Ecology and Evolutionary Biology Commons^™

Explicit Probability Of Fixation Formula For Mutual Competitors In A Stochastic Population Model Under Competitive Trade-Offs, Glenn Steven Young, Andrew Belmonte

Biology and Medicine Through Mathematics Conference

No abstract provided.

The Role Of Variation In Mate Choice And Wolbachia Infection On Aedes Aegypti Population Dynamics, Bernardo Ameneyro

Biology and Medicine Through Mathematics Conference

No abstract provided.

Belowground Characteristics Of Dominant Coastal Dune Grasses And Potential Community-Level Effects On Coastal Erosion, Shannon L. Walker

Theses and Dissertations

Natural dunes arise out of complex relationships between ecological, hydrological, and geological processes and are important for reducing erosion along coastlines. Aboveground structures of coastal dune grasses are known to impact erosional dynamics, and recent studies have shown that belowground structures—such as roots, rhizomes, and belowground stems— may be important in erosional resistance. My objectives were to 1) characterize above- and belowground characteristics of prominent dune grasses and 2) combine these data with functional group abundances and distribution to evaluate community effects on two adjacent locations of distinctive morphology and erosional characteristics and their response to storm disturbance. Whole plant …

The Origin And Evolution Of Flower Characters In Angiosperms With A Case Study On The Genetic Basis Of Zygomorphic Corolla Development In Bee And Hummingbird Pollinated Species Of Schizanthus (Solanaceae), Ghadeer Bukhari

Theses and Dissertations

This Ph.D. dissertation investigates two main projects separated into two chapters, one for each. The first chapter explores the evolution of flowering plants (angiosperms), a macro-scale study. The second project is on a micro-scale that focus on exploring the genes that regulate the similarities and the differences of flower morphology reflecting their different pollination syndromes in two species of Schizanthus (Solanaceae), i.e., S. pinnatus, a bee-pollinated flower, and S. grahamii, a hummingbird- pollinated flower.

In the first chapter, I used floral diagrams to study the origin and the evolution of floral traits in angiosperms, a new set of morphological data …

The Heat Is On: Comparison Of Thermoregulatory Behavior In Parasitised Versus Unparasitized Caterpillars Of The Tobacco Hornworm, Manduca Sexta (L.) [Lepidoptera: Sphingidae], Jessica M. Johnston

Theses and Dissertations

Insect thermoregulatory research has demonstrated evidence of variation occurring within and among species with respect to infection, pathogens, and parasitism, but few studies have examined differences in thermoregulatory behavior in a host-parasite system with a coevolved symbiotic virus. I investigated the role of parasitism by Cotesia congregata (Say) (Hymenoptera: Braconidae) on the thermoregulatory behavior of Manduca sexta (L.) (Lepidoptera: Sphingidae) using an experimental design in a thermal gradient chamber and a complementary observational field study on wild M. sexta collected from tobacco farms. Parasitism and larval age were not found to have a significant effect on the preferred body temperature …

Plant-Pollinator Associations In An Eastern Serpentine Savannah And The Effects Of Overbrowsing, Allyson Richins

Theses and Dissertations

Chapter 1: Native plant response to deer overbrowsing in a serpentine savannah

Plants are particularly vulnerable to physical disturbance in low productivity areas, due to a high cost of replacing lost plant tissue. In the eastern United States, serpentine grasslands are fragmented ecosystems with high concentrations of rare endemic plant species, low concentrations of soil nutrients, and uncontrolled deer overpopulation. This study assessed functional responses of native angiosperms in a rare eastern serpentine savannah to selective deer browsing. Plant count, flower count, floral area, vegetative area, and plant height of 10 serpentine plant species were compared inside and outside of …

Taxa Specific Responses To Flooding Shape Patterns Of Abundance In A River Rock Pool Metacommunity, Charles R. Stunkle

Theses and Dissertations

Connectivity and habitat area are important landscape characteristics that drive patterns of abundance and diversity across scales. However, responses to connectivity and patch size are dependent on species traits. Riverine landscapes are highly dynamic both spatially and temporally with hydrologic connectivity being a major driver of abundance and diversity. Here we modeled densities of the Virginia river snail and skimmer dragonfly nymphys, two taxa with differences in their dispersal abilities and life histories, as a function of flooding, patch area, and season in over 300 riverine rock pools. We found key differences in how each taxon responded to these predictors …

