and commonly develop Metalimnetic Oxygen Minima (MOM) in their water columns because of different water management practices. MOM are also known to accumulate large quantities of methane (CH4) in them and change the seasonal CH4 efflux phenology. While the causes of MOM are known, less is known about their effects on CH4 production and the depletion of terminal electron acceptors (TEA) that precedes methanogenesis. MOM create distinct redox gradients in the water column that changes the distribution of CH4, but whether the CH4 is derived from methanogenesis in the MOM or from laterally entrained CH4 from methanogenesis occurring in the sediments remains unclear. We monitored profiles of CH4 and the TEAs that precede methanogenesis at five sites from the inflow to the dam in a eutrophic reservoir that develops a MOM as a result of the operation of water quality engineering systems. We observed large fluctuations in the TEA availability in the MOM and little fluctuation in TEAs at other depths in the water column that remained oxygenated. We also observed lateral entrainment of CH4 from upstream depths that coincided with the MOM. This suggests that the CH4 that is observed in MOM is from TEA depletion followed by methanogenesis in both upstream sediments and in MOM that have become anoxic. This poses new uncertainties to annual CH4 budgets in freshwater reservoirs if TEA processes that normally occur in the sediments are also occurring directly in the water column.

Do good neighbors make up for poor conditions? Case study on a mixed-flocking habitat specialist

Authors: McNeill, N.* 1 and Walters, J. 1

Affiliations: 1. Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia, USA

Birds are known to form foraging flocks in numerous systems, many of which are mixed-species flocks. Individuals may choose to a mixed-flock in order to increase foraging efficiency, limit intraspecific competition, or reduce predation. In the longleaf pine system of the southeastern United States, brown-headed nuthatch (Sitta pusilla) mixed-flock during the nonbreeding season, but are subject to variable predator presence and food availability throughout this period. Furthermore, it is unknown whether this species forgoes the boundaries of its small breeding territories in order to follow mixed-species flocks. Thus, I am recording mixed-flocking behavior of brown-headed nuthatch at Marine Corps Base Camp Lejeune. Nuthatch behavior and mixed-flock interactions will be recorded. Individual nuthatches will be color banded in order to locate breeding territories and track individual movement. Additionally, I will experimentally manipulate food availability by placing feeding stations in portions of the field site. I will then record station recruitment rates and flocking behavior surrounding these stations. I expect that tendency to forage in mixed flocks is inversely correlated to food availability and individual territory quality. As food becomes scarce in winter, flock foraging reduces the predator vigilance required by each individual, increasing foraging efficiency. Determining how these factors impact nuthatch behavior will inform habitat management strategies for improved winter survival.

Resource Use and Interspecific Interactions in a Namibian Cavity-nesting Community

Authors: David Millican* 1, Jeff Walters 1, and Ashley Dayer 2

Affiliations: 1. Department of Biological Sciences, Virginia Tech 2. Department of Fish and Wildlife Conservation, Virginia Tech

Cavity-nesting guilds are diverse communities of animals found in forest ecosystems worldwide. Due to their dependence on tree holes for nesting, populations of these species are highly susceptible to forms of disturbance that diminish cavity availability. Namibia is the driest country in sub-Saharan Africa, with a landscape largely depauperate of large trees, the most common harborers of cavities. This community is threatened by numerous anthropogenic disturbances, including charcoal production, altered grazing and fire regimes, and increasingly frequent and severe droughts caused by climate change. To aid the conservation of this threatened community, we have embarked on a multi-year nest-web analysis to quantify community structure. Through this analysis, we seek to describe the type of nest cavities available in the landscape, species-specific resource use preferences, and direct and indirect interactions between community members. Quantifying community structure willprovide important information for land use managers who want to mitigate impacts of anthropogenic disturbance on this community. To aid conservation of this community, we have alsoembarked on a sociological study to identify a potential flagship species. By using emotional prompts to identify wildlife perceptions of local communities, we hope to identify a potential flagship species that will effectively bring awareness to the plights facing this community, and to encourage behavior change in the form of preserving large, cavity-bearing trees. By combining ecological and sociological research, we hope to generate recommendations for both ecological management as well as sociological strategies to generate local support for a conservation campaign.

Male Red-cockaded Woodpecker dispersal habitat analysis

Authors: Leah D. Novak* 1, Jeffrey R. Walters 1, and Dylan Kesler 2

Affiliations: 1. Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia, USA 2. The Institute for Bird Populations, Point Reyes Station, CA

Natal dispersal is the movement of individuals from a birth site to a breeding site. Juveniles often foray before dispersal, that is explore outside their natal territory to gather information from the environment and conspecifics regarding habitats and conditions. Individuals choose specific habitat characteristics to travel through and explore while foraying. Understanding what habitat characteristics an individual uses while foraying is key for identifying important resources which promote exploration and movement during dispersal, and for creating and implementing effective management strategies especially for endangered species, such as the Red-cockaded Woodpecker (RCW). The cooperatively breeding RCW is a federally listed endangered species endemic to open, southern pine savannah in the Atlantic and Gulf Coastal Plains of the United States. Juvenile male RCWs have two dispersal syndromes: they can either delay dispersal and remain on their natal territory as non-breeding helpers or disperse their first year in search of territories with open breeder positions. Dominance within broods plays an important role in determining which dispersal strategy a juvenile male will use. Dominant males almost always remain as helpers, while subordinate males disperse their first year. Despite understanding dispersal outcomes of male and female RCWs, very little is known about the dispersal process and behavior of males. Therefore, I followed dominant and subordinate juvenile, and adult helper males using radio-telemetry, and recorded GPS coordinates and behavioral observations to determine dispersal behavior and habitat use. Overall, juvenile and helper males tended to use habitats that had high quality foraging resources (older, larger longleaf and loblolly pines) and were hidden from other RCW families‚ a group of cavity trees (called a cluster), though male RCWs did seek out other RCW clusters if the family group that guarded that cluster was not present.

Predicting golden-crowned sifaka (Propithecus tattersalli) density from habitat and nutritional variables

Authors: Semel, B.P.* 1, Karpanty, S.M. 1, Semel, M.A. 2, Walters, G.T. 1, Ranaivoson, T.N. 3, and Rothman, J.M. 4

Affiliations: 1. Dept. of Fish and Wildlife Conservation, Virginia Tech  2. Dept. of Biological Sciences, Virginia Tech  3. Dept. of Zoology and Animal Biodiversity, University of Antananarivo  4. Dept. of Anthropology, Hunter College of CUNY, NY

Understanding relationships between animal populations and nutritional variables is important for effectively managing threatened animal populations in dynamic environments. Madagascar’s lemurs are threatened by forest destruction, yet we know very little about how populations will respond to the additional threat posed by climate change. In northeastern Madagascar, critically endangered golden-crowned sifakas (Propithecus tattersalli) live in dry, deciduous to humid rain-forests across a unique biogeographic transition zone. This makes them an ideal case study in which to examine the effects of climate-mediated forest type variables and plant nutrition on sifaka population densities. Specifically, we will investigate the relationships between tree species densities, canopy cover, species diversity, normalized difference vegetation index (NDVI), available plant fiber, energy, and protein values on sifaka densities in ten different forest fragments. Results will help us to better understand how forest type and nutritional variables impact lemur populations. This will help conservation managers to protect key forest habitats and to select the most important tree species for ongoing reforestation efforts. Future work will employ climate models to predict future forest cover types and ultimately, future sifaka population abundance across the species’ range.

Impact of habitat type and disturbance level on golden-crowned sifaka (Propithecus tattersalli) social cohesion and ranging behavior

Authors: Meredith Semel* 1, Julie Ratovoson 2, Ignacio Moore 1

Affiliations: 1. Department of Biological Sciences, Virginia Tech 2. Biology and Conservation, University of Antananarivo

Madagascar, an island off the coast of southeast Africa, is one of the world’s richest biodiversity hotspots, yet little is known about how habitat degradation will affect imperiled species. Golden-crowned sifakas (Propithecus tattersalli), listed as critically endangered on the IUCN red list, are folivorous, group living primates endemic to forests of northern Madagascar. Golden-crowned sifakas display a flexible behavioral strategy called fission-fusion, which results in individuals periodically separating from group members (fissions) and rejoining after temporal and spatial separation (fusions). We are seeking to examine how fragmentation and landscape heterogeneity influence fission-fusion dynamics, ranging behavior, and overall social cohesion in this species. To do this, we completed 7 full-day behavioral follows for nine groups of golden-crowned sifakas in an array of rainforest and dry forest fragments surrounding Daraina, Madagascar (August-December 2018). Using scans at ten-minute intervals, we recorded activity, height, feeding information, nearest neighbor proximity, and group spread. Overall, we found that fragment type resulted in a significant amount of variance on group spread and territory size; with sifakas displaying decreased group cohesion in rainforest fragments, possibly due to decreased food availability and separating from group members to acquire necessary nutrients. Now that we have an understanding of P. tattersalli behavior we will be employing the use of novel tracking devices to automate our data collection and more effectively collect group cohesion and ranging data.

Scientists’ roles in policy-making

Authors: Seo, H.* 1

Affiliations: 1. School of Public and International Affairs, Virginia Tech

This paper explores scientists’ roles in policy-making based on literature review with the aim of gaining insights into how policy processes might be enhanced through better science-policy interactions. Integrating scientific knowledge into policy-making and management processes is challenging because of the inherently different purposes, assumptions, and framing of scientific information and policy information (Innes & Booher, 2010). When it comes to research about environmental issues such as biodiversity and conservation, it is even more difficult to use scientific research to inform policy-making and implementation because these environmental issues are particularly complex in nature, involving uncertainty, complexity, diverse conflicting values and multiple objectives in various sectors; science alone cannot provide simple, optimal solutions (Young et al., 2014). To address these challenges, this paper starts with two paradigms of science-policy interactions which determine scientists’ roles required in society: the democratic and technocratic approaches. Further, it examines theories about boundary work at science-policy interfaces, and reviews existing typologies of scientists roles. It concludes with a discussion of future direction for research.

Do Roots Bind Soil? Comparing the Physical and Biological Role of Roots in Fluvial Streambank Erosion Resistance

Authors: Smith, D.J.* 1 and Thompson, T.M. 1 

Affiliations: 1. Department of Biological Systems Engineering , Virginia Tech

Today, it is recognized that plant roots affect streambank erosion through various processes, including: 1) physical binding of soil particles by roots, 2) gluing soil particles together due to the release of extracellular polymeric substances (EPS) by soil microorganisms, and 3) alterations to the streambank fluvial boundary layer. However, the relative importance of these mechanisms is not fully understood. To quantify the effects of roots and soil microbial communities on erosion resistance, laboratory testing was conducted using a jet erosion test device‚ an erosion measurement tool used measure soil erodibility and critical shear stress. Erosion resistance measurements were also correlated with plant, soil, and microbial parameters, including EPS, aboveground biomass, root length density (RLD), and aggregate stability. The experimental setup included five treatments: 1) sterile soil, 2) sterile soil with synthetic roots, 3) inoculated soil, 4) inoculated soil with synthetic roots, and 5) inoculated soil with live roots. Critical shear stress was significantly increased in Treatments 2, 4, and 5 compared to Treatment 3 by 67%, 75%, and 79%, respectively. As RLD and aggregate stability increased in vegetated samples (Treatment 5), soil critical shear stress significantly increased as well. However, soil erodibility was also significantly increased by 33% in Treatment 4 compared to Treatment 1. In addition, Treatment 5 saw a significant 10% decrease in aggregate stability in samples compared to all other treatments. These results suggest that the physical presence of fibers or the biological activity of microorganisms alone may not significantly impact soil resistance to fluvial erosion.

The Screech Owl Nest Web: A New Opportunity for Citizen Science in Montgomery County, Virginia

Authors: Ben Vernasco* 1 and Ignacio Moore 1 

Affiliations: 1. Department of Biological Sciences, Virginia Tech

Citizen science projects rely upon the public to assist in the scientific process and these projects are known to have a number of benefits. Citizen science 1) promotes engagements between the public and scientists, 2) increases scientific literacy and 3) expands data collection opportunities to a level beyond what is possible by a single researcher. Birds that nest in artificial nest boxes present a unique opportunity for citizens to engage in the scientific process by providing a nesting cavity on their property and monitoring the nesting progress of the inhabitants. Here, I propose to establish a new citizen science project for Montgomery County that entails establishing and monitoring nest boxes specifically designed for Eastern Screech Owls (Megascops asio). Eastern Screech Owls are currently declining in parts of their range, including Virginia, and a lack of nesting cavities is a contributing factor. The owls are known to occupy artificial nest boxes in the suburban and rural habitats present in Montgomery County. With this program, we can monitor the nesting success of this charismatic bird. Additionally, the proposed project can also address questions related to breeding phenology, population demography, dispersal behaviors, and the effects of urbanization on wildlife. Beyond the local level, participants can submit their data to the NestWatch Program established by the Cornell Lab of Ornithology. Overall, the proposed project can contribute to the conservation of a declining species, establish a new study system for the GCC community, and, most importantly, engage the public in the scientific process.

Estimating Occupational Heat Exposure from Personal Sampling of Public Works Employees in Birmingham, Alabama

Authors: Suwei Wang* 1,5, Molly B. Richardson 1, Connor Y.H. Wu 2, Carly D. Cholera 3, Claudiu T. Lungu 3, Benjamin F. Zaitchik 4, Julia M. Gohlke 1

Affiliations: 1. Department of Population Health Sciences, Virginia Tech, Blacksburg, VA 2. Department of Geospatial Informatics, Troy University, Troy, AL 3. School of Public Health, University of Alabama at Birmingham, Birmingham, AL 4. Department of Earth & Planetary Sciences, Johns Hopkins University, Baltimore, MD 5. Translational Biology, Medicine, and Health, Virginia Tech, Blacksburg, VA

Excessive occupational heat stress has been associated with increased mortality and injury rates. Wet bulb globe temperature (WBGT) index is widely used to assess heat stress and recommend work-rest cycles combined with metabolic rates of workers. Currently, estimates of WBGT use meteorological data from nearby weather stations (WS), but likely do not reflect actual environmental conditions at a specific workplace. This study evaluated whether using thermometers clipped on workers shoes would result in different work-rest schedules compared to using area-level meteorological data alone.

Spatial variability in oligotrophic lake metabolism may indicate trophic state change due to localized stream loading

Authors: Nicole K. Ward* 1, Jennifer A. Brentrup 2, David C. Richardson 3, Kathleen C. Weathers 4, Cayelan C. Carey 1

Affiliations: 1. Department of Biological Sciences, Virginia Tech, Blacksburg, VA, USA 2. Department of Biological Sciences, Dartmouth College, Hanover, NH, USA 3. Biology Department, SUNY New Paltz, New Paltz, NY, USA 4. Cary Institute of Ecosystem Studies, Millbrook, NY, USA

Local land-use and global climate change are rapidly degrading oligotrophic lakes. Robust water quality indicators are needed to determine whether oligotrophic lakes are maintaining their low-nutrient state. Lake metabolism, the balance of carbon production and respiration, is an integrated ecosystem metric that may indicate impending ecosystem shifts to a meso- or eutrophic state. Ecosystem metabolism modeled from one deep site within a lake is often assumed to be representative of the entire lake; little is known about the relationship between lake metabolism estimates at near-shore sites and nutrient loading from the nearest inflow. Here, we ask: How do summer lake metabolism estimates at near-shore sites (4-7 m deep) compare to a single deep-site (13 m deep) estimate? We addressed this question in oligotrophic Lake Sunapee, New Hampshire (USA). We used high-frequency measurements of dissolved oxygen, water temperature, and light to estimate metabolism at three near-shore sites and one deep-site. We also measured stream discharge and nutrient concentrations in the closest inflow streams to each near-shore lake site to estimate localized nutrient loading. Net ecosystem metabolism at Lake Sunapee’s deep-site was consistently positive (range = 0.01‚ 0.5 mg-O2/L/day) whereas all three near-shore sites averaged near zero net ecosystem metabolism (range = -0.4 – 0.3 mg-O2/L/day). Localized stream nutrient loading was positively correlated with daily maximum GPP and R rates. Linking spatially variable lake metabolism to heterogeneous nutrient loading provides insight into how lakes integrate catchment land use, providing an indicator of impending shifts in lake trophic state.

