The GSS and Picnic event on March 24, 2023 is presented by the Biology Graduate Student Association and the Departments of Applied Ecology and Biological Sciences.
Below are the short talk abstracts:
CONNECTING URBANIZATION TO POPULATION DYNAMICS: MOVEMENT, RESOURCE SELECTION AND MORTALITY RISK OF WHITE-TAILED DEER ACROSS AN URBANIZATION GRADIENT
Mikiah Carver-McGinn1, Christopher Moorman2, Nils Peterson2, John Kilgo3, Elizabeth Kierepka4, Moriah Boggess5, Heather Evans5, Jonathan Shaw5, Nathan J. Hostetter6
1North Carolina Cooperative Fish and Wildlife Research Unit, Department of Applied Ecology, North Carolina State University
2 Fisheries, Wildlife, and Conservation Biology Program, North Carolina State University
3 USDA Forest Service Southern Research Station
4 NC Museum of Natural Sciences, Department of Forestry and Environmental Resources, North Carolina State University
5 North Carolina Wildlife Resources Commission
6 U.S. Geological Survey, North Carolina Cooperative Fish and Wildlife Research Unit, Department of Applied Ecology, North Carolina State University
Urbanization alters landscapes and the associated resources available for wildlife. These changes can drive new selection pressures, as individuals adapt to increased fragmentation and seasonal resources that differ from their historical environments. White-tailed deer (Odocoileus virginianus) are an important species to study in urbanizing landscapes because they are an adaptive generalist species that regularly interacts with human altered landscapes. We are conducting a three-year telemetry study to investigate white-tailed deer ecology across an urban-rural continuum in Durham and Orange counties in North Carolina. Our study applies a multi-scale approach to better understand how urbanization affects deer movements, resource selection, and mortality risk across these landscapes. Specifically, we are capturing male and female deer across a gradient from rural forest and farmlands to densely populated suburban areas to investigate: 1) deer movement relative to anthropogenic features and human activity, 2) seasonal home range size and how urbanization shapes landscape-level selection, and 3) deer survival and cause-specific mortality along the urban-rural continuum. Linking deer movement, selection of home range areas, and ultimately variation in mortality risks across these landscapes will provide science-based information to better understand deer ecology in urbanized areas and inform management of deer populations in North Carolina and beyond.
URBAN IMPACTS ON STREAM WATER TEMPERATURE AND CHIRONOMID LARVAL DEVELOPMENT IN A TROPICAL WATERSHED, PUERTO RICO
Vamery González-Hernández*1, Jesús Gómez2 and Alonso Ramírez1
North Carolina State University1, University of Puerto Rico Rio Piedras2
Urbanization is a major stressor on ecosystems and organisms, mainly through changes in temperature. Water temperature is a key environmental factor, along with food resources, in determining the development of aquatic insects. Our objectives were to assess how urban water temperatures are affecting the development of organisms, using Chironomus sp. as a model organism. Our study system was the Rio Piedras watershed, a highly urbanized system in the San Juan Metropolitan Area, Puerto Rico. We collected temperature data from 6 tributaries within the urbanized watershed creating a gradient from most to least urbanized and a non-urban stream as a reference. Temperature was measured every hour using HOBO sensors, one sensor placed in the water and one outside, under riparian vegetation. To assess water temperature effects on development, we set up four treatments: 22°C, 25°C, 30°C and a fluctuating temperature between 24°C and 30°C. We placed the organisms under the treatments, starting with egg masses and allowing them to complete their life cycle up to emergence. We measured egg hatching efficiency, larval size, and time of adult emergence. Our non-urban stream had a maximum water temperature of 23°C and daily diel cycle of 2 degrees. The most urbanized stream reached 30°C and had a daily diel cycle of 6 degrees. We found water and air temperatures significantly related with the level of urbanization in the subwatershed. Water temperature had no effect on egg mass hatching efficiency. In contrast, the number of days to reach instar IV, pupae, and adult emergence decreased as temperature increased. Time to reach instar IV decreased by 44%, pupae 58% and adult emergence 59% in the highest temperature. The treatment with the highest survival to adulthood was the fluctuating temperature treatment. Urbanization significantly increases water temperature in urban streams in Puerto Rico, affecting aquatic insect development.