Evidence Of Local Adaptation To Climate In An Invasive Ectotherm: A Study On The Eurasian Gypsy Moth (Lymantria Dispar) In North America, Phillip M. Gibbs

Theses and Dissertations

Invasive species exist in nearly every ecosystem both terrestrial and aquatic. Improving our understanding of the mechanisms that shape the ability of these organisms to physiologically cope with their surroundings will be crucial to preparing for future impacts of climate change. The Gypsy Moth (Lymantria dispar) has been expanding its range across North America over the last 100+ years since its arrival in Medford, Massachusetts. This study quantifies upper thermal limits (UTL) across 8 different populations of L. dispar in North America and seeks to determine if signals of local adaptation to climate across a latitudinal gradient may …

Assessing The Feasibility Of Freshwater Mussel Restoration In Urban Streams., John-Reid Ryan

Theses and Dissertations

Abstract

The main objective of this study was to determine whether introduced freshwater mussels (Alewife floater, Utterbackiana implicata) can survive and grow in urban streams in the James River watershed. A secondary objective was to assess differences in U. implicata survival and growth of in the context of differing water quality and food resource conditions among three urban sites and three rural sites. Results from this study show large differences in growth and survivorship of mussels across sites. Higher survivorship was observed among mussels stocked into rural streams (35% and 44%) in comparison to urban streams (3%, 6% and 14%). …

Bee Diversity Of Three Appalachian Shale Barren Sites, Olivia C. Latham

Theses and Dissertations

Insect pollination is vital to ecosystem function. However, climate change, habitat loss, pesticides, and a variety of other anthropogenic sources are contributing to a decline in pollinator diversity. Fragile small ecosystems with a high composition of specialized plant species that rely on specific pollinators such as Appalachian shale barrens, are especially at risk of losing biodiversity. This study combines the use of active sweep net sampling of endemic shale barren forbs and passive trap methods over the course of a bloom season (April-August) in three barren sites to identify bee community populations and visitation relationships between pollinator species and endemic …

Interspecific Gene Flow Potentiates Adaptive Evolution In A Hybrid Zone Formed Between Pinus Strobiformis And Pinus Flexilis, Mitra Menon

Theses and Dissertations

Species range margins are often characterised by high degrees of habitat fragmentation resulting in low genetic diversity and higher gene flow from populations at the core of the species range. Interspecific gene flow from a closely related species with abutting range margins can increase standing genetic diversity and generate novel allelic combinations thereby alleviating limits to adaptive evolution in range margin populations. Hybridization driven interspecific gene flow has played a key role in the demographic history of several conifer due to their life history characteristics such as weak crossability barriers and long generation times. Nevertheless, demonstrating whether introgression is adaptive …

The Influence Of Breeding Density On Female Aggression, Parental Care, And Ornamentation In A Secondary-Cavity Nesting Warbler, Elsa B. Chen

Theses and Dissertations

Tradeoffs between individual survival and reproductive success associated with aggressive behaviors are a driving force of evolution, but these tradeoffs are often overlooked for aggressive conspecific interactions between females. For avian males, it is well documented that more aggressive individuals tend to provide less parental care. In the few studies that address this in females, the tradeoffs seem to be more context-dependent, varying due to factors such as predation pressure and habitat quality. The relationship between female ornamentation and aggression is similarly understudied, but evidence suggests that both aggression and ornamentation are important traits involved in social selection – the …

Stimulated Growth Response To Sand Burial Of A Coastal Shrub, D. Nicole Keller

Theses and Dissertations

Drivers of vegetation zonation on barrier islands are complex and interconnected. Sand burial is a strong driver in dynamic coastal systems, especially in the foredune community. However, it is not well understood how burial impacts the interdunal swales communities and it is especially difficult to separate the effects of burial from salinity. Climate change is altering the frequency of overwash events as well as expanding the range of the native shrub, Morella cerifera, on the Virginia barrier islands. To accurately forecast island response to climate change it is important to understand how the shrub responds to sand burial. Juvenile …

Phylogenetic Inference Of Multiscale Selection Pressures Using A Continuous State Birth-Death Process, Marco Hamins-Puertolas, David Rasmussen

Biology and Medicine Through Mathematics Conference

No abstract provided.

Characterizing The Permanence And Stationary Distribution For A Family Of Malaria Stochastic Models, Divine Wanduku

Biology and Medicine Through Mathematics Conference

No abstract provided.

Effects Of Predator Diversity On Optimal Communities For Prey Suppression, Amanda N. Laubmeier

Biology and Medicine Through Mathematics Conference

No abstract provided.