How can the cavity nest-web inform conservation of the endangered Bahama Swallow (Tachycineta cyaneoviridis)?

Authors: Maya Wilson* 1 and Jeffrey R. Walters 1

Affiliations: 1. Department of Biological Sciences, Virginia Tech

The Bahama Swallow (Tachycineta cyaneoviridis) only breeds in the northern Bahamas, and is considered endangered due to decline in its population. However, causes of population decline are unknown. As an obligate secondary cavity nester, the swallow requires other species or processes to create cavities in which to nest. We constructed a cavity nest-web to investigate whether nest site availability and interactions between swallows and other cavity-nesting species could provide insight into causes of decline and the design of conservation strategies. We conducted surveys to assess the availability of cavity-nesting resources in Caribbean Pine (Pinus caribaea) forest and other habitats. We also examined potential competition by locating nests of all other cavity-nesting species. We measured reproductive success by monitoring swallow nests in different cavity types. Swallows built nests in several cavity types, primarily those excavated by Hairy Woodpeckers (Picoides villosus) and West Indian Woodpeckers (Melanerpes superciliaris). La Sagra’s Flycatchers (Myiarchus sagrae) were the only other secondary cavity nesters that utilized the sparsely distributed pine snag cavities, which are excavated by Hairy Woodpeckers. Other cavity types were in anthropogenic structures and were concentrated in developed areas, where swallows face potential competition with American Kestrels (Falco sparverius), and non-native House Sparrows (Passer domesticus) and European Starlings (Sturnus vulgaris). Reproductive success was high during all nest stages in pine snags, while success in other cavity types appeared to vary. These findings indicate that managing for pine snags and the presence of Hairy Woodpeckers in the pine forest may be crucial to Bahama Swallow conservation.

Convergent evolution and high cranial disparity in the close relatives of archosaurs as demonstrated in Doswellia sixmilensis (Archosauriformes: Proterochampsia)

Authors: Wynd, B. M.* 1, Nesbitt, S. J. 1, Stocker, M. R. 1, Heckert, A. B. 2

Affiliations: 1. Department of Geosciences, Virginia Tech 2. Department of Geological and Environmental Sciences, Appalachian State University

The Triassic Period (252 – 200 Ma) records a great expansion of reptile diversity and disparity, particularly in skull morphology. Close relatives of archosaurs (group including birds and crocodiles) exhibit substantial range in cranial disparity, especially by species shortening or elongating the skull. This disparity is exemplified in North American Late Triassic proterochampsians by short-faced and long-faced doswelliids. To investigate skull elongation and character evolution in proterochampsians, we evaluate the taxon, Doswellia sixmilensis, from the Late Triassic of New Mexico. We redescribe D. sixmilensis based on repreparation of the skull material and reinterpret what was previously regarded as the antorbital fenestra to be the orbit. Because of this, the identification of bones and the taxon diagnosis must be substantially modified. We score D. sixmilensis into a phylogeny of archosaurs and their close relatives, consisting of 676 characters and 109 taxa. We recover Doswelliidae as a monophyletic clade nested within the South American Proterochampsidae. This challenges previous interpretations of the Doswelliidae and suggests previously unrecognized cranial disparity within Proterochampsidae. To reconstruct archosauromorph cranial disparity, we place D. sixmilensis and other proterochampsians into a similarity analysis of 36 taxa and 42 cranial characters using a non-metric multidimensional scaling ordination plot. We find that early diverging proterochampsians explore regions of morphospace explored only by long-snouted taxa (archosaurs and their close relatives), and are disparate from other skull forms. This indicates that archosaur relatives experimented with the anterior half of their skulls with a combination of unique and convergent characters present in the earliest archosaurs.

Detailed AGENDA PDF

Thursday, April 19, 2018

9:15 a.m.         Poster setup; Fralin Hall Atrium

9:55 a.m.         Welcome (Jeff); Fralin Auditorium

10:00 a.m.       Session 1 (S1); Session Chair: Angie Estrada

10:00 a.m.       S1 Talk 1 Ben Vernasco

10:15 a.m.       S1 Talk 2 Ryan McClure

10:30 a.m.       S1 Talk 3 Fadoua El Moustaid

10:45 a.m.       S1 Talk 4 Carl Wepking

11:00 a.m.       Break and poster viewing

11:30 a.m.       Session 2 (S2); Session Chair: Jon Doubek

11:30 a.m.       S2 Talk 1 Maya Wilson

11:45 a.m.       S2 Talk 2 Zach Gajewski

12:00 p.m.       S2 Talk 3 Brenen Wynd

12:15 p.m.       S2 Talk 4 Tamara Fetters

12:30 p.m.       Lunch and poster viewing; Fralin Atrium

1:30 p.m.         Session 3 (S3); Session Chair: Derek Hennen

1:30 p.m.         S3 Talk 1 Mike Graham

1:45 p.m.         S2 Talk 2 Bennett Grooms

2:00 p.m.         S2 Talk 3 Gifty Anane-Taabeah

2:15 p.m.         S2 Talk 4 Ernie Osburn

2:30 p.m.         S2 Talk 5 Zach Martin

2:45 p.m.         Poster Reception (students by posters)

3:45 p.m.         Platform Award Announcements

4:00 p.m.         Symposium Adjourns

All IGC fellows are encouraged to present their work at the symposium. Fellows have the option of presenting either a poster or a talk. Awards will be given for best talks.

Abstracts for talks and posters should be submitted to Jessica Zielske (jcoker@vt.edu). Each abstract should contain:

1. Title
2. Authors and Affiliations (e.g., Department and University)
3. An abstract not to exceed 250 words in length

For posters: maximum poster size is 40″ x 60″.  An easel and backboard will be provided.

The influence of social behavior and stability on disease transmission in a songbird host 

Authors: Matt Aberle 1, Jim Adelman 1, Dana Hawley 1

Affiliations: 1. Biological Sciences, Virginia Tech 

Human wildlife provisioning has long been overlooked as a major ecological factor, but in the last ten years it has been shown to be an important factor on the social behavior and physiology of wildlife and, consequently, disease. A prime example is among house finches (Haemorhous mexicanus) who, since the mid-1990s, have been subject to infection with a highly contagious bacterium, Mycoplasma gallisepticum, which causes debilitating conjunctival pathology. House finches congregate at bird feeders in social flocks, where most transmission takes place, making it an ideal system for testing hypotheses regarding how human provisioning influences social behavior, physiology, and disease transmission. To test the impact of bird feeders, I altered feeder density across several sites on the Virginia Tech campus while using radio-frequency identification to track social networks and individual behavior. By altering the density of feeders, my results show the effects of human feeding via bird feeders on this disease system by seeing changes in the social networks of house finches, individual behavior and physiology, and the prevalence of disease. 

Assessing local adaptation and physiological plasticity of a montane lizard in a warming climate

Authors: Brooke L. Bodensteiner 1 and Eric J. Gangloff 2

Affiliations: 1. Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 2. Station d’Ecologie Théorique et Expérimentale du CNRS Moulis, France

Determining how organisms will be impacted by a warming world is one of the most pressing scientific imperatives of the 21stcentury. Habitat tracking – species’ range shifts to more suitable habitat – is perhaps the most commonly observed response to rising temperatures. Terrestrial species are clearly moving upward in elevation and poleward in latitude. Nonetheless, there is a key asymmetry in habitat tracking, with species’ shifts to higher elevations occurring much more slowly than shifts to higher latitude. The mechanism for this asymmetry, however, remains predominantly unexplored. We do know that that species-specific physiological thresholds, relating to climate, set species’ distributions. For example, tracking suitable temperatures at higher elevations comes with the additional physiological challenge of contending with progressively limited oxygen concentrations. The goal of this project is to empirically test how oxygen availability across elevation may be limiting upslope migrations in a widespread terrestrial vertebrate the Common Wall Lizard (Podarcis muralis). I hypothesize that local temperature regimes and oxygen availability will interact to shape physiological traits, and the plasticity of these traits, in lizard populations from differ thermal regimes and levels of oxygen availability. By elucidating these interwoven factors, we can gain a more holistic understanding of the constraints organisms will encounter as they are faced with environmental warming.

Ailanthus Biocontrol

Authors: Rachel K Brooks 1, Scott Salom 2, Anton Baudoin 1

Affiliations: 1. Department of Plant Pathology, Physiology, and Weed Science, Virginia Polytechnic and State University, Blacksburg, VA  2. Department of Entomology, Virginia Polytechnic and State University, Blacksburg, VA

Ailanthus altissima (tree-of-heaven) is an invasive Chinese tree that has taken over portions of the Virginia landscape. Current control tactics are limited to expensive chemical and mechanical methods, and are impractical over large areas. Recently, two species of Verticillium fungi have been found naturally killing Ailanthus in Virginia. A statewide field inoculation study is underway to determine (1) if either of these isolates can be used as an effective biological control agent in the state, and (2) if any climate or stand variables impact Verticillium’s effectiveness. Preliminary results from the first field season indicate that V. nonalfalfae, alone or in combination with V. dahliae, cause significantly higher disease ratings than just V. dahliae or a control treatment. Additionally, disease progression was significantly influenced by two stand and climate variables: maximum temperature and tree height.

Examining the role of dispersal pathways in structuring aquatic insect communities

Authors: Sara Cathey 1 and Bryan L. Brown 1

Affiliations: 1. Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia

Aquatic insects use different pathways to disperse between communities. This heterogeneity in dispersal behavior may affect how communities of stream macroinvertebrates are structured and how variable insect assemblages are over time. For my dissertation, I will investigate what role different dispersal pathways play in the assembly of aquatic macroinvertebrate communities in a stream network and how this dispersal-driven assembly changes with position in the network. I will also investigate how this dispersal-driven community assembly affects the stability of stream macroinvertebrate communities, taking into account both the taxonomic and trait composition of stream macroinvertebrate communities. I predict that isolated headwater communities are structured more by aerial dispersal, while mainstem communities located at nodes in the network are structured more by drift dispersal. The influence of drift dispersal from the headwaters that structures mainstem communities will diminish with an increase in the stream order of the mainstem. I predict community stability will be lowest in headwater assemblages and highest in the mainstem sites. These studies will help elucidate how different dispersal routes structure communities and stabilize communities. Determining how dispersal drives community assembly may give us insight into how these communities respond to disturbance, habitat fragmentation, and biological invasion. Understanding the assembly of aquatic insect communities may also inform conservation and restoration strategies.

Base cations as drivers of bacterial water quality impairment

Authors: Stephen DeVilbiss 1, Meredith Steele 1, Brian Badgley 1

Affiliations: 1. Department of Crop and Soil Environmental Sciences, Virginia Tech, Blacksburg, VA

Base cations (Ca, Mg, K, Na) are common constituents of both terrestrial and aquatic environments. However, human activities including agriculture, deicing, surface mining, and construction have resulted in increasing ion concentrations in North American surface waters. While it is well established that the total inorganic ion concentration, or salinity, significantly impacts aquatic bacteria, the effects of individual base cations on bacterial ecology are unknown. Further, most studies focus on broad salinity ranges from freshwater to marine, and fail to address small scale changes in ion concentrations. As freshwaters continue to become saltier from manageable anthropogenic activity, small increases in salts (<50 mg/L or 350 μS/cm), as well as the types of salts causing those increases, may become increasingly important drivers of ecosystem health.We have previously identified strong correlations between base cations and the fecal indicator bacterium E. coliin watersheds in Southwestern Virginia. However, mechanisms driving these correlations in the environment have yet to be experimentally tested and remain a substantive knowledge gap. Here, we test the effect of elevated concentrations of individual base cations on the survivability of E. coliin controlled mesocosm experiments. Results suggest that divalent base cations, Ca and Mg, significantly increase the survivability of E.colirelative to K treatments and controls with no salt additions. These results suggest that elevated concentrations of divalent base cations may increase bacterial impairments in surface waters.

Does the microbiome impact reintroduction success of captive species? A test with an endangered frog

Authors: Angie Estrada 1, Daniel Medina 1, Brian Gratwicke 2, Roberto Ibanez 3, Lisa K. Belden 1

Affiliations: 1. Department of Biological Sciences, Virginia Tech  2. Smithsonian’s National Zoo & Conservation Biology Institute  3. Smithsonian Tropical Research Institute, Panama.

Beneficial skin bacteria can protect amphibians against Batrachochytrium dendrobatidis(Bd), a deadly pathogenic fungus that is one of the largest threats to amphibian survival worldwide. For many amphibian species, long-term captive breeding programs have prevented extinction; however, captive management is known to modify the amphibian skin microbiome. In Panamá, threatened amphibian species survive in captive breeding facilities, but have only recently been experimentally reintroduced into the wild. For tropical amphibians, it is unknown how skin bacterial community diversity and structure change once captive-bred individuals are re-exposed to natural habitats. Thus, to inform the development of beneficial bacteria-based treatments, and also future reintroduction efforts, we attempted to understand amphibian-Bd-skin bacterial community interactions in reintroduced captive-bred individuals. Specifically, we assessed the changes that occur in the bacterial communities of Atelopus limosus, a critically-endangered species, following reintroduction to a site where the species historically occurred. We aimed to investigate how the initial skin bacterial community influences: 1) bacterial community structure and composition after release, 2) host condition and 3)Bdinfection status. Relative abundance of bacterial OTUs (operational taxonomic units, ~bacterial species) based on 16S rRNA gene amplicon sequencing was used to assess skin bacterial community diversity. We found significant variation in bacterial community structure before and after release.  In addition, we found variation in bacterial community structure through time once exposure to natural conditions occurred. Moreover, after only two weeks, reintroduced and wild individuals had more similar skin microbiomes. These preliminary findings suggest that skin-associated microbiomes can be restored once captive-bred individuals are re-exposed to natural habitats, but future research needs to address whether these changes in bacterial structure ultimately result in higher survival and Bd protection of captive-bred amphibians.