HOW MEDIAN-HOUSEHOLD INCOME AFFECTS URBAN BEE HABITAT AND DIVERSITY
Cities often act as a refuge for native bee diversity. In an increasingly urbanized world amid mass pollinator declines, it is vital to understand how urban habitat supports bee diversity as well as how human intervention and socioeconomic factors play a role in structuring habitat in urban systems. Many studies have established a connection between high socioeconomic status and high biodiversity levels in plants, but few studies have shown if this trend holds true for native bees in cities, or how socioeconomic status influences native bee nesting and foraging habitat. In this study, we investigated how median-household income affects bee and plant diversity, as well as the presence of viable nesting habitat in the form of bare soil, across 30 residential sites in Raleigh, NC. Plant diversity was negatively associated with income (p = 0.016, β = -0.34) while it was positively associated with bee diversity (p = 0.062, β = 0.29). Meanwhile, bare soil was not significantly associated with bee diversity (p = 0.692, β = 0.44). Overall, there was no significant relationship between income and bee diversity (p = 0.946, β = 0.01). These results suggest that while bee foraging and nesting habitat varies with bee diversity and income, urban bee populations do not follow the luxury effect rule. Understanding the mechanism behind urban bee diversity can help us provide more beneficial bee habitat in cities in the future.
URBANIZATION SHIFTS ECOLOGICAL FUNCTION OF TEMPERATE CANOPY INSECTS
Michelle Kirchner, Lucie Ciccone, Clyde Sorenson, Elsa Youngsteadt
Forest canopies are teeming with life and house a diverse and abundant group of arboreal arthropods, who play key roles in forest nutrient cycles and community assembly. Due to high carbon:nitrogen ratios in the canopy, arboreal animals tend to increase their foraging efforts for nitrogen-based foods, while the opposite is true on the ground, implying that these communities contribute differently to the forest food web. Most knowledge about arboreal insects comes from hyper-diverse tropical forests, and insects in temperate forest canopies have received relatively little attention, particularly in North America, where eastern temperate forests are undergoing rapid urbanization. Here, we use ants as a study system to investigate how temperate insect nutritional ecology differs in urban and forest tree canopies. Ants are the dominant arboreal arthropod in many forest canopies, and they are frequently used in urban studies as ecological indicators. We employ a novel baiting method to test the impact of urbanization on arboreal ant nutritional preference across seven forest and seven urban sites in the Piedmont region of North Carolina, USA. We find that ants in temperate forest canopies do not show significant nutrient preference, counter to studies in tropical forest systems. However, in urban canopies, ants prefer protein over carbohydrates, as they do in the tropics. Our results show that temperate and tropical canopy ants contribute differently to forest food webs, suggesting that we cannot rely on results from tropical forests to understand temperate forest canopy ecology. Moreover, urbanization of temperate forests alters the ecological function of the canopy community; future work will assess whether the functional change is driven by shifts in ant community composition or behavior.
SEX BIAS AND OMISSION IN NEUROSCIENCE LITERATURE
Alice Liu1, John Meitzen2,3,4
- Graduate Program in Biology, NC State University, Raleigh, NC, USA
- Department of Biological Sciences, NC State University, Raleigh, NC, USA
- Center for Human Health and the Environment, NC State University, Raleigh, NC, USA
- Comparative Medicine Institute, NC State University, Raleigh, NC, USA
Despite known sex differences in the brain, behavior, and neurological disorders, neuroscience preclinical research has historically exhibited a sex bias, where male research subjects are favored more than female subjects. Neuroscience research has also historically demonstrated sex omission, the lack of sex reporting. To help address this issue, funding agencies as well as research journals have implemented informational campaigns as well as new policies requiring investigators either to consider sex as a biological variable or to report sex as part of comprehensive methods documentation. Our laboratory and others have extensively tracked the prevalence of sex bias and omission in neuroscience research literature, however the most recent data dates from 2017. To address this lack of data, here we analyzed sex bias and omission in neuroscience research articles published in 2020 from Nature, Science, Nature Neuroscience, Neuron, the Journal of Neuroscience and the Journal of Neuroscience. Regarding sex omission, 15% of articles did not report sex. Regarding sex bias, 23% of total analyzed articles reported using only males while only 5% of articles used only females. 47% of articles used both males and females but did not assess sex as a biological variable. 9% of articles used both males and females and assessed sex as a biological variable. These findings indicate that sex bias and omission persist in the neuroscience literature, despite new policies encouraging the consideration and reporting of sex.