Upper Thermal Limits Vary Among And Within Native Bee Species In Relation To Season, Voltinism, And Nest Type, Kálmán K. Csigi Xiv

Theses and Dissertations

Native bees are only recently gaining attention for the extent to which they aid in pollination and ecosystem services. These services are threatened by predictions of warming temperatures if bees are not able to respond. Voltinism - the number of generations produced annually- can strongly influence thermal conditions experienced by both developing and adult bees based on emergence strategies for each voltinism type. Differences in experienced thermal conditions brought on by climate change could therefore affect upper thermal limits (UTL) in bees. This study observes UTLs across a foraging season within and among native bee species vi to elucidate the …

Nutrient Uptake Among Urban And Non-Urban Streams Within The Piedmont Physiographic Province Of Virginia, Joseph T. Famularo

Theses and Dissertations

To assess how urbanization impacts stream nutrient uptake, a series of instantaneous (i.e. slug) nutrient additions were conducted in 3 urban and 3 non-urban streams during open and closed canopy conditions. Single additions of N, P, and combined additions of N and P were performed at each site. These data were used to test the hypothesis that high N:P concentrations in urban streams would result in P-limited conditions, and to assess differences in nutrient uptake kinetics (i.e., the relationship between uptake and concentration) between urban and non-urban streams. The results show that there were no consistent differences in N vs. …

Assessment Of Microbial Carbon Processing And Its Implications To The Carbon Budget Of Lake Superior, Lindsey Michelle Koren

Theses and Dissertations

Over the past few decades, there has been increased research focus on carbon cycling within aquatic systems, especially with the changing global climate. Inland waters play a major role in the global carbon cycle, but the fundamental features remain poorly understood, particularly the large lakes of the world. Our experimental approach assessing the carbon budget of Lake Superior, the largest freshwater lake by area, provides spatial and temporal variability that has been previously overlooked but may be critical to our understanding on the biogeochemical processes controlling the lake. Multiple stations were chosen across the lake, both nearshore and offshore, to …

Spatial Genetic Structure And Local Adaptation Within And Among Foxtail Pine (Pinus Balfouriana Subsp. Balfouriana) Populations Located In The Klamath Mountains, California, Rebecca D. Piri

Theses and Dissertations

Foxtail pine (Pinus balfouriana) is a subalpine conifer endemic to California, notably separated into two disjunct subspecies. Previous studies have described the northern subspecies,Pinus balfouriana subsp. balfouriana,as having an uncommonly high level of genetic differentiation and no discernible spatial patterns in phenotypic variation. This study seeks to characterize the spatial genetic structure and patterns of selection of the northern subspecies (Pinus balfouriana subsp. balfouriana) using genome-wide data and to identify the influence of ecology and environment on the unique genetic patterns. I show that genetic differentiation among populations is much less than previously estimated …

Eternal Enemies, Or Incidental Encounters? Structure And Patterns Of Interspecific Killing In Carnivora, Tor G. Bertin

Theses and Dissertations

Lethal interactions between carnivorans (interspecific killing) may influence their population dynamics, behavior, and other important aspects of their ecology. In this study, I expand upon previous research on the broad-scale patterns of interspecific killing in Carnivora (Palomares & Caro 1999, Donadio & Buskirk 2006) with a greatly expanded dataset (inclusion of scat and stomach data and more intensive sampling of the literature), and suggest avenues for future research. While like previous studies, I found a positive effect of relative body size between killer species and killed species on the likelihood of forming a killing interaction, I failed to find evidence …

Spatial And Temporal Distributions Of Larval Clupeid Fishes In A Tidal Freshwater Marsh Complex, Philip Reid Anderson

Theses and Dissertations

Tidal freshwater wetlands provide valuable ecosystem services such as nutrient cycling, coastal flood control, and reproductive habitat for early life stages of economically and ecologically important fishes. The nutrient rich environments that tidal freshwater wetlands occur in support high levels of primary productivity of phytoplankton and vegetation that provide essential reproductive habitat for anadromous clupeid fishes (Alosa spp., Brevoortia tyrannus) in Chesapeake Bay tributaries. Seasonal retention of clupeid eggs and larvae within tidal freshwater habitats may enhance early growth, survival, and year class strength. The primary goal of the present study was to characterize the relative importance of …

Characterizing Water Quality And Hydrologic Properties Of Urban Streams In Central Virginia, Rikki Lucas