Connecting long-term data with fine-scale variation: using remote sensing to evaluate spatiotemporal dynamics of drylands ponds

Authors: Mary Jade Farruggia 1, Meghan Halabisky 2, Meryl C. Mims 1

Affiliations: 1. Virginia Tech – Department of Biological Sciences  2. University of Washington and Conservation Science Partners

Hydroperiod is a major driver of aquatic communities in lentic systems and may be particularly relevant in areas where water availability is a major limiting factor. In the American Southwest, water availability is threatened by unsustainable water use and increased drought. There, manmade lentic habitats such as cattle ponds may provide critical habitat for aquatic organisms when natural systems are lost. However, spatial distribution and hydroperiod dynamics of manmade ponds in this region are poorly understood, representing a knowledge gap about spatiotemporal availability of lentic habitat. To address this, we asked: (1) How are manmade ponds spatially distributed in this region? (2) Which ponds are permanent, and which are intermittent? (3) What are the ponds’ hydroperiods, and do they change over time? We will use graph theory and spectral mixture analysis to analyze 34 consecutive years (1983-2017) of satellite imagery in Coronado National Forest, Arizona, to characterize the spatial distribution of ponds on the landscape, estimate surface water, and classify hydroperiods across multiple time scales. As global change progresses, understanding regional water availability is increasingly important for contextualizing aquatic community stability and optimizing management to promote persistence of native aquatic organisms.

Evidence of an adaptive trade-off in a weedy, invasive grass grown near the edge of its distribution

Authors: Rebecca A. Fletcher 1, Daniel Z. Atwater 1,2, David C. Haak 1, Jacob N. Barney 1

Affiliations: 1. Department of Plant Pathology, Physiology and Weed Science, Virginia Polytechnic Institute and State University, Blacksburg, Virginia  2. Department of Biology, Earlham College, Richmond, Indiana

The rapid range expansion of some exotic invasive plants is thought to be facilitated by their ability to quickly adapt to the novel environmental conditions they experience in their new ranges. However, fitness trade-offs may constrain adaptation, especially at the geographic range periphery where genetic diversity may be low, thereby, restricting further range expansion. One important fitness trade-off is that of earlier flowering time. Flowering earlier has been found in plant populations growing near the periphery of their distributions. Life history theory predicts that plants that flower early will be smaller in size, which results in decreased reproductive output. We used the globally distributed, invasive plant Johnsongrass (Sorghum halepense) to determine whether populations originating from the range periphery (where Johnsongrass is rare) exhibit characteristics consistent with the adaptive trade-off between flowering time and reproductive output. We collected populations of Johnsongrass from the center, edge, and periphery of its distribution and grew them in a common garden experiment located near Blacksburg, VA. We found the periphery populations were half the size of the other populations and flowered 10 days earlier, but we did not find evidence of reduced reproductive output in the periphery populations. This suggests that there is a trade-off between flowering time and investment in growth, but this trade-off did not seem to affect the reproductive output of Johnsongrass. Further studies are needed to determine why Johnsongrass has not successfully colonized regions beyond the edge of its distribution.

Evolutionary mechanisms of toxin resistance in snakes and lizards

Authors: Kerry L. Gendreau 1, Angela D. Hornsby 1, Joel W. McGlothlin 1

Affiliations: 1. Biological Sciences, Virginia Tech, Blacksburg, VA

Parallelism describes convergent evolution using a shared mechanism and can occur at multiple scales (i.e. at the molecular, phenotypic, and/or ecological levels). Convergent evolution of toxin resistance in snake species is a well-characterized example of molecular parallelism. Tetrodotoxin (TTX), used as a chemical defense by some fish and amphibian species, causes paralysis by targeting vertebrate sodium channel proteins necessary for the propagation of action potentials in muscles. Nine types of sodium channel proteins are present in vertebrates, each with different kinetic properties and levels of tissue expression. Substitutions in a functionally conserved region of the sodium channel gene expressed in skeletal muscle (SCN4A) provide some snakes with resistance to high levels of TTX, and have evolved convergently in distantly related species that consume toxic amphibian prey. Resistance to TTX in SCN4A appears to have evolved over a relatively short timespan in snakes experiencing strong selective pressure from consuming toxic amphibians. In contrast, sodium channels expressed in heart muscle and sensory neurons acquired resistance before the split of the last common ancestor of snakes and lizards, and may be necessary to drive selection on skeletal muscle channels. Using the genome sequences of species representing major phylogenetic branches of the order Squamata(snakes and lizards) as well as the tuatara,we will gain insight into the evolutionary history of the entire voltage gated sodium channel gene family. This will shed light on the amount and scale of parallelism in this gene family and the mechanisms controlling convergent evolution under conflicting selective pressure.

Microbiome mediated plant-pollinator interactions

Authors: Ariel Heminger 1, David C. Haak 1,

Affiliations: 1. Department of Plant Pathology, Physiology, and Weed Science, Virginia Polytechnic and State University, Blacksburg, VA

Plants and their pollinators depend heavily on the synergy of one another. The majority of flowering plants require pollinators to ensure the spread of pollenand pollinators often depend on plants for pollen and nectar as a food source. In agriculture alone native pollinators contribute between $4.1 to $6.7 billion dollars annually. Woven into this relationship are microorganisms that form close relationships with their hosts forming the microbiome. The microbiome is intricately associated with the organismal health through processes such as nutrient acquisition and disease suppression. Recent studies have found that pollinators exchange microbes with the flowers they pollinate—leaving a microbial fingerprint. This suggests that flowers and their pollinators could have reciprocal influences on their associated microbes that have been shaped over evolutionary time.  However, few studies have examined the impact of this reciprocal interaction on microbial community structure, eco-evolutionary dynamics, or plant health. This study aims to fill this gap through three specific objectives:  1) characterizing the floral and pollinator microbiome across several natural populations of Solanum carolinenseand its pollinator Bombus spp., 2) examining the same traits in populations (paired with 1) of a congener Solanum dulcamarathat was introduced less than 200 years ago, and 3) investigating the impact of the pollen microbiome on seed endophytic communities.By focusing on the microbial interactions between a native plant species Solanum carolinense, horsenettle, and an introduced species Solanum dulcamara, bittersweet nightshade and their pollinators, Bombus spp. in Virginia. This study will contribute to the body of knowledge on plant-pollinator interactions at the microbial level and help further determine how the microbiome is linked to plant and pollinator health.

Chemical defense gland evolution in a millipede Müllerian mimicry ring

Authors: Derek A. Hennen 1, Paul. E Marek 1

Affiliations: 1 Department of Entomology, Virginia Polytechnic Institute & State University, Blacksburg, VA

Apheloriine millipedes are common detritivores found in the undergrowth of Appalachian temperate forests. They exhibit an array of bold color patterns, which function as aposematic signals advertising their unpalatability to potential predators such as birds. The toxicity of these millipedes is due to their paired, bi-compartmental chemical defense glands, which produce a poisonous mix of hydrogen cyanide and benzaldehyde at levels sufficient to kill 18 pigeon-sized birds. Shared chemical defenses and color patterns have been noted in the group before, and a Müllerian mimicry ring among seven species in three different genera (Apheloria, Appalachioria, and Brachoria) has recently been documented in the Cumberland Mountain Thrust Block Region of Virginia, Tennessee, and Kentucky. In this mimicry ring, Apheloria was hypothesized to be the more toxic model, with Appalachioria and Brachoria mimicking Apheloria color patterns. However, the hypothesis of Apheloria as the model in this mimicry ring has not been directly tested. To investigate this question, we compared the size of the chemical defense glands in sympatric populations of the genera Apheloria and Brachoria as a proxy for toxicity. We found that the chemical defense glands of Apheloria were significantly larger than those in Brachoria, supporting the hypothesis that Apheloria acts as the more toxic model in the mimicry ring.

Sexually transmitted pathogenic bacteria as a cost of extra-pair activity to female birds

Authors: Jessica Hernandez 1,

Affiliations: 1. Department of Biological Sciences, Virginia Polytechnic Institute & State University, Blacksburg, VA

Important questions in evolutionary and organismal biology often center around the trade-offs of different mating strategies. Up until the 1980s, most bird species were considered to be truly monogamous, or sexually faithful to a social partner. However, with recent molecular advances, the evidence suggests quite the opposite pattern: nearly 90% of bird species engage in fertile copulations outside of the social pair (i.e., extra-pair fertilizations). Sexually transmitted diseases have been suggested to be a cost of extra-pair fertilizations in birds for the past four decades, but has not yet been adequately tested.This research focuses on a local population of box-nesting tree swallows (Tachycineta bicolor), a species in which individuals have been shown to be socially monogamous, yet also engage in high rates of extra-pair fertilizations. We collected cloacal samples from adult male and female tree swallows during the 2016 breeding season, and subsequently extracted, amplified, and sequenced the bacterial DNA from those cloacal samples. Here, we present preliminary data that we used to answer the question: What is the relationship between the cloacal bacterial communities of males and females, in general, and of social pairs? With regard to cloacal bacterial communities, we found that 1) there is variation within sexes and 2) social pairs were not more similar compared to other sampled individuals in the same population. Our next step is to assess the relationship between cloacal bacterial communities and rates of extra-pair fertilizations. Ultimately, we hope to shed some light on the relationship between extra-pair fertilizations and the presence, prevalence, and potential pathogenicity of sexually transmitted microbes, with respect to fitness, in a wild avian population.

Implications of a changing climate on bird development

Authors: Sydney F. Hope 1, Sarah E. DuRant 2, Robert A. Kennamer 3, William A. Hopkins 1

Affiliations: 1. Department of Fish and Wildlife Conservation, Virginia Tech 2. Department of Integrative Biology, Oklahoma State University 3. Savannah River Ecology Lab, University of Georgia

Our changing climate may pose a threat to the early developmental environment of animals. The effect of climate change on developing reptiles is well-studied, and there is evidence that changes in incubation temperature can have substantial effects on offspring. In contrast, the effects of temperature changes on bird phenotypes have been historically overlooked because parents regulate incubation temperature. However, studies have shown that changes in the environment can affect avian parental incubation behavior, and that small changes in incubation temperature can affect avian offspring phenotypes. Yet, few studies have investigated how environmental changes may directly and indirectly influence incubation temperature, and no studies have investigated how incubation temperature influences avian offspring behavior. We used wood ducks as a model system to address these questions. Our results show that wood duck nests with the largest clutch sizes and the lowest ambient temperatures led to the lowest incubation temperatures. We also found that ducklings incubated at 35 and 37°C exhibited bolder and more exploratory behaviors than those incubated at 35.8°C, while those incubated at 35°C were less successful at exiting the nest (a crucial behavior for wood duck ducklings) than those incubated at the other two temperatures. This research shows that environmental changes influence avian incubation temperature and thus, may influence offspring behaviors that are critical for survival. In this case, warming temperatures may be beneficial to developing birds, but future work should address how extreme weather events or changes in food availability due to climate change affect incubation temperature.

Mapping Climate Envelopes to Hypothesize Ecotypic Variation of an Invasive Plant

Authors: Vasily Lakoba 1 and Jacob Barney 1

Affiliations: 1. Department of Plant Pathology, Physiology, and Weed Science, Virginia Polytechnic Institute and State University, Blacksburg, Virginia

Invasive plants cause an estimated 35 billion dollars in damage and control costs in the United States annually (Pimentel et al., 2005). Johnsongrass (Sorghum halepensePers., Poaceae) is a global invasive species with a prominent range in the southern half of the continental United States. Over its 190-year invasion history in the U.S., it has shown a directional transition from agricultural to non-agricultural habitats (Sezen et al., 2016). Recently, agricultural and non-agricultural lineages were found to respond divergently to climate variables (Atwater et al., 2016). By studying human land uses as drivers of ecotypic divergence, we can begin to predict invader spread and physiology in the landscape with greater sensitivity.

In this project, U.S. Johnsongrass observations 1981-2018 from the Global Biodiversity Information Facility (GBIF) and the Early Detection and Distribution Mapping System (EDDMapS) were used to sample PRISM climate norm data for 1981-2010. The observations were then subset based on human land uses and the resulting climate envelopes were projected on the continental United States. This method found divergent climate envelopes based on temporal, (non)agricultural, land-use-change, and impervious surface subsetting. It also found three distinct cores within the range, which had previously been considered as largely an east-west dichotomy.

Geospatial evidence supports the connection between human land uses and Johnsongrass climate responses. These GIS analyses are a rationale for locating range cores with the highest likelihood of ecotypic variation for in-situ measurement of soil and plant community predictors of divergent adaptation.

Urbanization impacts nestling corticosterone but not offspring growth in song sparrows

Authors: Lane, S. 1, Sewall, K. 1

Affiliations: 1. Department of Biological Sciences, Virginia Tech, Blacksburg VA

Urbanization represents a dramatic and relatively rapid change in environment, which animals may cope with through phenotypic plasticity. In previous studies, it has been shown that male song sparrows (Melospiza melodia) in urban habitats show higher levels of territorial aggression than their rural counterparts. Such differences in male behavior could have consequences for offspring, as territorial aggression can be traded off against paternal care. Therefore, we compared nestling growth, corticosterone (CORT) levels, and survival among three rural populations (N = 15 nests/30 nestlings) and two urban populations (N=19 nests/45 nestlings) of song sparrows near Blacksburg, VA. We found that nest predation was higher in rural habitats, based on evidence of disturbance at the nest site. Additionally, we found that nestling baseline CORT levels were significantly higher in rural habitats, though there were no differences in overall nestling growth rates. Finally, there was a non-significant trend towards increased nest parasitism by brown-headed cowbirds in urban habitats. These findings suggest that male territorial aggression does have consequences for offspring CORT levels. Additionally, these findings suggest that there are differences in relative risks of predation and nest parasitism across rural and urban habitats, which could potentially drive variation in male territorial aggression.

Whole-ecosystem experiments reveal differential responses of phytoplankton functional groups to epilimnetic mixing

Authors: Mary Lofton 1, Ryan McClure 1, Shengyang Chen 2, John Little 3, Cayelan Carey 1

Affiliations: 1. Biological Sciences, Virginia Tech 2. Civil Engineering, University of Sydney 3. Civil & Environmental Engineering, Virginia Tech

Phytoplankton blooms are increasing in lakes and reservoirs worldwide, causing detrimental effects on drinking water quality. One management strategy for controlling phytoplankton is epilimnetic mixing systems, intended to decrease surface scums by increasing water column turbulence. However, past work has demonstrated that the efficacy of epilimnetic mixing for decreasing phytoplankton biomass is equivocal. This may be because phytoplankton community responses to epilimnetic mixing are mediated by mixing effects on other ecosystem processes, such as nutrient dynamics and thermal stratification, and quick-sinking phytoplankton taxa may benefit from a well-mixed water column. To assess effects of epilimnetic mixing at the whole-ecosystem scale, we conducted two mixing experiments in a drinking water reservoir. We measured a suite of physical, chemical, and biological variables before, during, and after mixing and compared the results to a nearby, unmixed reference reservoir. We found that phytoplankton biomass, especially cyanobacteria, green algae, and cryptophytes, significantly increased after our first mixing event due to an increase of nutrients, likely from entrainment of sediments into the epilimnion. Total phytoplankton biomass did not significantly change after our second mixing event; however, phytoplankton community composition after the second mixing event exhibited a shift from taxa with filamentous morphology to smaller, rounder taxa. Our results suggest that phytoplankton responses to epilimnetic mixing are intertwined with turbidity and nutrient dynamics, and that these responses may vary depending on the timing of mixing and morphology of phytoplankton taxa. Whole-ecosystem dynamics and functional traits should be considered when managing phytoplankton biomass by epilimnetic mixing.