EFFECTS OF WATER CHEMISTRY ON MACROINVERTEBRATES IN TROPICAL STREAMS DRAINING A VOLCANIC LANDSCAPE
Ana M. Meza-Salazar1 & Alonso Ramírez1
1Department of Applied Ecology, North Carolina State University.
Stream water chemistry may have distinctive characteristics in volcanic landscapes, such as high nutrient content. In volcanically active regions of Central America, some streams receive geothermal groundwater inputs with high solute concentrations (e.g., P, Cl, Mg, Ca). In contrast, other streams have mainly local groundwater inputs and are solute-poor. Our goal was to evaluate the effects of water chemistry on aquatic macroinvertebrate assemblages in streams with different geothermal groundwater inputs. We focused on a solute-rich stream and a solute-poor stream in northeastern Costa Rica and we measured the physicochemical variables of the water in each one. We set up five plastic boxes with rocks and leaves in each stream to standardize the substrate used. Samples were collected monthly, and organisms were identified to the lowest taxonomic level possible. Water conductivity and phosphorus concentrations were higher in the solute-rich stream, while pH fluctuated more in the solute-poor stream, with values between 3.8 and 6.5. Although richness was similar between the two streams, there were significant differences in the composition and structure of the macroinvertebrate assemblages of both streams (PERMANOVA, p-value>0.05). These differences were mainly determined by the greater abundance of taxa such as Chironominae and Tanypodinae (Diptera) in the solute-poor stream and of Ulmeritoides and Caenis (Ephemeroptera) and Polycentropus and Macronema (Trichoptera) in the solute-rich stream. We found that the input of geothermal waters affects the water chemistry. Macroinvertebrates respond positively to increased phosphorus concentrations in streams through higher-quality food resources and negatively to pH fluctuations that can cause acidification events.
BIOMARKERS OF HEALTH AND IMMUNOCOMPETENCE IN FRESHWATER MUSSELS: AN ASSESSMENT OF APPLICABILITY TO WILD AND HATCHERY POPULATIONS.
Madison E. Polera1, W. Gregory Cope1, Erin McKenney1, Catherine E. LePrevost1, Jeffrey A. Yoder2,Tal Ben-Horin3, Chris B. Eads1, Heather Evans4, Rachael Hoch4, J. Michael Fisk II4, Michael J. Walter4.
1Department of Applied Ecology, NC State University, Raleigh, NC. 2Department of Molecular Biomedical Sciences, NC State University, Raleigh, NC. 3Department of Clinical Sciences, NC State University, Raleigh, NC. 4NC Wildlife Resources Commission, Raleigh, NC.
Freshwater mussels (Order Unionida) are among the most imperiled faunal groups, facing enigmatic die-offs and widespread population declines. Historically, these declines have occurred following conspicuous impacts of habitat destruction, pollution, invasive species, and stream impoundments. Contemporary mussel die-offs often lack such discriminant explanations and diagnoses are often limited to post-hoc mass mortality evaluations. Sublethal metrics and markers serve to proactively identify infection, stress responses, and deviation from physiological homeostasis. We intend to identify, evaluate, and validate a suite of biomarkers reflective of immunocompetence and immunopathology by integrating immunology, microbiology, histopathology, and metabolomics. Samples of wild and hatchery mussels will be used to establish biomarker baseline reference ranges and describe variation across spatial and taxonomic scales. Experimental trials will be used to quantify the response of immune defense parameters in circulating hemolymph such as total and differential hemocyte counts, hemocyte morphology, and hemocyte function in the face of environmental stressors and infectious disease. The correlation between microbiome diversity metrics and mussel immune status will be evaluated in hemolymph and mucosal surfaces. Finally, metabolomics will be used to explore disease mechanisms and identify candidate hemolymph metabolite biomarkers. These assays will combat challenges of conducting health assessments on threatened and endangered species in streamside surveys by evaluating potential surrogate species and cross-validating mobile, accessible, noninvasive, and high throughput methods. We anticipate that these standardized practices of surveying for early warning signs of compromised health or susceptibility will better inform management, propagation, and conservation decisions.
ROLE OF POOL GEOMORPHOLOGY AND ROCK TRAITS ON TROPICAL STREAM INSECT OVIPOSITION PATTERNS OF PUERTO RICO
Mariely Vega Gómez1, Alonso Ramírez1
1Department of Applied Ecology, North Carolina State University, Raleigh, N.C., U.S.