Disparate drinking water quality and compliance across urban and rural Virginia under the Safe Drinking Water Act

Authors: Cristina E. Marcillo 1 and Leigh-Anne Krometis 1

Affiliations: 1. Department of Biological Systems Engineering, Virginia Polytechnic Institute and State University, Blacksburg, Virginia

Approximately 299 million Americans receive household drinking water from one of 51,350 community water systems (CWSs) under the Safe Drinking Water Act (SDWA). Despite a history of amendments and financial investment, repeated violations and noncompliance persists. This study hypothesizes that community exposures to drinking water contaminants are significantly different between rural and urban US communities. The goal was to analyze historic SDWA violations in Virginia to 1) understand the relationships between system size, rurality, and compliance and 2) evaluate the most prevalent drinking water contaminants.

Violation data from 1999-2016 for 1,135 Virginia CWSs were analyzed (n>9500 violations, source: Safe Drinking Water Information System). Systems were geocoded in ArcGIS, with the US Department of Agriculture’s Rural-Urban Commuting Area (RUCA) codes defining rurality at the zip code level. As would be expected, small systems serving less than 3,300 people each had 64% of all health-based violations across the state while very large systems serving more than 100,000 people each had 0.07% of all health-based violations. Analyses of geocoded CWSs (n=671) indicated that rurality had a significant effect on total (Kruskal-Wallis, χ2=22.39, p<0.01) and monitoring and reporting violations (χ2= 28.03, p<0.001). Additionally, both health based and monitoring and reporting violations were significantly different between differently sized systems.

Confirmation that SDWA compliance differs by rurality suggests that rural communities may be more likely to be exposed to drinking water contaminants of health concern. Ongoing efforts will expand this analysis to include the influence of community demographics (e.g. race, % foreign born) on SDWA compliance.

Why do birds of different feathers flock together? A case study on a cooperatively breeding habitat specialist

Authors: Noah McNeill 1, Dr. Jeff Walters 1

Affiliations: 1. Department of Biological Sciences, Virginia Tech University, Blacksburg, Virginia, USA

Birds are known to form flocks in numerous systems, many of which are mixed-species flocks. Individuals may choose to mixed-flock in order to increase foraging efficiency, limit intraspecific competition, or reduce predation. In the longleaf pine system, brown-headed nuthatch (Sitta pusilla) join mixed flocks during the nonbreeding season, but are subject to variable predator presence and food availability. I plan to record mixed-flocking rates of brown-headed nuthatch, as well as predator interactions at Marine Corps Base Camp Lejeune. Nuthatches will be color banded and surveyed using a combination of scan and focal sampling. Additionally, I will experimentally manipulate food availability by placing feeding stations in portions of the field site. I will then record station usage rates and flocking behavior surrounding these stations. I expect that tendency to join mixed flocks is inversely correlated to pine seed availability and individual territory quality. Alternatively, I expect mixed flocking to positively correlate with predator presence, particularly during the winter influx of migrant predators. Determining how these factors impact nonbreeding nuthatch behavior will inform population management strategies for improved winter survival.

Diversity and symbiosis: Examining the taxonomic, genetic, and functional diversity of amphibian skin microbiota

Authors: Myra Hughey 1, Matthew Becker 1, Tiffany Bridges 2, Brian Gratwicke 3, Reid Harris 2, Leanna House 4, Roberto Ibanez 3, Roderick Jensen 1, Stephen Loftus 4, Daniel Medina 1, Kevin Minbiole 5, Eria Rebollar 2, Thomas Umile 5, Jenifer Walke 1, Lisa Belden 1

Affiliations: 1. Department of Biological Sciences, Virginia Tech  2. Biology Department, James Madison University  3. Smithsonian Institution & Panama Amphibian Rescue and Conservation Project  4. Department of Statistics, Virginia Tech  5. Chemistry Department, Villanova University

For decades ecologists have contemplated the potential consequences of biodiversity loss, which has resulted in a rich literature searching for links between biodiversity and ecosystem function. Within this context, our research has aimed to understand the link between diversity and function by investigating the amphibian skin bacterial communities and their role in controlling the disease chytridiomycosis, caused by the fungus Batrachochytrium dendrobatidis(Bd).  Chytridiomycosis is decimating many amphibian populations in the Neotropics. Thus, our work has focused on investigating the link between bacterial community structure and function in Panamanian amphibians. We conducted a field survey to examined six host species that vary in Bd susceptibility at a Bd naïve site, and a second survey to examine three non-susceptible host species across sites that varied in timing of Bd arrival. Bacterial community structure was assessed using 16S rRNA gene amplicon sequencing, and their potential function was assessed by using HPLC-MS to produce profiles of secondary metabolites. In addition, we also assessed inhibition of Bd growth by bacterial isolates cultured from these skin communities. Overall, we found host species-specific skin bacterial communities, and that these communities may vary among populations of the same species across sites. In addition, host species that are more susceptible to Bd differed in their skin bacterial communities from more resistant species. Moreover, the arrival of Bd at a site may result in shifts in bacterial community structure. However, metabolite profiles across species were not always distinct, suggesting that similar functions might result from different bacterial community structures.

Resource Use and Interspecific Interactions in a Namibian Cavity-nesting Community

Authors: David Millican 1, Jeff Walters 1, Ashley Dayer 2

Affiliations: 1. Department of Biological Sciences, Virginia Tech, 2. Department of Fish and Wildlife Conservation, Virginia Tech

Cavity-nesting guilds are diverse communities of vertebrates and invertebrates found in forest ecosystems worldwide. Due to their dependence on tree holes for nesting, species in these communities are limited by an availability of suitable nest cavities. This dependence therefore leaves these species susceptible to forms of disturbance that diminish cavity availability, such as anthropogenic forest management, stochastic events, and climatic shifts. Namibia is the driest country in sub-Saharan Africa, with a landscape largely depauperate of large trees, the most common harborers of cavities. This community is threatened by numerous anthropogenic disturbances, including charcoal production, altered grazing and fire regimes, and increasingly frequent and severe droughts caused by climate change. To aid the conservation of this threatened community, we have embarked on a multi-year nest-web analysis to quantify community structure. Through this analysis, we will seek to describe the type and structure of available nest cavities, species-specific resource use preferences, and direct and indirect interactions between community members. By quantifying community structure, we willprovide important information for land use managers to mitigate the impacts of anthropogenic disturbance on this community. We have also coupled our ecological research with a human dimensions study on wildlife perceptions of local communities. Using focus-group interviews, we are using emotional prompts as a way to identify a potential flagship species. By combining ecological and sociological research, we hope to generate both ecological management plans for conserving this community as well as sociological strategies to generate local support for a conservation campaign.

Time budgets of juvenile male Red-cockaded Woodpeckers before dispersal

Authors: Leah D. Novak 1, Jeffrey R. Walters 1, Dylan Kesler 2

Affiliations: 1. Biological Sciences, Virginia Tech 2. The Institute for Bird Populations

Natal dispersal is the movement of individual animals from a birth site to a breeding site.  Often, before dispersal, juveniles explore outside their natal territory to gather information from the environment and conspecifics regarding habitats and conditions.  Understanding the behavior of these individuals while they explore is key for understanding and predicting how a species interprets and interacts with the biotic and abiotic landscape, and is especially important for creating and implementing effective management strategies especially for endangered species, such as the Red-cockaded Woodpecker (RCW).  The cooperatively breeding RCW is a federally listed endangered species endemic to open, southern pine savannah in the Atlantic and Gulf Coastal Plains of the United States.  Male RCWs have two dispersal syndromes: they can either delay dispersal and remain on their natal territory as non-breeding helpers, or disperse their first year in search of territories with open breeder positions.  Dominance within broods plays an important role in determining which dispersal strategy a juvenile male will use.  Dominant males almost always remain as helpers, while subordinates disperse their first year.  Despite understanding dispersal outcomes of male and female RCWs, very little is known about the males behave during dispersal.  Therefore, I followed dominant and subordinate juvenile males using radio-telemetry and made behavioral observations to determine the time budgets of these individuals.  I found that subordinate and dominant juvenile males both forayed extensively. Juveniles spent most of their time foraging while foraying, especially in the morning, although dominant males tended to spend more time traveling than subordinate males.  Also, subordinate juveniles spent time exploring cavities in other RCW territories, which dominant males did not.

Representing forest management in Earth System Models

Authors: Joshua M. Rady 1, R. Quinn Thomas 1

Affiliations: 1. Department of Forest Resources and Environmental Conservation, Virginia Polytechnic Institute and State University

As the major terrestrial carbon sink forests are seen as a critical tool to help combat climate change.  A quarter of the emissions reductions pledged in the Paris Climate Accords come from preservation and expansion of forests.  Given the stakes it is critically important that we make wise choices in employing these mitigation approaches.  In this context forest management techniques developed to increase timber production might be usefully repurposed to increase carbon sequestration.  Forests both influence and are influenced by climate.  Therefore, fully coupled Earth System Models (ESMs) must be used to fully understand the effects of the mitigation approaches that employ forests.  Currently ESMs simulate forest management in a rudimentary manner.  Some important management activities, like harvest rotation and fertilization, are not represented at all.  We have completed the initial steps to incorporate these management activities into the Community Land Model, the terrestrial component of NCAR’s CESM Earth System Model.  We have altered the hierarchical representation of vegetation on the model’s gridded land surface.  This allows us to isolate portions of forest in a grid cell for management activities.  In initial experiments, we have demonstrated the isolation of wood harvest onto a specified segment of forest, where previously it occurred everywhere.  This lays the groundwork for increasingly relevant activities such as fertilization, fire exclusion, harvest rotations, as well as representing protected forest areas.  We hope these improvements will increase the value of these models to decision makers in the climate policy arena.

Population trends in northern Madagascar’s endangered and critically endangered lemurs: Should we be concerned?

Authors: Brandon P. Semel 1, Sarah M. Karpanty 1, François Angelo Andrianiaina 2, Katherine A. Lipford 1, Dimbison Vévé Rasolomanana 3

Affiliations: 1. Department of Fish & Wildlife Conservation, Virginia Tech, Blacksburg VA  2. Department of Animal Conservation & Biology, University of Antananarivo, Madagascar  3. Department of Life Sciences & the Environment, University of Mahajanga, Madagascar

Habitat loss, hunting, and climate change continue to threaten Madagascar’s lemurs. Despite the rapid creation of protected areas during the first part of the century, we still know precious little about lemur populations across the island. Three diurnal lemur species can be found across less than 440 km2of fragmented forests within the Loky-Manambato Protected Area. Critically endangered golden-crowned sifakas (Propithecus tattersalli) are endemic to the region and have been the focus of several studies across the protected area. Little is known about endangered crowned (Eulemur coronatus) and Sanford’s brown (E. sanfordi) lemurs in the region. Standard line transects were used to survey these and other vertebrate species in a total of nine fragments from 2016-2017. Species densities and abundance were determined using the “Distance” package in Program R. Population estimates suggest a decline in sifaka populations since 2006/2008. However, local taboos seem to continue to protect this species form hunting. Here, we present the first estimates of crowned and Sanford’s brown lemurs in the region. Evidence of continued forest loss, disturbance, and hunting of the two Eulemur species was found across all survey areas, even those that were conducted in strict conservation zones (noyaux durs). We suggest that increased patrols of conservation areas be conducted to prevent continued biodiversity loss in the protected area.

Material based upon work supported by the NSF GRFP (No. DGE 1607310). Opinions, findings, conclusions, or recommendations expressed are thoseof the authors and do not necessarily reflect the views of the NSF.

Exploring group cohesion and social proximity in golden-crowned sifakas

Authors: Meredith Semel 1, Yasmireilda Richards 2, Nicole Abaid 3, and Ignacio Moore 1

Affiliations: 1. Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia  2. Department of Animal Biology and Conservation, University of Antananarivo, Madagascar 3. Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, Virginia

Traditionally, studies examining group cohesion in primates have taken a “boots and binoculars” approach. While observational data is effective in understanding primate social behavior, it is challenging and the data are limited by the amount of time the investigator can spend monitoring the troop. Commercially available tracking equipment is promising but their application limited due to high cost. To address this issue, we have designed a modular, open-source tracking collar, FitPET (“FITness, Proximity, Energetics, and Tracking”), that is capable of collecting data on primate cohesionandcan provide truly innovative insights into how habitat structure and fragmentation influence group cohesion. To determine how primate social cohesion is impacted by landscape type and to ground-proof the use of our devices, we completed 7 full-day behavioral follows for eleven groups of golden-crowned sifakas (Propithecus tattersalli) in an array of rainforest and dry forest fragments surrounding Daraina, Madagascar (August-December 2017). Using scans at ten-minute intervals, we recorded activity, height, feeding information, nearest neighbor proximity, and group spread. Group spread was determined by measuring the distance between the farthest two individuals in each group. Overall, we observed a relationship between fragment type and group spread; with sifakas displaying decreased group cohesion in rainforest fragments. Now that we have an understanding of how P. tattersallisocial cohesion differs between fragment types, we willbe employing the use of our FitPET devices to automate our data collection and more effectively collect data on spatial dynamics and social interactions of sifaka groups.

Land use versus climate drivers of algal production in an oligotrophic lake: it depends on season

Authors: Nicole K. Ward 1, Bethel Steele 2, Kathleen C. Weathers 2, Kathryn L. Nottingham 3, Holly A. Ewing 4, Paul C. Hanson 5, Robert Wood 6, June Fitcher 6, Cayelan C. Carey 1

Affiliations: 1. Biological Sciences, Virginia Tech  2. Cary Institute of Ecosystem Studies 3. Biological Sciences, Dartmouth College  4. Program in Environmental Studies, Bates College  5. Center for Limnology, University of Wisconsin-Madison  6. Lake Sunapee Protective Association

Globally, lake water quality is decreasing as a result of global warming and excess nutrient loading from land use change (e.g. clearing of forests). Clear-water, or oligotrophic, lakes are particularly vulnerable to changes in water quality; they can “flip” to a low-water quality state through the essentially irreversible process of eutrophication. To work toward maintaining oligotrophic lakes and the highly valuable ecosystem services they provide (e.g. drinking water and recreation), managers and scientists need to understand the relative contribution of land use and climate drivers to water quality change. Here, we address the question, how is land use and climate affecting water quality in an oligotrophic lake over 3 decades? Our study site is Lake Sunapee, which is the 3rdlargest lake in New Hampshire. The lake experiences variable annual phosphorus loading, precipitation, and air temperature. Average annual air temperature is increasing at a rate of 0.04 °C per year (from 1979 to 2016;r2= 0.36). We calibrated and validated a 1-dimensional hydrodynamic model coupled with an aquatic ecosystem model to simulate lake dynamics over 3 decades. In analyzing each summer growing season, multiple linear regression analysis shows that summer (Jun-Jul-Aug) chlorophyll-a, a measure of algal production, is driven primarily by summer temperature (contributing to 91% of overall model fit), whereas fall (Sept) chlorophyll-a is driven primarily by spring (Mar-Apr-May) phosphorus loading (contributing to 83% of overall model fit). Unique drivers to algal production at different times of year have important implications for managing valuable oligotrophic lake ecosystems in the face of global warming and land use change.

Environmental dissemination of antibiotic resistance in dairy manure and compost-amended vegetable fields

Authors: Wind, L. 1, Hession W.C. 1, Krometis L.-A. 1, Chen C. 2, Du P. 3, Pruden A. 4

Affiliations: 1. Virginia Tech, Biological Systems Engineering, Blacksburg, United States  2. Virginia Tech, Crop and Soil Environmental Sciences, Blacksburg, United States  3. Virginia Tech, Statistics, Blacksburg, United States  4. Virginia Tech, Civil and Environmental Engineering, Blacksburg, United States

Increasing evidence links the widespread use of antibiotics in livestock production to the transfer of bacteria carrying antibiotic resistance genes (ARGs) to the broader environment. It is therefore critical to understand the persistence and mobility of both resistant microorganisms and associated genetic material in these systems in order to understand potential threats to consumers. We evaluated the effects of soil amendment type (inorganic fertilizer, raw dairy manure, composted dairy manure, or no amendment), vegetable type (lettuce, radish), and antibiotic use (pirlimycin and cephapirin) of cattle manure-derived amendments on the incidence of culturable antibiotic-resistant fecal coliforms through a field-scale controlled plot experiment. Antibiotic-resistant culturable fecal coliforms were recoverable from soils across all treatments immediately following application, though persistence throughout the experiment varied by antibiotic class and time. Compost-amended soils had the highest levels of cephalosporin-resistant fecal coliforms, regardless of the antibiotic history of the cows providing the manure. Significantly, higher levels of total, ceftazidime, and erythromycin-resistant fecal coliforms were recovered from compost-amended as compared to the raw manure-amended soils. Parallel quantification of resistance genes (sul1, tet(W), erm(B), intI1) was used to confirm observed culturable trends. Soils amended with raw dairy manure yielded high relative sul1 and tet(W) gene copies on Day 0, correlating with an observed spike in associated ARBs, and remained detectable for 113 and 39 days longer than resistant bacteria, respectively. Interestingly, erm(B) was not detected, despite detection of erythromycin-resistant bacteria in the soil and erm(B) in a parallel runoff study. This work is of particular interest given the relevance of fecal coliforms in tracking human pathogen risk in multiple environments (e.g., water, crops) throughout agricultural production.

Detailed AGENDA PDF

Friday, April 21, 2017

8:30 a.m.         Poster setup; Fralin Hall Atrium

9:10 a.m.         Welcome (Jeff); Fralin Auditorium

9:15 a.m.         Session 1 (S1); Session Chair: Heather Govenor

9:15 a.m.         S1 Talk 1 Laura Schoenle

9:30 a.m.         S1 Talk 2 Tamara Fetters

9:45 a.m.         S1 Talk 3 Brandon Semel

10:00 a.m.       S1 Talk 4 Derek Hennen

10:15 a.m.       Premiere: Freshwaters in the Anthropocene (Science Communication Films; Cayelan Carey)

10:55 a.m.       Break

11:15 a.m.       Keynote Talk (Bob Inglis)

12:15 p.m.       Lunch and poster viewing; Fralin Atrium

1:15 p.m.         Session 2 (S2); Session Chair: Derek Hennen

1:15 p.m.         S2 Talk 1 Max Ragozzino

1:30 p.m.         S2 Talk 2 Tony Timpano

1:45 p.m.         S2 Talk 3 Heather Govenor

2:00 p.m.         S2 Talk 4 Mary Lofton

2:15 p.m.         S2 Talk 5 Zach Martin

2:30 p.m.         Poster Reception (students by posters)

3:30 p.m.         Platform Award Announcements

3:45 p.m.         Symposium Adjourns

All IGC fellows are encouraged to present their work at the symposium. Fellows have the option of presenting either a poster or a talk. Please indicate your preference by Friday, March 3rd. Awards will be given for best talks.

Abstracts for talks and posters should be submitted to Gloria Schoenholtz (schoeng@vt.edu) by March 31, 2017.  Each abstract should contain:

1. Title
2. Authors and Affiliations (e.g., Department and University)
3. An abstract not to exceed 250 words in length

For posters: maximum poster size is 40″ x 60″.  An easel and backboard will be provided.

The influence of social behavior and stability on disease transmission in a songbird host

Authors: Matt Aberle 1, James Adelman 2, Sahnzi Moyers 1, Dana Hawley 1

Affiliations: 1. Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia; 2. Department of Natural Resources and Ecology Management, Iowa State University, Ames, Iowa.

Human wildlife provisioning has long been overlooked as a major ecological factor, but in the last ten years it has been shown to be an important factor on the social behavior and physiology of wildlife and, consequently, disease. A prime example is among house finches (Haemorhous mexicanus) who, since the mid-1990s, have been subject to infection with a highly contagious bacterium, Mycoplasma gallisepticum, which causes debilitating conjunctival pathology. House finches congregate at bird feeders in social flocks, where most transmission takes place, making it an ideal system for testing hypotheses regarding how human provisioning influences social behavior, physiology, and disease transmission. To test the impact of bird feeders, I altered feeder density across several sites on the Virginia Tech campus while using radio-frequency identification to track social networks and individual behavior. By altering the density of feeders, my results should be able to show the effects of human feeding via bird feeders on this disease system by seeing changes in the social networks of house finches, individual behavior and physiology, and the prevalence of disease.

Loblolly pine and switchgrass: A year of eddy flux measurements in Virginia

Authors: Benjamin J. Ahlswede 1, R. Quinn Thomas 1, Tom O’Halloran 2

Affiliations: 1. Department of Forest Resources and Environmental Conservation, Virginia Polytechnic Institute and State University; 2. Forestry and Environmental Conservation Department, Clemson University

How do land-use transitions affect climate? Land-use is a large component of human emissions of CO2 to the atmosphere. But these transitions have immediate, local, biophysical impacts on surface climate as well. As climate change continues the market for biophysical effects and other climate services will continue to grow. What land-types provide the greatest climate services in the southeastern United States?

We have been gathering data from the eddy flux covariance systems at Sweet Briar College in central Virginia for the past year. These two towers measure fluxes of water, carbon and energy as well as relevant meteorological measurements over a switchgrass field and a loblolly pine stand respectively. These measurements allow us to make assessments of the exchange of carbon and the biophysical effects on climate.

After a year of data, the switchgrass field shows the most biophysical benefit. This is mostly due to its high albedo. In addition, the switchgrass has a higher rate of carbon absorption than loblolly pine during peak growth. However, this must be contrasted with the large amount of CO2 emitted by the grass system during non-peak growth, ultimately making it a net source of carbon. The Pine system continues to be a carbon sink all year, but what fluxes may emerge after a harvest event remains unknown.

Identifying local strains of Nile tilapia Oreochromis niloticus that are adapted to future climate conditions

Authors: Gifty Anane-Taabeah 1,2, Emmanuel Frimpong 1, Stephen Amisah 2, Akwasi Ampofo-Yeboah 3, and Eric Hallerman 1

Affiliations: 1. Department of Fisheries and Wildlife Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia; 2. Department of Fisheries and Watershed Management, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana, 3. Department of Fisheries and Aquatic Resources Management, University of Development Studies, Nyankpala Campus, Ghana

This study was conducted to synthesize information on the ambient water quality (temperature, dissolve oxygen and salinity) for the Nile tilapia, an important commercial species, compare wild populations in the Volta basin and the selectively bred Akosombo strain from the basin used in fish farming in Ghana under current and future climate conditions, and develop predictive models delineating the boundaries of the species’ range. A combination of literature survey, field and laboratory methods provided data for meta-analysis, growth and genetic analysis, as well as distribution models. We found variations in water temperature along the latitudinal gradient in Ghana; and temperature was the most informative variable in terms of characterizing the adaptive range and ambient water quality for the species. The results of the growth studies showed no evidence of superior performance of the Akosombo strain over the wild strains under current or predicted future climatic conditions of temperature, dissolved oxygen, or salinity. Significant Fst values from the genetic analysis suggested that the Akosombo strain was well differentiated from all the wild populations (Aframso, Sabare and Binaba) studied. The combined results of the field, growth and genetic studies show that at least one wild population from the Oti River (Sabare) may possess the traits for superior performance under high temperature and low DO conditions. Further studies should concentrate on comparing the Sabare strain with the Akosombo strain under different experimental conditions and increase replications to confirm the suggested differences and the heritability of those performance traits for selective breeding.

Tree-of-Heaven (Ailanthus altissima) biocontrol

Authors: Rachel Brooks 1, Scott Salom 2, Anton Baudoin 1

Affiliations: 1. Department of Plant Pathology, Physiology, and Weed Science, Virginia Polytechnic Institute and State University, Blacksburg, Virginia; 2. Department of Entomology, Virginia Polytechnic Institute and State University, Blacksburg, Virginia

Abstract: Ailanthus altissima, commonly known as the tree-of-heaven, has been successfully invading the North American landscape since its introduction from China over 200 years ago. Today, it is found in over 40 states along transportation corridors, on agricultural fields, within urban areas, and in forest stands displacing native species. Long-term and wide-spread control using chemical and mechanical methods have been ineffective in containing this tree. Recently, two strains of naturally occurring fungi (Verticillium nonalfalfae and V. dahliae) have caused entire Ailanthus stands in Ohio, Pennsylvania, and Virginia to decline and die, effectively removing the invasive species from the area. Preliminary work from Pennsylvania shows that V. nonalfalfae has the potential to become a cheap, effective, and safe biocontrol agent. This summer, we will determine if these two fungal pathogens also have the potential to become effective control agents in Virginia. Ailanthus stands throughout Virginia have been identified and mapped, and conidia suspensions of one or both species will be injected into the trees in May. Disease progression and spread will be monitored monthly and analyzed to compare differences between hardiness zones. Has our environment given us an effective tool to fight this aggressive invader?

Hypoxia-induced trade-offs on zooplankton vertical distribution and community structure in reservoirs

Authors: Jonathan P. Doubek 1, Kylie L. Campbell 1, Kaitlyn M. Doubek 1, Kathleen D. Hamre 1, Charlotte W. Harrell 1, Mary E. Lofton 1, Ryan P. McClure 1, Nicole K. Ward 1, and Cayelan C. Carey 1

Affiliations: 1. Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia

Because of global change, lakes and reservoirs worldwide are increasingly experiencing low dissolved oxygen concentrations (hypoxia). Although the effects of hypoxia on internal nutrient loading have been well-studied, less is known about how hypoxia impacts plankton communities, especially zooplankton. Typically, zooplankton migrate to the dark bottom waters (hypolimnion) during the day to escape visual fish predation in the well-lit surface waters (epilimnion). However, due to the physiologically-stressful conditions of hypoxic hypolimnia, zooplankton may remain in the epilimnion during daylight, trading oxic stress for increased predation risk. We sampled five reservoirs weekly to biweekly during the daytime in southwestern Virginia, USA over three summers to examine how hypolimnetic oxygen concentrations impact the vertical distribution, density, biomass, and community composition of macrozooplankton and rotifers. These reservoirs varied on a gradient of hypolimnetic oxygen concentrations, from no oxygen to high oxygen during the sampling period. In addition, we also conducted ten 24-h sampling campaigns on reservoirs across this same oxygen gradient to examine how zooplankton were vertically distributed over day-night periods. Under hypoxic conditions, zooplankton were predominately found in the epilimnion during the day and night, did not exhibit diel vertical migration, and had overall lower densities and biomass than in reservoirs that exhibited oxic hypolimnia. Only two zooplankton taxa were found predominately in hypoxic zones. Zooplankton play a critical role in lakes and reservoirs as the dominant grazers of phytoplankton, and our results suggest that hypolimnetic hypoxia may alter zooplankton vertical distribution and densities, which may in turn exacerbate water quality degradation.

Mathematical modeling of cyanobacterial dynamics in a chemostat 

Authors: Fadoua El Moustaid 1, Ross P. Carlson 2, Federica Villa 3, Isaac Klapper 4

Affiliations: 1. Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia; 2. Center for Biofilm Engineering, Montana State University, Bozeman, MT; 3. Department of Food, Environmental and Nutritional Sciences, Università degli Studi di Milano, Milano, Italy; 4. Department of Mathematics, Temple University, Philadelphia

We present a mathematical model that describes how cyanobacterial communities use natural light as a source of energy and water as a source of electrons to perform photosynthesis and therefore, grow and co-survive together with other bacterial species. The purpose of our model is to explain interactions between bacteria. In particular, we apply our model to a phototrophic population of bacteria, namely, cyanobacteria. Our model involves the use of light as a source of energy and inorganic carbon as a source of nutrients. First, we study a single species model involving only cyanobacteria, then we include heterotrophs in the two species model. A stability analysis is done and the obtained results show that adding heterotrophs increase the level of inorganic carbon in the medium which allows cyanobacteria, on one hand, to perform more photosynthesis, therefore increase their growth and on the other hand delay the excess of light damage which also benefits cyanobacterial growth.

Temporal variation of the skin microbiome in lowland amphibians and its implications for conservation

Authors: Angie Estrada 1, Myra C. Hughey, Eria A. Rebollar, Matthew H. Becker, Jenifer B. Walke, Daniel Medina 1, Roberto Ibáñez, Reid N. Harris and Lisa K. Belden 1

Affiliations: 1. Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia

The amphibian skin microbiome has been the focus of recent studies aiming to better understand its role in host defense against disease. However, host-associated microbial communities can be dynamic, and changes in their composition can influence their function. Understanding temporal variation of bacterial communities on amphibian skin is critical for establishing baselines from which to improve the development of mitigation techniques based on probiotic therapy and provide long-term host protection in a changing environment. Here, we investigated whether microbial communities on amphibian skin change over time across seasons and years at a single pond. To examine this, we collected skin swabs from two pond-breeding species of treefrogs (Agalychnis callidryas and Dendropsophus ebraccatus) for four years in a single lowland tropical pond in Panama. Relative abundance of OTUs based on 16S rRNA gene amplicon sequencing was used to quantify bacterial community diversity on the skin. We found variation between the two species within the same pond. In addition, we found significant variation in bacterial community structure across years for both species. We also found significant changes across seasons, but this was stronger in D. ebraccatus. Lowland amphibians species persist despite the presence of a fungal skin pathogen, Batrachochytrium dendrobatidis, which has caused declines in highland populations. These preliminary findings suggest that skin-associated microbiomes vary across time, but more research is necessary to elucidate the significance of temporal variation in bacterial skin communities and their maintenance for amphibian conservation efforts.

The role of biotic and abiotic factors in the distribution limits of an invasive grass

Authors: Rebecca Fletcher1, Daniel Atwater1, David Haak1, and Jacob Barney1

Affiliations: 1. Department of Plant Pathology, Physiology, and Weed Science, Virginia Polytechnic Institute and State University, Blacksburg, Virginia

Since before the time of Darwin, there has been an interest in species distributions and why species are found where they are. Range limits are strongly associated with both abiotic factors (e.g., temperature, precipitation) and biotic factors (e.g., competition, predation), but it is still unclear how much each of these factors influence species’ ranges. Recently, in light of global change, there has been a resurgence of interest in species distributions as the need to accurately predict how species will respond to climate change becomes ever more important. This need is especially important when considering invasive species, as evidence indicates that some invasive species may be expanding their ranges in response to climate change. The invasive Johnsongrass (Sorghum halepense) is a highly damaging weed and invader of natural ecosystems that has a wide, global distribution; however, there is evidence that climate may play an important role in limiting its range. We are investigating the influence of climate and competition on the range limits of Johnsongrass through the use of reciprocal common gardens in 5 locations–New York, Virginia, Georgia, Texas, and New Mexico–that represent the peripheral, edge, and core of Johnsongrass’ US distribution along both a temperature (NYàVAàGA) and precipitation (GAàTXàNM) gradient. Each common garden will have a no competition and a competition treatment. This design enables us to investigate the potential biotic and climate drivers of Johnsongrass’ distribution limits. Our work will advance our understanding of the factors that influence the distribution and abundance of invasive species.