Oviposition by aquatic insects is a process that is important for population and assemblage dynamics. For the Caribbean region, climate change projections indicate that geomorphology-altering disturbances are expected to become more intense or frequent. Our objective was to understand the role that geomorphological variables and rock traits play in oviposition patterns on small montane streams at El Yunque National Forest, Puerto Rico. We expected to find 1) a greater number of egg masses on exposed rocks given the greater visible area for females to land and reduced drowning or predation risks. We also expected to find a greater number of egg masses in smaller pools because they were shallower representing a lower predation risk. We placed 28 boulder-sized rocks (about the size of a fist) along six small and large pools in sections where the rocks would be either submerged or exposed. We monitored the abundance, morphotype, and location of egg masses for four weeks. During the mid-point, the rocks were relocated within each pool into opposite water level conditions. We recorded rock traits such as color, texture, visible area, and depth in the pools. We found that oviposition seems to occur on specific rocks, as over half the rocks with masses before the switch also had masses after relocation. However, none of the characteristics examined here explained patterns in the abundance of masses, their morphotypes, or their location on the substrates. We found that rock placement in pools, but not pool size, had a significant effect on the cumulative abundance of masses. Under the threat of a projected increase in disturbance frequency and intensity in the Caribbean, it is important to assess how the structure of the aquatic biota might change as a response to events that alter the geomorphology and substrate composition of stream environments.
PHYSIOLOGICAL AND LIFE HISTORY RESPONSES IN A MAYFLY (Callibaetis floridanus) INHABITING PONDS WITH SALTWATER INTRUSION.
Jamie K. Cochran1, David H. Funk2, and David B. Buchwalter1*
1Department of Biological Sciences, North Carolina State University, Raleigh, NC, 27695
2Stroud Water Research Center, Avondale, Pennsylvania 19311
Anthropogenic alterations to freshwater salinity regimes include sea level rise and subsequent intrusion of saline waters to inland habitats. While mayflies are generalized to be sensitive to increasing salinity, we know little about the physiological processes (and their plasticity) that determine the performance of species in a changing world. Here, we explored life-history outcomes and physiological plasticity in a population of mayfly (Callibaetis floridanus) from a coastal pond that routinely experiences saltwater intrusion. We reared naiads to adulthood across a gradient of increasing salinities (113, 5,020, 9,921 µS/cm). Radiotracer flux studies (22Na, 35SO4, and 45Ca) were conducted in naiads reared at each salinity, revealing a positive association between ionic concentration and uptake rates. However, the influence of rearing history on ionic influx rates was apparent when naiads were transferred from their respective rearing water to other experimental conditions. For example, we observed that naiads reared in the low salinity treatment (113 µS/cm) had 10.8-fold higher Na uptake rates than naiads reared at 9,921µS/cm and transferred to 113 µS/cm. Additionally, naiads acclimated to the higher salinity exhibited reduced uptake in ion-rich water relative to those reared in more dilute conditions (e.g., in 9,921 µS/cm water, 113 and 5,020µS/cm acclimated naiads had 1.5- and 1.1-fold higher Na uptake rates than 9,921µS/cm acclimated naiads, respectively). We found no significant changes in survival (80±4.4%, mean±s.e.m.) or naiad development time (24±0.3 days, mean±s.e.m.) across these treatments but observed a 27% decrease in subimago female body weight in the most dilute condition. This reduction in female weight was associated with higher oxygen consumption rates in naiads relative to the other rearing conditions. Collectively, these data suggests that saline adapted C. floridanus may be more energetically challenged in dilute conditions, which differs from previous observations in other mayfly species.
PRAIRIE RAMBLINGS: A NATURAL HISTORY OF THE PIEDMONT’S IMPERILED GRASSLANDS
The Piedmont prairie is a plant community which once stretched across the southeastern US in a patchwork of grassland savannas. Today “natural” areas in the Triangle are dominated by second growth forests with dense canopies, but historically a diverse understory of herbaceous plants similar in composition to the tallgrass prairies of the Midwest thrived in high-light environments across the region. Natural fires and those set by the indigenous peoples of the Piedmont suppressed tree growth and maintained the prairie. Grazing by large herbivores such as Bison bison and soils which frequently dried out and cracked may have further deterred the establishment of trees. European colonization, agriculture and urbanization have restricted prairie species to artificially-cleared habitats such as powerline cuts and roadside shoulders, particularly on regionally-rare soil types which are not suitable for cultivation. Rare and endangered plant species (such as the federally-listed Echinacea laevigata and recently-described Marshallia legrandii) persist in these habitats, but they are threatened by herbicide spraying and other civil maintenance practices. In this talk I will discuss the botanical, geological and anthropogenic history of this imperiled plant community. I will briefly review ongoing efforts by researchers in the southeast to conserve and restore the Piedmont prairie, and describe my own research into prairie plant reproduction and establishment at the community, trait and species levels.