Global change impacts on microbiome mediated plant-pollinator interactions.

Authors: Ariel Heminger 1 and David Haak 1

Affiliations: 1. Department of Plant Pathology, Physiology, and Weed Science, Virginia Polytechnic Institute and State University, Blacksburg, Virginia

Pollinators form the cornerstone of ecosystem stability and agricultural production and they are under threat from multiple global change factors which lead to precipitous declines in pollinator health. Recent declines in bee health have been associated with changes in gut microbial communities. Additionally, bee gut microbiomes leave a ‘footprint’ on flower microbiomes, however, little is known about the reciprocal effects of the floral microbiome on bee gut microbial communities, nor the impacts of global change factors in shaping these interactions. Here we compare reciprocal microbiome responses in pollinators and flowers across a latitudinal gradient (a surrogate for elevated temperature) and between native and non-native Solanum species. First, we will assess the structure of the floral microbiome during floral development and assess how they correspond with changes in pollinator gut microbial communities. Next, flowers on both species will be caged to exclude pollinators to determine how pollinators are impacting the floral microbiome in each species. The analysis of microbial communities in both plant species and their pollinators will be conducted through sequencing the 16s rRNA gene and ITS region as appropriate. Plant fitness will be assessed and determined how it relates to floral microbiome. This study will provide information regarding differences between native and non-native species microbial communities, how changes in floral microbiome structure impact pollinators, and how changes in environmental factors shape plant-pollinator microbiome interactions.

Sexually transmitted microbes as a cost of extra-pair activity in female tree swallows

Authors: Jessica Hernandez 1 and Ignacio Moore 1

Affiliations: 1. Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia

Up until the 1980s, most avian species were considered to be truly monogamous. It was not until the recent advent of revolutionary genetic approaches that the opposite pattern was shown to be true of avian mating systems. Species that were previously recognized to be truly monogamous were found to have extra-pair young, thus exhibiting evidence for extra-pair copulations. Fundamental questions in biology center around understanding the advantages and disadvantages of monogamy versus polygamy, particularly with regards to females and polyandry. While females face numerous potential fitness trade-offs (e.g., benefits: good genes, genetic diversity in offspring; costs: loss of paternal care, de novo deleterious mutations), I will focus on the sexual transmission of pathogenic microbes, which has been suggested to be a cost of extra-pair copulations to females since as early as the 1970s, but has not yet been adequately tested. For my dissertation, I will study a free-living, box-nesting population of polyandrous female tree swallows (Tachycineta bicolor) that form a social pair bond with a male throughout the breeding season, yet also engage in extra-pair copulations. Through observational and experimental studies, this project will help elucidate the relationship between extra-pair copulations and the presence, prevalence, and pathogenicity of sexually transmitted cloacal microbiota, with respect to fitness, in a wild avian population. Overall, such research is essential since host fitness consequences of sexually transmitted microbes likely influence sexual selection and the evolution of mating systems.

Implications of a changing climate on bird development

Authors: Sydney F. Hope 1, Sarah E. DuRant , Robert A. Kennamer 3, William A. Hopkins 1

Affiliations: 1. Department of Fish and Wildlife Conservation, Virginia Polytechnic Institute and State University, Blacksburg, VA; 2. Department of Integrative Biology, Oklahoma State University; 3. Savannah River Ecology Lab, University of Georgia

Our changing climate may pose a threat to the early developmental environment of animals. The effect of climate change on developing reptiles is well-studied, and there is evidence that changes in incubation temperature can have substantial effects on offspring. In contrast, the effects of temperature changes on bird phenotypes have been historically overlooked because parents regulate incubation temperature. However, studies have shown that changes in the environment can affect avian parental incubation behavior, and that small changes in incubation temperature can affect avian offspring phenotypes. Yet, few studies have investigated how environmental changes may directly and indirectly influence incubation temperature, and no studies have investigated how incubation temperature influences avian offspring behavior. We used wood ducks as a model system to address these questions. Our results show that wood duck nests with the largest clutch sizes and the lowest ambient temperatures led to the lowest incubation temperatures. We also found that ducklings incubated at 35 and 37°C exhibited bolder and more exploratory behaviors than those incubated at 35.8°C, while those incubated at 35°C were less successful at exiting the nest (a crucial behavior for wood duck ducklings) than those incubated at the other two temperatures. This research shows that environmental changes influence avian incubation temperature and thus, may influence offspring behaviors that are critical for survival. In this case, warming temperatures may be beneficial to developing birds, but future work should address how extreme weather events or changes in food availability due to climate change affect incubation temperature.

A Division of the Crown: using novel tracking devices to examine behavioral responses to fragmentation and habitat heterogeneity in crowned lemurs (Eulemur coronatus)

Authors: Meredith Keeley1, Ignacio Moore1, and Nicole Abaid2

Affiliations: 1Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia; 2Biomedical Engineering and Mechanics, Virginia Polytechnic Institute and State University, Blacksburg, Virginia

Madagascar, an island off the coast of southeast Africa, is one of the world’s “richest” biodiversity hotspots, yet little is known about how habitat degradation will affect imperiled species. Crowned lemurs (Eulemur coronatus), listed as endangered on the IUCN red list, are frugivorous, group living, cathemeral primates endemic to forests of northern Madagascar. Crowned lemurs display a flexible behavioral strategy called fission-fusion, which results in individuals periodically separating from group members (fissions) and rejoining after temporal and spatial separation (fusions). We are seeking to examine how fragmentation and landscape heterogeneity influence fission-fusion dynamics in this species. However, studying primates when groups are constantly fluctuating in size and composition is nearly impossible due to logistical challenges and the high cost of commercially available tracking equipment. To address this issue, we propose to design a modular, open-source tracking collar. Our monitoring device, nicknamed FitPET (“FITness, Proximity, Energetics, and Tracking”), will be capable of capturing data on lemur social and spatial behavior. The tracking devices will be specialized to collect precise measurements of proximity between group members, grooming frequency, locomotion, and heart rate. The outcome of the project will be the development of technology, synergizing the fields of biology and engineering, to better understand crowned lemur social interactions and transform the ways in which wildlife species are studied.

Urbanization and parental care: Are parents able to compensate for changing ecological conditions?

Authors: Samuel Lane 1, Kendra Sewall 1

Affiliation: 1. Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia

Phenotypic plasticity is an organism’s ability to adjust its phenotype in response to habitat variation. Such plasticity has been proposed to help organisms cope with changing environmental conditions. Additionally, parental care is a mechanism that could buffer developing young from environmental variation with consequences for their mature phenotype. For my dissertation, I will compare phenotypic outcomes of free-living, urban and rural song sparrows to better understand how variation in habitat quality affects growth and development.  I will use observational and experimental approaches to study the following objectives: 1) To determine the level of developmental stress offspring experience, I will measure nestling growth and stress hormone levels through development. I predict that offspring’s in urban habitats will experience pathological stress during development. I predict that urban habitats will be of lower quality due to food restriction and anthropogenic stressors. 2) To determine the extent to which parental care may mitigate ecological variation, I will use video recordings of the nest to measure feeding rates and food load. I predict that parents in urban environments will increase parental care when possible but prioritize territorial behaviors. Collectively, these studies will resolve how urbanization affects the phenotype and fitness of developing birds. Urbanization represents a dramatic and relatively quick change in environment. Understanding how environmental factors impact birds’ phenotypes, if parental care provides a buffer to ecological change, and the fitness consequences of urbanization will inform conservation efforts.

Advancing equity: Comparing water violations in rural versus urban Virginia

Authors: Cristina E. Marcillo 1, Leigh-Anne Krometis 1

Affiliations: 1. Department of Biological Systems Engineering, Virginia Polytechnic Institute and State University, Blacksburg, Virginia

The Safe Drinking Water Act (SDWA) of 1974 and its subsequent amendments have revolutionized the way that drinking water is protected in the United States. However, high profile failures, such as the lead crisis in Flint, Michigan, have cast doubt on the equity and reliability of these regulatory mechanisms. Previous studies using publically available compliance data have found that regulatory inequities regarding water quality and availability do exist based on system size, race, ethnicity, and low socioeconomic status of the community served. However, the effects of urbanity and rurality on drinking water system integrity has only been cursorily characterized. This work seeks to identify and describe primary differences in drinking water challenges in urban and rural American landscapes. The work to be presented is an illustrative case study comparing drinking water violation patterns in distressed rural Appalachia counties versus coastal Virginia cities designated as environmental justice hotspots. Initial comparisons suggest that rural Virginia counties are served by five to twelve times the number of water systems as the two independent cities, despite serving less than twenty-five percent of these cities’ population. More notably, over one hundred times the number of SDWA violations were reported within the rural region as compared to the independent cities within the last ten years. Ongoing work is expected to expand this case study method to the entire southeast region of the United States. This study has implications for the way that public water systems are managed and regulated across disparate regions of the United States. This work also has value for rapidly urbanizing developing nations who must manage their drinking water infrastructure for a growing urban and peri-urban population.

Metalimnetic oxygen minimum zones decouple diffusive CH4 and CO2 fluxes from seasonal turnover in a eutrophic reservoir

Authors: R.P. McClure1, M.E. Lofton1, K.D. Hamre1, B.R. Niederlehner1, Z.W. Munger2, S. Chen3, J.P. Doubek1, M.E. Schreiber2, and C.C. Carey1

Affiliations: 1. Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia; 2. Department of Geosciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia; 3. Department of Civil Engineering, University of Sydney, Sydney, Australia

Diffusion of greenhouse gases (GHGs) from freshwater ecosystems into the atmosphere can contribute a large fraction of total GHG efflux. In temperate waterbodies, annual peak diffusive flux generally occurs during fall turnover when methane (CH4) and carbon dioxide (CO2) in the anoxic bottom layer (the hypolimnion) mix to the surface. However, when thermal stratification develops, some waterbodies become anoxic in the middle of the water (the metalimnion), not the hypolimnion. This can change the distribution of pCH4 and pCO2 in the water column and alter diffusive CH4 and CO2 efflux phenology. As a part of water quality management in a local reservoir, an anoxic metalimnion (OMZ) has developed since 2013. We measured depth profiles of dissolved CH4 and carbon dioxide (CO2) concentrations since 2015, and estimated CH4 and CO2 atmospheric gas exchange with multiple gas flux models. We observed substantial accumulation of CH4 within the OMZ of the local reservoir in summers 2015 and 2016. Regardless the gas flux model, the largest efflux of CH4 into the atmosphere was decoupled from turnover both years, while peak CO2 efflux from the hypolimnion occurred during turnover. Thus, timing and magnitude of GHG fluxes may be dependent on the depth of the gases in the water column, and that the efflux of gases in the metalimnion may be sensitive to extreme events that are decoupled from turnover. If OMZs increase as a result of global change, waterbodies may accumulate substantial concentrations of CH4 in their water columns, thereby altering the GHG efflux phenology.

Resource use and interspecific interactions in a cavity-nesting guild in central Namibia

Authors: David Millican 1, Mark Stanback 2, Jeffrey Walters 1

Affiliations: 1. Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia; 2. Department of Biology, Davidson College, North Carolina

Cavity-nesting guilds are hierarchical communities of vertebrates and invertebrates that interact through competition for nest sites. Some species in these communities, known as primary excavators, are able to create their own nest cavities. Other species, known as secondary nesters, rely on pre-existing cavities to breed, be they cavities made by excavating species or by other natural processes. Due to their dependence on pre-existing cavities, secondary nesters are highly susceptible to forms of disturbance that diminish the availability of suitable nest cavities, including anthropogenic management and natural disasters. Quantifying the entirety of a cavity guild’s structure is critical to understanding how to conserve that community. To inform land managers on how to preserve Namibia’s threatened cavity-nesting guild, we have embarked on a nest-web analysis outside Otjiwarongo in central Namibia. We are two years into a study that aims to evaluate the availability of the central resource (tree cavities), primary forms of cavity creation, species-specific cavity preferences, and interactions between cavity-nesters, including direct competition for nest sites and indirect interactions as cavities are used over time. Preliminary results suggest that cavity density overall is low, with natural cavities (12.4/ hectare) 15 times more abundant than excavated cavities (0.8/hectare), and that large cavities are in particularly low supply. Some small-bodied secondary nesters readily use excavated cavities, suggesting that excavating species, though in low densities, may act as ecosystem engineers in this ecosystem. Large-bodied secondary nesters, of which there are over a half dozen species, are particularly likely to be restricted by cavity availability, as they utilize a limit supply of naturally formed cavities. Already facing intense competitive pressures, cavity-nesting populations could face declines due to pressures resulting from common management practices, such as charcoal production, as well as from climate change induced droughts, which may hinder floral growth, and thus the replacement of large, cavity-bearing trees. Results of this study will inform management plans and aid local conservation efforts targeting cavity-nesting species, some of which may risk extirpation from Namibian forests.

Natal dispersal patterns and behavior in juvenile male Red-cockaded Woodpeckers

Authors: Leah D. Novak1, Jeffrey R. Walters1, and Dylan C. Kesler2

Affiliations: 1. Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg; VA. 2. The Institute for Bird Populations, Point Reyes, California

Natal dispersal, the movement of an individual animal from its birth site to its breeding site, is primarily governed by resource quality and availability, and intraspecific competition for that resource. Natal dispersal can be costly, therefore juveniles often use a prospecting strategy to gain knowledge regarding the conditions outside their natal territory before permanently leaving. The Red-cockaded Woodpecker (RCW) is a cooperatively breeding, federally listed, endangered species endemic to open, southern pine savannah of the Atlantic and Gulf Coastal Plains. Juvenile male RCWs employ two natal dispersal strategies to cope with limited availability of resources, mainly cavities: the dominant males delay dispersal and remain on their natal territory as non-breeding helpers and the subordinate males disperse their first year. Juvenile female RCWs usually disperse, but prospect extensively before leaving. It is unknown if dominant and subordinate juvenile males also prospect. In this study, I investigated dispersal behavior, specifically prospecting behavior, in dominant and subordinate juvenile male RCWs in coastal NC. I followed 9 subordinate and 11 dominant juveniles before and during the breeding seasons (February – June) of 2015 and 2016 using radio telemetry and GPS while they prospected alone and while they foraged with their families. I then determined the distance and direction of forays and calculated the likelihood that a juvenile RCW would travel through certain cover types or near other conspecifics. Overall, subordinate males tended to prospect often and avoided other clusters, while dominant males tended to prospect less.