THE ROLE OF HOST SWITCHING IN DISEASE TRANSMISSION POTENTIAL: IMPLICATIONS FOR POLLINATOR HEALTH
Bianca M. Jimenez, Rebecca Irwin
While some host-parasite systems can be characterized by a parasite infecting a single host species, in others, a parasite can spread disease across taxonomic groups via a complicated web of species interactions. The ecological processes driving pathogen spillover from principal hosts to alternatives and its implications are well characterized in some systems. However, the ecological determinants underlying parasite spillback have been less well characterized. Understanding pathogen spillback in webs of host-species interactions are critically important for understanding disease spread. The fecal-orally transmitted parasite Crithidia bombi infects the principal bumble bee host and also actively replicates in a series of alternative hosts. However, it remains unknown if and how much these alternative hosts spread Crithidia back to the principal host. Here we are using a mechanistic approach to assess how three basic steps of parasite transmission (deposition of infected feces on flowers, survival of parasites on flowers, and acquisition by the principal host) affect the likelihood of parasite spillback from alternative hosts to principal hosts. We are using the principal host Bombus impatiens and four alternative bee species that support Crithidia replication via shared flower use. The bees vary in size and we predict only the largest bees can spillback parasites to the host. Preliminary data conducted on B. impatiens suggest that bee size and fecal droplet volume are directly proportional such that larger bees produce larger fecal droplets. However, larger fecal droplets, associated with bigger B. impatiens, have fewer pathogen cells per uL. Experiments with the alternative hosts and transmission steps are on-going. If alternative hosts are able to drive parasite transmission potential back to the principal host, they could be important in creating disease epidemics in webs of plant-pollinator interactions, with implications for pollination services.
EVOLUTION OF PUPILLARY RESPONSES IN ORGANISMS ‘WITHOUT’ PUPILLARY RESPONSES
Parker Hughes, Dr. R. Brian Langerhans
The eyes of many vertebrates contain mobile pupils that constrict and dilate in response to different stimuli, such as ambient light levels. This change in size is used to adjust how much light enters the eye, and can respond to different light conditions to increase visual acuity and sensitivity (Douglas, 2018). The most species-rich group of vertebrates, teleost fish, surprisingly appear to lack this ability, having immobile pupils (with a few exceptions). For many fish, perhaps selection has seldom favored pupillary responses owing to infrequent or inconsequential cases of rapid changes in luminance. However, in some visually-oriented fishes, activities such as detecting and avoiding predators, interacting and mating with conspecifics, and foraging occur under highly variable light conditions (including nighttime). Here we tested for pupillary responses in Bahamas mosquitofish (Gambusia hubbsi) within the context of a post-Pleistocene adaptive radiation. We uncovered strong pupillary responses to ecologically relevant light conditions over short times scales (seconds to minutes). Using a common-garden experiment, we are further testing hypothesized drivers for evolutionary changes in this ability, including predation risk, resource competition, nighttime foraging, and water transparency.