You can’t plant generic trees

Authors: Joshua M. Rady 1, Benjamin J. Ahlswede 1, R. Quinn Thomas 1

Affiliations: 1. Department of Forest Resources and Environmental Conservation, Virginia Polytechnic Institute and State University

It is well established that forests play a major role in global climate.  Trees take up ~30% of anthropogenic carbon dioxide, decreasing the warming impact of human emissions.  For this reason, forests play a role in many global warming mitigation approaches through reforestation and afforestation.  Current global climate models use simplified representations of forests that do not provide information critical to planning actual mitigation efforts.  Planting forests is not a binary decision.  You must also determine which species to plant, where, and what if any management to invoke.  We are currently working to improve a widely used global earth system model (NCAR’s CESM1.2 / CLM5) by incorporating more realistic representations of forest management and tree species.  With these improvements, we hope to answer several consequential questions:  Does forestry management impact the climate services provided by forests?  Which sequester more atmospheric carbon, natural or plantation forests?  What management activities might be employed to increase climate benefits?  What species should be planted and where to achieve certain climate goals?  Are the effects of some management actives, such as fertilization and irrigation, counteracted by downstream ecological effects?  The answers to these questions should be directly relevant to decision makers in the climate policy arena.

Individual variation in testosterone and cooperative behavior in a neotropical lekking bird, the Wire-Tailed Manakin

Authors: Ben Vernasco 1, Ignacio Moore 1, Brent Horton 2, & T. Brandt Ryder 3

Affiliations: 1. Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia, 2. Millersville University, 3. Smithsonian Migratory Bird Center

­Manakins of the family Pipridae are known for performing complex courtship displays at leks. These complex displays have evolved in association with strong reproductive skew, suggesting individual differences in courtship behavior exist. By measuring components of hormone regulatory networks, one may be able to elucidate the proximate mediators of individual variation in courtship behavior. To date, however, work documenting the relationship between individual variation in reproductive behavior and circulating steroids in manakins has been inconclusive. Here, using video recordings of male territories and subsequently collecting a blood sample, we quantified the relationship between individual variation in reproductive behavior and circulating testosterone in male wire-tailed manakins (Pipra filicauda). In this system, previous research has shown that territory-holding males have higher testosterone than floaters (i.e., non-territory-holding males), implying that testosterone plays a role in territory acquisition and maintenance. Our results show that that males with a higher proportion of cooperative displays (an important predictor of male wire-tailed manakin reproductive success) perform longer displays. However, males with high circulating testosterone engage in fewer cooperative display bouts suggesting that high levels of testosterone may interfere with effective cooperative behavior and result in shorter display bouts. These results suggest that individual differences in circulating testosterone levels play an important role in mediating individual variation in male reproductive behavior and potentially success. This research ultimately adds to our knowledge about the proximate mechanisms that mediate individual variation in both reproductive and cooperative behavior.

Identifying early warning indicators of eutrophication to inform real-world management: engaging long-term data, ecosystem modeling, committed citizen scientists, and remote sensing

Authors: Nicole K. Ward 1, Bethel Steele 2, Kathleen C. Weathers 2, Kathryn L. Nottingham 3, Holly A. Ewing 4, Paul C. Hanson 5, Robert Wood 6, June Fichter 6, Cayelan C. Carey 1

Affiliations: 1. Virginia Tech, Department of Biological Sciences, Blacksburg, Virginia, 2. Cary Institute of Ecosystem Studies, Millbrook, New York, 3. Dartmouth College, Department of Biological Sciences, Hanover, New Hampshire, 4. Bates College, Program in Environmental Studies, Lewiston, Maine, 5. University of Wisconsin-Madison, Center for Limnology, Madison, Wisconsin, 6. Lake Sunapee Protective Association, Sunapee, New Hampshire

Freshwater lakes integrate the cumulative impact of upstream human activities on water quality, and thus early warning indicators (EWIs) of ecosystem change in lakes may be used to understand the impact of environmental changes in their catchment. EWIs are statistical metrics applied to high-temporal frequency data to predict regime shifts. To date, EWIs have been used to retroactively assess observed regime shifts and to reverse algal blooms in lakes, but they have not been widely used to inform real-world management decisions. Here, we explored the use of EWIs in water quality management by addressing the questions: 1) How are land use and climate change interacting to affect water quality in an oligotrophic lake over three decades? and 2) Can we use EWIs to manage water quality in a real-world oligotrophic lake? We used historical and recent GLEON (Global Lakes Ecological Observatory Network) buoy sensor data on Lake Sunapee, New Hampshire (USA), collected primarily by committed citizen scientists, to calibrate a lake ecosystem simulation model (General Lake Model; GLM) run at an hourly time step for three decades. We then tested for EWIs in the model output using a suite of statistical analyses, including breakpoint analysis, rolling standard deviation, and autocorrelation. The EWI assessment and simulated lake response to nutrient loading using GLM provide a suite of alternative scenarios as a tool to assist management. Our next steps are to assess land cover change using Landsat imagery and develop spatially-explicit nutrient loading model scenarios to predict future lake water quality

Ecological effects of livestock antibiotics on agricultural soils

Authors: Carl Wepking 1, Brian Badgley 2, Jeb Barrett 1, Matt Hedin 1, Katharine Knowlton 3, Kevan Minick 4, Partha Ray 5, Mike Strickland 1

Affiliations: 1. Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia; 2. Department of Crop and Soil Environmental Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia; 3. Department of Dairy Science, Virginia Polytechnic Institute and State University, Blacksburg, Virginia; 4. Department of Forestry and Environmental Resources, North Carolina State University, North Carolina; 5. School of Agriculture Policy and Development, University of Reading, Berkshire, United Kingdom

Antibiotic use is under increased scrutiny due to their declining effectiveness; this includes the use of antibiotics in livestock production, which accounts for 80% of national antibiotic use. Much of this 80% passes through livestock via manure, with high estimates at approximately 14-million kg-yr-1. Studies have shown that additions of manure from cattle treated with antibiotics can have effects on soil microbial community composition, antibiotic resistance gene (ARG) abundance, and ecosystem functioning. However, studies have also shown that additions of manure from cows receiving no antibiotics can also cause increases in ARGs. To better understand the relative contribution of manure and antibiotics, a common garden experiment was established where plots were amended with manure from cattle either treated with one of two types of antibiotics, or untreated cattle. Manure was added monthly for three years. Each spring, plots were pulse-labeled using 13C and 15N. Soils and plant biomass from these plots were collected and analyzed using a range of assays to better understanding how soil microbial communities are impacted by manure as well as antibiotics. We have found that manure type does have an impact on a number of important microbial parameters. For instance, manure from cattle treated with the antibiotic pirlimycin elicited an ~6,000 kg ha-1 y-1 increase in respired carbon compared to manure from cattle treated with cephapirin. Although further analysis needs to be completed, the results from this field study highlight the potential influence antibiotics and the type of antibiotics have on soil and ecosystem processes.

Life history and ecology of the endangered Bahama Swallow (Tachycineta cyaneoviridis)

Authors: Maya Wilson 1 and Dr. Jeff Walters 1

Affiliations: 1. Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia

The Bahama Swallow (Tachycineta cyaneoviridis; BAHS) is an endangered species that is endemic to three islands in the northern Bahamas. Very little is known regarding the abundance, distribution or dispersal among islands of BAHS, or the factors responsible for the species’ decline. We are assessing the current population biology of BAHS using population surveys and genetic-based methods, and expanding the limited life history data available by locating and monitoring BAHS nests. Preliminary results show that BAHS breed between April and July, laying an average of three eggs in pre-existing cavities, primarily abandoned woodpecker cavities in snags of Caribbean Pine (Pinus caribaea) and utility poles, and holes in cell phone towers and buildings. Bahamian pine forests were heavily logged through the early 1970s; work to date suggests availability of nest sites limits populations, and reductions in this resource may be responsible for the species’ decline. We are conducting surveys of the pine forest and other habitats to assess the availability of cavity-nesting resources across the landscape and constructing a cavity-nest web illustrating species interactions. BAHS appear to rely on West Indian Woodpeckers (Melanerpes superciliaris) and especially Hairy Woodpeckers (Picoides villosus) to excavate cavities, and compete with secondary cavity-nesters including the American Kestrel (Falco sparverius), La Sagra’s Flycatcher (Myiarchus sagrae), House Sparrow (Passer domesticus) and European Starling (Sturnus vulgaris). By working with local organizations to facilitate and promote this work, our ultimate goal is to provide information that can be used develop conservation strategies for BAHS and their breeding habitat.