COMPOSITION AND EFFECTS OF MULTIPLE SERUM TYPES ON FRESHWATER MUSSEL DEVELOPMENT DURING IN VITRO PROPAGATION
Loretta M. Lutackas, Chris B. Eads, W. Gregory Cope
Captive propagation of freshwater mussels (order Unionida) is a tool used in conservation to augment populations that are declining in the wild. Through in vitro techniques that mimic the unique parasitic life phase possessed by this globally endangered animal group, we are able to propagate many species without the use of live host fish (in vivo propagation), thereby reducing costs, time, and potential impact on fish populations. Using modified cell culture techniques, larval mussels (called glochidia) are placed in a combination of cell culture media, mammalian serum (a readily available protein source), and antimicrobials until the metamorphosis to the juvenile life stage is complete. Suboptimal in vitro conditions, however, can negatively impact transformation rate, juvenile development, and consequently, juvenile performance post-transformation. We have observed differences in juvenile activity levels and foot and organ development based on different media serum types. In this study, we will characterize the amino acid and lipid composition of three common sera (equine, fetal bovine, and rabbit) used for in vitro propagation of freshwater mussels and use various combinations of them to propagate two North Carolina native mussel species: Elliptio lanceolata and Venustaconcha constricta. Pre-transformation development will be documented and categorized; metabolomics will be used to understand the biological processes occurring and those associated with the growth observed at a given time point. To further examine juvenile performance, survival and growth will be measured for one month. This study will fill an existing knowledge gap for larval development and its association with serum composition. It will aid in identifying critical components for suitable serum selection for these species and link visual developmental markers indicative of a successful transformation with metabolomic data. In the future, these data can be compared to host fish blood composition for further insight into integral elements required for early growth.
ASSESSING THE ACUTE TOXICITY OF MANGANESE TO FRESHWATER MUSSELS
Clayton Lynch*1, W. Gregory Cope1, Monte McGregor2
1Department of Applied Ecology, North Carolina State University, Raleigh, NC
2Center for Mollusk Conservation, Kentucky Department of Fish & Wildlife Resources,
North American freshwater mussels of the family Unionidae are experiencing high imperilment status due to multiple human mediated changes. Adverse impacts from unknown origins have caused mussel die-offs, population declines, and decreased mussel growth and survival. Investigations have uncovered an unexplained relationship between high Manganese (Mn) concentrations and these events. To understand the effects of Mn on mussel survivability, we conducted a series of acute toxicity tests on the early life stages of multiple species from the family Unionidae. Acute tests were run on the glochidia of 9 species and on the juveniles of 5 species. Glochidia and juveniles of each species were exposed to seven concentrations of Mn from 5 to 160mg/L following ASTM protocols. Glochidia underwent a 48-hour acute toxicity test, where viability was assessed at hour 24 and 48. Juveniles underwent a 96-hour acute toxicity test, where viability was assessed at hour 48 and 96. We calculated the median lethal concentration (LC50) for each of the acute toxicity tests. The LC50 for the glochidia stage at 24 h using MnCl2 ranged from 16.8 mg/L to 115.6 mg/L. The LC50 for the glochidia stage at 24 h using MnSO4 ranged from 18.1 mg/L to 125.2 mg/L. Epioblasma triquetra was the most sensitive to both forms of Mn. At the 96h time point, the juvenile LC50s ranged from 22.8 mg/L to 160 mg/L after MnCl2 exposure and 18.9 mg/L to 143.7 mg/L after MnSO4 exposure. Utterbackia imbecillis was most sensitive to MnCl2 and Lampsilis cardium was most sensitive to MnSO4. Acute exposure to dissolved Mn in two common forms can negatively impact freshwater mussel viability, especially at the glochidia stage. This research can be used to establish freshwater mussel conservation plans and identify stream areas at risk to mussels.
STATUS ASSESSMENT OF HENSLOW’S SPARROW (CENTRONYX HENSLOWII) IN NORTH CAROLINA: FOUNDATIONAL DATA TO GUIDE STRATEGIC MANAGEMENT OF THE SPECIES AND ENHANCE STATEWIDE PERSISTENCE
1Department of Applied Ecology, North Carolina State University, Raleigh, NC
The Henslow’s Sparrow (Centronyx henslowii) is a conservation priority in North Carolina due to its limited presence within the state and declining populations throughout the rest of its range. I am addressing four research objectives to evaluate Henslow’s Sparrow redundancy, representativeness, and resiliency in North Carolina, which will lay the foundation for developing a species status assessment and management plan for the Henslow’s Sparrow within the state. In this presentation I’ll share an overview of our research goals and highlights after two field seasons of studying the Henslow’s Sparrow at the Voice of America Game Land.
PARASITES AS TOOLS FOR SNAKE CONSERVATION
Alexandria P. Nelson and Skylar R. Hopkins
While abundant throughout North Carolina, snakes are notoriously cryptic and difficult to study. In fact, we know little to nothing about the parasite communities in 23 out of our 38 native snake species. Quantifying snake parasite diversity will allow us to better understand snake ecology, identify potential snake-parasite coextinction events, and further snake conservation; all of which are timely concerns associated with global change. Therefore, for my dissertation, I aim to describe parasite infracommunity populations in snakes and to resolve the life cycles of the parasite species that infect them. I also hope to identify parasite species that can serve as bioindicators of snake presence within an ecosystem. Trematode parasites, for example, have the potential to serve as snake indicators. Trematodes infect two to three hosts throughout their life cycle. They typically have a snail first intermediate host, and they tend to be species-specific in their final hosts, like snakes. Thus, if we sample common snails and we find the larval stage of a parasite that we know to infect water snake final hosts, then we can infer that water snakes must be present in that environment, without ever having to sample them. I will identify potential bioindicator species through a combination of freshwater snail dissections, roadkill snake dissections, and parasite DNA sequencing. With genetic analyses, I will connect larval trematode stages in snails to the adult stage in snakes, and likely uncover the presence of new or cryptic trematode species for the first time. This work may be used by future wildlife managers to assess the health and presence of threatened snake species that are in need of conservation.
ESTABLISHING A STANDARDIZED SINGLE-NUCLEOTIDE POLYMORPHISM (SNP) PANEL FOR GENETIC PARENTAGE-BASED TAGGING (PBT) OF THE TAR RIVER SPINYMUSSEL (PARVASPINA STEINSTANSANA) AND YELLOW LANCE (ELLIPTIO LANCEOLATA)
Edie Nissen1, Heather Evans2, W. Gregory Cope1
1Department of Applied Ecology, North Carolina State University, Raleigh, NC
2North Carolina Wildlife Resource Commission, Raleigh, NC
Freshwater mussels are among the most imperiled groups of organisms around the world, and North America harbors more than 300 species. Because of the important role these animals play in nutrient cycling and other ecosystem services, they can have a substantial impact on the health of aquatic habitats. Due to pollution, habitat loss, and declining water quality, around 75% of our 300 species are threatened, endangered, of special concern, or are already extinct. Two imperiled species distributed in Central North Carolina are the federally endangered Tar River Spinymussel (Parvaspina steinstansana), and the state endangered Yellow Lance (Elliptio lanceolata). The objective of this study is to create a standardized single-nucleotide polymorphism (SNP) panel for these two species to be used in monitoring the success of hatchery stockings through genetic parentage based tagging (PBT). DNA samples have been collected from Tar River Spinymussel and Yellow Lance broodstock. Positive controls for each species have been obtained, as well as any negative controls (wild-born not used as broodstock) that could be found. A selection of several hundred SNPs will be pulled from thousands of previously identified SNPs to create a panel that will allow for high throughput, yet accurate detection of hatchery-bred individuals. Ultimately, the panel will be used to monitor genetic diversity and population structure with ongoing restoration efforts. This study will contribute knowledge and resources for future reintroductions and augmentations of these imperiled mussel species, as well as provide insight on the benefits of using genetic tools in conservation.
DESCRIBING THE MACROPARASITE COMMUNITIES OF SNAKES ACROSS NORTH AMERICA: A SYSTEMATIC LITERATURE REVIEW
Parasites are ubiquitous and act as important species in ecosystems. They regulate host populations, mediate interactions in host communities, and influence energy flow in food webs. Yet most parasite species remain undiscovered and undescribed, and most described parasites have not been studied with regards to their life histories and ecologies. The parasites of reptile hosts are especially poorly studied among vertebrate hosts, lacking broadscale databases and biogeographical analyses of the processes that drive their diversity and distributions. We conducted a systematic literature review of macroparasites that infect snakes using existing bibliographies for North America and additional database searches. We recorded information regarding snake hosts (e.g., species, size), parasites (e.g., species, prevalence of infection), and habitats (e.g., region, habitat type). We found that half of the snake species in the United States and Canada have never been examined for macroparasites. We also found that parasite species richness follows patterns of snake species richness, as expected. For example, the Southeastern and Southwestern U.S. are home to more snake species, and correspondingly, have more parasite species recorded from snake hosts. Our novel snake–parasite database includes over 160 unique endoparasite species, of which a majority are adults suggesting many larval parasites may be unrecorded. Furthermore, trematodes, nematodes, and cestodes were the most reported parasite taxa in the snakes sampled, whereas acanthocephalans and pentastomids were the least reported parasite taxa. These results suggest that specific parasite species, and especially trophically transmitted parasites like trematodes, may yield critical insights into the diets and trophic relationships of cryptic and difficult-to-study snake hosts.