Detailed AGENDA PDF

Thursday, April 21, 2016

Keynote Lecture:
Dr. Josh Tewksbury, Future Earth
Lyric Theatre, 4:45-5:45 pm
Private reception to follow
~~~~~~~~~~~~~~~~~~~~~~~

Friday, April 22, 2016

8:30 a.m. IGC IGEP Breakfast Forum
with Dr. Josh Tewksbury
Old Guard Dining Room, Preston’s 
Graduate Symposium:
Fralin Hall, 12:00-6:30 pm
11:15 Poster setup
12:15 Posters & Coffee
1:00 Welcome: Dr. Bill Hopkins, Director, Global Change Center
1:05 Opening Remarks: Dr. Karen DePauw, Vice President for Graduate Education and Dean of the Graduate School
1:30 Platform Session 1; Session Chair: Laura Schoenle
2:30 Posters & Coffee
3:00 Platform Session 2; Session Chair: Tamara Fetters
4:15 Poster Reception (students by posters)
6:00 Platform Award Announcements
6:30 Adjourn

All IGC fellows are encouraged to present their work at the symposium. First-year students will give posters on their proposed research/study design; second- and third-year students have the option of presenting either a poster or a talk. Awards will be given for best talks.

Please submit your abstracts to Gloria Schoenholtz (schoeng@vt.edu) by March 28, 2016.  Each abstract should contain 1) Title, 2) Authors and affiliations (e.g., Dept and University), and 3) an abstract not to exceed 250 words in length.

For posters: maximum poster size is 40″ x 60″.  An easel and backboard will be provided.

The Influence of Social Behavior and Stability on Disease Transmission in a Songbird Host

Authors: Matt Aberle1 and Dana Hawley1

Affiliations: 1. Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia

Social interaction in animals has been shown to have lots of fitness benefits, like cooperation in foraging and sharing of resources. However, species that have lots of social interaction are also at a much higher risk of transmitting infectious diseases. Therefore, it is important to study not only social behavior itself, but the structure and stability of social groups as well. Past studies have shown that not only does social stability and behavior change an animal’s exposure to disease, but it can impact physiological factors influencing disease susceptibility through both stress responses and changes in hormones as well. A relatively new method for analyzing social behavior and disease transmission is through contact network modeling. Contact networks show the interactions between individuals within a population and can be created using technology like radio-frequency or GPS. These networks can also give information on how interactions are changing over time as well making them a dynamic tool. Since the early 1990s house finches have been subject to a highly infectious bacterium causing conjunctival pathology. Finches form flocks outside of the breeding season and congregate at bird feeders where the majority of transmission takes place, thus they are an ideal system to test hypotheses relating to social behavior, stability, structure and the impacts of those behaviors on disease transmission. I plan to do my dissertation research on this system utilizing RFID technology placed on feeders to see how manipulations of house finch social behavior and stability affects disease transmission, prevalence, and severity.

The Two Towers: An ecosystem story as told by the atmosphere

Authors: Ben Ahlswede1, Quinn Thomas1, Tom O’Halloran1

Affiliations: 1. Department of Forest Resources and Environmental Conservation, Virginia Polytechnic Institute and State University, Blacksburg, Virginia

How do we combat climate change? One potential solution is to change our source of energy, from fossil fuels to bio-fuels. Biofuels, have a shorter carbon cycle than fossil fuels, allowing for complete reabsorption of burned fuel within a hundred years as opposed to ten thousand. However, sources of biofuel such as Switchgrass and Loblolly pine have other effects on climate besides absorbing carbon. They also affect the planetary energy balance by altering the reflectivity of the Earth’s surface, and altering how energy is distributed through the atmosphere. These processes have the ability to affect local and regional temperature and can counteract any benefit derived from reduced CO2 in the atmosphere. We have partnered with Sweet Briar College and the Global Change Center to set up two eddy flux covariance systems on the Sweet Briar campus, one over a loblolly stand, and one over a switchgrass field. These paired systems will independently measure fluxes of carbon and water, as well as incoming and outgoing radiation, photosynthetically active radiation, temperature, humidity, precipitation, soil temperature, soil moisture, and energy absorbed by the ground. These measurements will allow us to compare these systems as potential biofuels in a complete accounting of how they affect climate. In addition, data from these towers can be used to inform and constrain future work investigating the effects of implementing a biofuel program on a regional and global scale.

Identifying local strains of Nile tilapia Oreochromis niloticus that are adapted to future climate conditions

Authors: Gifty Anane-Taabeah1,2, Emmanuel Frimpong1, Stephen Amisah2, Akwasi Ampofo-Yeboah3, and Eric Hallerman1

Affiliations: 1. Department of Fisheries and Wildlife Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia; 2. Department of Fisheries and Watershed Management, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana, 3. Department of Fisheries and Aquatic Resources Management, University of Development Studies, Nyankpala Campus, Ghana

This study was conducted to synthesize information on the ambient water quality (temperature, dissolve oxygen and salinity) for the Nile tilapia, an important commercial species, compare wild populations in the Volta basin and the selectively bred Akosombo strain from the basin used in fish farming in Ghana under current and future climate conditions, and develop predictive models delineating the boundaries of the species’ range. A combination of literature survey, field and laboratory methods provided data for meta-analysis, growth and genetic analysis, as well as distribution models. We found variations in water temperature along the latitudinal gradient in Ghana; and temperature was the most informative variable in terms of characterizing the adaptive range and ambient water quality for the species. The results of the growth studies showed no evidence of superior performance of the Akosombo strain over the wild strains under current or predicted future climatic conditions of temperature, dissolved oxygen, or salinity. Significant Fst values from the genetic analysis suggested that the Akosombo strain was well differentiated from all the wild populations (Aframso, Sabare and Binaba) studied. The combined results of the field, growth and genetic studies show that at least one wild population from the Oti River (Sabare) may possess the traits for superior performance under high temperature and low DO conditions. Further studies should concentrate on comparing the Sabare strain with the Akosombo strain under different experimental conditions and increase replications to confirm the suggested differences and the heritability of those performance traits for selective breeding.

What’s Bugging the Bugs? Commonalities in Benthic Stressors across the United States

Authors: Heather Govenor1, W. Cully Hession1, Leigh-Anne Krometis1

Affiliations: 1. Department of Biological Systems Engineering, Virginia Polytechnic Institute and State University, Blacksburg, Virginia

Biological monitoring of invertebrate communities is a key component of stream monitoring under the Clean Water Act in nearly all states, and is one approach used to determine if the biological integrity of state waters is being protected. Monitoring methods, interpretation of field data, and metrics used to evaluate invertebrate communities vary widely across the county, and flexibility in reporting requirements results in inconsistencies in how invertebrate-based impairments are reported to the EPA. Further, states differ in the specific approaches used to determine Total Maximum Daily Loads (TMDLs) to address the stressors associated with impairments. The objective of this research was to determine the pollutants most commonly associated with invertebrate-based stream impairments in the U.S. Through discussions with EPA and state regulators, and evaluation of over 1000 approved TMDL reports written since the initiation of the TMDL program, we confirm a long-thought but formerly undemonstrated assumption that sediment is the most commonly identified stressor associated with invertebrate-based stream impairments nationwide. The variety of approaches used to identify sediment TMDLs are discussed.

Millipedes Under Our Feet: Taxonomic Revisions of the Common North American Millipede Genera Pseudopolydesmus(Polydesmida: Polydesmidae) and Nannaria (Polydesmida: Xystodesmidae)

Authors: Derek A. Hennen1 and Paul. E. Marek1

Affiliations: 1. Department of Entomology, Virginia Polytechnic Institute and State University, Blacksburg, Virginia

Much progress in North American millipede taxonomy has been made over the past three decades, stabilizing nomenclature and providing identification resources. However, much work remains, particularly with regards to alpha-taxonomy and revisions of poorly-understood groups. In eastern North America, the two genera Pseudopolydesmus (Polydesmida: Polydesmidae) and Nannaria (Polydesmida: Xystodesmidae) are among the most commonly encountered millipedes, with 12 and 23 described species, respectively. However, species level classification in Pseudopolydesmus is fuzzy and in need of revision. Nannaria has many undescribed species represented in museum collections, and may even double the number of currently known species. To remedy this, molecular and morphological studies are being conducted to revise the genera and describe new species. Collecting is being done in areas throughout the eastern United States to obtain fresh specimens for molecular analysis and to search for new species, and museum specimens are being examined for morphological analysis. As a result of these studies, photographs and identification keys will be produced, and new species and their ranges will be described.

Effects of social environment on the development and maintenance of behavioral strategies for coping with stress.

Authors: Kaan Kerman1 & Kendra Sewall1

Affiliations: 1. Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia

Coping styles are consistent behavioral differences in how individuals respond to stressful conditions. Proactive individuals are more likely to engage with potential dangers, while reactive individuals tend to avoid a threatening stimuli. Understanding the proximate mechanisms behind these contrasting strategies is an active area of research. In this dissertation project, we will explore one aspect of these proximate processes: mediating role of social environment on the development and expression of coping styles in a model species, the Zebra Finch (Taeniopygia guttata). Using behavioral responses in three different assays to characterize coping styles in our population, we will investigate how exposure to social stress in early development impact the emergence of coping styles later in life, and how social position within a group influence the expression of coping styles in adulthood. We predict that, exposure to stressful social conditions during development, as simulated by artificial injection of stress hormones in egg and hatchling stages (i.e. CORT), causes differential expression of two types of stress hormone receptors in the brain, which leads to a more reactive response later in life. In adulthood, we predict that individuals with strong associations within a flock, and higher dominance status, will be buffered from potential risks in an environment, resulting in a more proactive response even though their coping style is strongly shaped with early life social conditions. This study will have important implications on understanding the emergence of coping with stress as an interplay between epigenetic effects in early life and social conditions in adulthood.

Impacts of mining effluent on fishes in the Clinch River and Powell River watersheds

Authors: Zachary Martin1, Serena Ciparis1, Don Orth1, and Paul Angermeier1,2

Affiliations: 1.Department of Fish and Wildlife Conservation, Virginia Polytechnic Institute and State University, Blacksburg, Virginia; 2. U.S. Geological Survey, Virginia Cooperative Fish and Wildlife Research Unit, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 

Mining coal in Appalachia has profoundly changed landscapes and impacted >1,900 km of headwater streams. Mining activities can increase instream sedimentation and elevate concentrations of total dissolved solids and trace elements (e.g. selenium) above tolerances of stream fishes. We are evaluating the fish response to mining effluent across a mining-intensity gradient in 16 headwater streams in the upper Powell River and the upper Clinch River watersheds. We expected conductivity, fine sediments, major ion concentrations and [Se] to be elevated in streams on the high-impact end of the gradient. Further, we expected to find fish responses such as shifts in community assemblage, reduced spawning performance, and reduced individual-level health at high-impact sites. Water quality, physical habitat, fish community, and fish tissue samples were collected August – October 2015. There were strong correlations between our mining gradient and measured specific conductivity and concentrations of HCO3–, Ca, Mg, Na, K, and SO42-. Seventeen fish species were collected and individual-fish data were gathered on two species, Etheostoma flabellare and Rhinichthys obtusus. A hierarchical cluster analysis characterizing species composition at sites identified two groups: widespread species (Campostoma anomalum, Rhinichthys obtusus, Etheostoma flabellare, and Semotilus atromaculatus) and patchily distributed species (all others). Although E. flabellare was widespread, it was absent from assemblages at four high-impact sites. Future interpretation of community data will be paired with physical habitat and water quality data. This spring we are also processing fish tissue samples to describe changes in individual-level health and conducting spawning surveys of E. flabellare across our mining-impact gradient.

Behavior and Impact of Spathius galinae and Spathius agrili on Emerald Ash Borer in Virginia

Authors: Max Ragozzino1, Scott Salom1

Affiliations: 1. Department of Entomology, Virginia Polytechnic Institute and State University, Blacksburg, Virginia

Emerald ash borer (EAB), Agrilus planipennis Fairemaire (Coleoptera: Buprestidae) is a wood-boring beetle native to Asia introduced to Michigan in 2002. In both its native range and in North America, EAB primarily feeds on ash trees (Fraxinus sp.). In North America, ash tree stands suffer complete mortality within 6 years of infestation, and it is estimated to kill 38 million ash trees by 2019. EAB larvae are frequently predated by native woodpeckers (Picidae), accounting for up to 39% of all EAB larvae in some areas. Four hymenopteran parasitoids have been identified in Asia and introduced to the U.S. as biological control agents against EAB. This study will focus on two larval parasitoids, Spathius agrili Yang (Hymenoptera: Braconidae), and Spathius galinae Belokobylskij and Strazenac (Hymenoptera: Braconidae). Neither parasitoid is established in Virginia. We plan to study competitive interactions between both parasitoid species, including multiparasitism and adult competition to determine the best course of action for establishment. We will release both parasitoids across Virginia at a variety of ash dense forest locations, and monitor their activity using a variety of methods including sentinel logs and total larval counts. Once establishment occurs, we will exclude woodpeckers from infested ash trees in order to determine the effect of woodpecker predation on the parasitoids.

Climate Change, Coups, and Critically Endangered Species: First Aerial Drone Surveys of Madagascar’s Lemurs

Authors: Brandon P Semel and Sarah M Karpanty

Affiliations: Fish and Wildlife Conservation Department, Virginia Polytechnic Institute and State University, Blacksburg, Virginia

Lemurs are found only in Madagascar and are earth’s most threatened mammals. Hunting, habitat loss, government instability, and climate change all pose serious threats to lemur species. Establishing baseline population estimates and enacting long-term population and habitat monitoring efforts to guide conservation strategies are critical to their survival. However, traditional survey methods are labor intensive, expensive, and can facilitate resource extraction. Novel technologies, such as aerial drones, will help to overcome these obstacles. Population estimates and threat quantification for diurnal species in northern Madagascar will be obtained summer 2016, including critically endangered golden-crowned sifakas (Propithecus tattersalli) and endangered crowned (Eulemur coronatus) and Sanford’s brown (E. sanfordi) lemurs. Prior to conducting drone surveys, lemur behavioral responses to their presence will be assessed so that surveys are performed in a way that minimizes animal stress. A cost-benefit analysis comparing line transects and aerial drone surveys will be conducted, fragments with extirpated lemur populations will be identified for future translocation, and land cover change will be mapped to aid in conservation prioritization and to establish a habitat baseline for future climate change studies. Partnering with Malagasy conservation initiatives will ensure continued long-term monitoring. Pilot data will facilitate my doctoral work investigating how lemurs in this region will respond to climate change-induced environmental change and aid in local conservation efforts in a global biodiversity hotspot. Results will be broadly applicable to wildlife management and conservation around the world.

Modeling Freshwater Salinity for Aquatic Biodiversity Management

Authors: Tony Timpano1, Stephen Schoenholtz1, David Soucek2, and Carl Zipper3

Affiliations: 1. Forest Resources and Environmental Conservation, Virginia Polytechnic Institute and State University, Blacksburg, Virginia; 2. Illinois Natural History Survey, U. Illinois Urbana-Champaign; 3. Crop and Soil Environmental Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia

Human activities like agriculture and resource extraction can increase the dissolved inorganic ion concentration (i.e., salinity) in waterbodies, creating toxic conditions for life adapted to dilute freshwater. This salinization of freshwaters is a global threat to aquatic biodiversity. In the USA, mountaintop coal mining contributes to salinization of headwater streams in the Appalachian region, a biodiversity hotspot. Recently, water quality managers have sought to mitigate the biotic effects of salinization by determining the limits of salinity tolerable to freshwater organisms. To date, limits have been based on salinity-biota relationships observed in field surveys that measured salinity only once per year. However, because salinity can vary with seasonal stream flow, effective management will require understanding the temporal patterns. Toward that end, we measured the salinity surrogate electrical conductivity continuously for three years in 25 minimally-disturbed headwater streams across a gradient of salinity in the Appalachian coalfields of Virginia and West Virginia. We found that salinity changed throughout the year, in a distinct seasonal pattern in nearly all streams, regardless of mean annual salinity level. We modeled the pattern using a sine-cosine linear model and found moderate to strong fits. The models indicated that annual minimum salinity occurred in spring and annual maximum salinity occurred in autumn. Averaged across all sites, seasonal deviations from mean annual salinity reached approximately 20% in spring and autumn. Our models indicate substantial, yet predictable seasonal variation in salinity, which should improve salinity management to achieve aquatic biodiversity goals.

Subtle variation in incubation temperature may have long-term effects on immune function and sexually-selected traits of an altricial model, the zebra finch

Authors: J. Wagner1, M. Beck2, E. Joseck3, W. Hopkins1

Affiliations: 1. Department of Fish and Wildlife Conservation, Virginia Polytechnic Institute and State University, Blacksburg, Virginia; 2. Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia; 3. Department of Animal and Poultry Science, Virginia Polytechnic Institute and State University, Blacksburg, Virginia

Avian incubation temperature plays an important role in offspring development and is affected by the interaction between parental behavior and environmental variables. Numerous studies have indicated its importance to a suite of phenotypic traits in offspring, yet we have a fairly limited understanding of how variation in incubation temperature affects individuals throughout adulthood. The literature has identified numerous traits that are affected in altricial nestlings prior to fledging and in precocial birds (chickens and ducks), but whether or not incubation temperature has long-lasting impacts on individuals, possibly affecting their lifetime phenotypic trajectory, is unknown.  We investigated how growth, immune function, and ornamental plumage was influenced by variation in incubation temperature by incubating eggs at two biologically-relevant temperatures (36.5 and 37.5°C) and measuring endpoints on nestlings and adults. We found no differences in growth or immune function in young birds across the two incubation temperatures. However, compared with 37.5°C individuals, those incubated at 36.5°C had a lower cell-mediated immune response as adults (40 days post-hatch) and males had lower brightness and intensity ornamental plumage coloration at sexual maturity (~100 days post-hatch). This study demonstrates how subtle differences in the conditions experienced during embryonic development may have a crucial and long-lasting influence on individual phenotype.

A Comparison of Intraspecific Aggression in Populations of the Lizard, Anolis sagrei, at Varying Stages of Species Invasion

Authors: Julie M. Wiemerslage1 and Joel McGlothlin1

Affiliations: 1. Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia

It is important to asses how invasive species are able to thrive in novel environments in order to predict and prevent future invasions. Additionally, the study of invasive species allows a unique opportunity to assess how species adapt to novel conditions, which are often created by current global changes. Invasive species often undergo phenotypic divergence from their native counterparts because they must adjust to novel conditions to persist outside of their native range. Behavior is a key determinant of success for invasive animals because it can facilitate rapid responses to novel conditions, so it is likely that behavioral divergence occurs in species invasions. Anolis sagrei is an invasive territorial lizard in the Southeast United States that is native to the Caribbean. For A. sagrei and other territorial species, increased territorial aggression may be selected for when their ranges expand into areas that contain closely related species. This study investigates the differences in aggressive behavior between populations of A. sagrei at different stages of invasion. One-on-one aggressive encounters were staged between males in order to assess differences in aggressive behavior between different populations. We had two competing hypotheses: 1. lizards at the front of the range are more aggressive than other populations because aggression allows them to outcompete species in their new range, and 2. lizards at the front of the range are less aggressive than other populations because there is lower population density there, thus less competition.

Population biology, life history, and ecology of the Bahama Swallow (Tachycineta cyaneoviridis): informing conservation of an endangered bird in the northern Bahamas

Authors: Maya Wilson1 and Jeffrey Walters1

Affiliations: 1. Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia

The Bahama Swallow (Tachycineta cyaneoviridis) is an endangered bird species that is endemic to the northern Bahamas. This doctoral research project focuses on three central questions:

• What are the features of the current Bahama Swallow population biology? Available population estimates indicate a sharp decline in population abundance, and there is currently no information regarding distribution and dispersal. I am conducting surveys and using capture-recapture to estimate abundance and distribution, and taking genetic samples to assess the dispersal of populations between islands.
• What are the life history characteristics of the Bahama Swallow? The life history data for this species are limited, and I am expanding these data by monitoring active nests during several consecutive breeding seasons.
• What are the potential agents of decline of Bahama Swallow populations? (A) Habitat loss and degradation: Bahamian pine forests were heavily logged, and continued loss and degradation of pine forests poses an ongoing threat. I am conducting habitat surveys to assess the availability of suitable breeding habitat. (B) Competition for nesting cavities: The Bahama Swallow may face competition for cavities with other cavity-nesting bird species. I am identifying the species that excavate and utilize the same types of nesting cavities as Bahama Swallows, and designing a cavity nest web illustrating the interactions of these species. (C) Predation: Increased abundance of nest predators could pose a threat to the Bahama Swallow. I am monitoring active nests to determine whether the rates of depredation are sufficiently high to contribute significantly to population declines.

Life history and ecology of the endangered Bahama Swallow (Tachycineta cyaneoviridis)

Authors: Maya Wilson 1 and Dr. Jeff Walters 1

Affiliations: 1. Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia

The Bahama Swallow (Tachycineta cyaneoviridis; BAHS) is an endangered species that is endemic to three islands in the northern Bahamas. Very little is known regarding the abundance, distribution or dispersal among islands of BAHS, or the factors responsible for the species’ decline. We are assessing the current population biology of BAHS using population surveys and genetic-based methods, and expanding the limited life history data available by locating and monitoring BAHS nests. Preliminary results show that BAHS breed between April and July, laying an average of three eggs in pre-existing cavities, primarily abandoned woodpecker cavities in snags of Caribbean Pine (Pinus caribaea) and utility poles, and holes in cell phone towers and buildings. Bahamian pine forests were heavily logged through the early 1970s; work to date suggests availability of nest sites limits populations, and reductions in this resource may be responsible for the species’ decline. We are conducting surveys of the pine forest and other habitats to assess the availability of cavity-nesting resources across the landscape and constructing a cavity-nest web illustrating species interactions. BAHS appear to rely on West Indian Woodpeckers (Melanerpes superciliaris) and especially Hairy Woodpeckers (Picoides villosus) to excavate cavities, and compete with secondary cavity-nesters including the American Kestrel (Falco sparverius), La Sagra’s Flycatcher (Myiarchus sagrae), House Sparrow (Passer domesticus) and European Starling (Sturnus vulgaris). By working with local organizations to facilitate and promote this work, our ultimate goal is to provide information that can be used develop conservation strategies for BAHS and their breeding habitat.