Theses and Dissertations

The objective of this study was to characterize water quality and hydrologic properties of urban streams in the Richmond metropolitan area. Water quality data were analyzed for six urban sites and two non-urban sites. Geomorphological surveys and conservative tracer studies were performed at four urban sites and one non-urban site to describe intra- and inter- site variability in transient storage, channel geomorphology, and related hydrologic parameters. Urban sites showed elevated concentrations of nitrogen and more variable TSS concentrations relative to reference sites. Urban channels were deeply incised with unstable banks and low sinuosity. Little Westham Creek exhibited the greatest transient …

Mechanisms Underlying Production Stability In Temperate Deciduous Forests, Shea B. Wales

Theses and Dissertations

A persistent and reliable future terrestrial carbon (C) sink will depend on how stable forest production is under more variable climate conditions. We examined how age, forest structure, and disturbance history relate to the interannual variability of above-ground wood net primary production (NPPw). Our site in northern Michigan spans two experimental forest chronosequences and three late successional stands; the chronosequences have distinct disturbance histories, originating following either clear cut harvesting (“Cut Only”) or clear cut harvesting and fire (“Cut and Burn”), and range from 21 to 108 years old. Annual NPPw was estimated using dendrochronology and site specific allometric equations. …

Geospatial Analysis Of Invasive Plant Species And Their Threats To Ecological Functionality At The Vcu Rice Rivers Center, Erik W. Kellogg

Theses and Dissertations

Invasive plants are a significant threat to native ecosystems and to biodiversity. They are often strong competitors and have multiple techniques to outcompete native plants. Thus, controlling or removing invasive plants facilitates the restoration of native ecosystems. We used GPS technology coupled with field surveying techniques adapted from the U.S. Fish and Wildlife Service to locate and identify invasive plants present within VCU’s Rice Rivers Center. We digitally overlaid a 50-meter x 50-meter grid system over the property. In each grid cell we recorded visual estimations of invasive plant coverage sorted into modified Daubenmire cover classes and used ArcGIS for …

Influence Of Environmental Features On Spermatophore Placement In Spotted Salamanders (Ambystoma Maculatum), Megan A. Kuechle

Theses and Dissertations

Successful reproduction in salamanders is driven by behavioral, environmental, and temporal interactions among adults. While much of our understanding of salamander mating systems is based upon either courtship behavior of both sexes or aspects of female choice, the decisions made by males regarding where to place spermatophores is much less quantified. In this study, we mapped male spermatophore placement in the spotted salamander (Ambystoma maculatum) with respect to ecological and spatial locations within a vernal pool complex in Charles City County, Virginia. The overall goal was to use the spatial and ecological placement of spermatophores to determine if …

Testing For Cryptic Diversity And Inference Of Population Structure In The Cosmopolitan Hoplonemertean Emplectonema Gracile (Nemertea), Paul L. Delaney Iv

Theses and Dissertations

Emplectonema gracile (Johnston 1837) is a hoplonemertean of marine intertidal hard-bottom communities and is distributed throughout the Northern Hemisphere. Although possessing a planktonic larval stage in its life history, the range of such cosmopolitan marine invertebrate species is often explained by cryptic speciation and anthropogenic transport. The purpose of this study is to test for possible cryptic species using mtDNA markers (COI and 16S rDNA) and to investigate population structure in E. gracile over a portion of its geographic range using mtDNA markers and ddRADseq nuclear SNP data. The results of both phylogenetic- and tree-based species delimitation revealed that E. …

Predicting Critical Transitions In Spatially Distributed Populations With Cubical Homology, Laura Storch, Sarah Day

Biology and Medicine Through Mathematics Conference

No abstract provided.

The Role Of Outcome Preferences In Optimizing Heterogenous Disease Control Strategies., Evan Milliken

Biology and Medicine Through Mathematics Conference

No abstract provided.

Modular Structure In Fish Co-Occurrence Networks: A Comparison Across Spatial Scales And Grouping Methodologies, Daniel Mcgarvey Dr., Joseph Veech

Environmental Studies Publications

Network modules are used for diverse purposes, ranging from delineation of biogeographical provinces to the study of biotic interactions. We assess spatial scaling effects on modular structure, using a multi-step process to compare fish co-occurrence networks at three nested scales. We first detect modules with simulated annealing and use spatial clustering tests (interspecific distances among species’ range centroids) to determine if modules consist of species with broadly overlapping ranges; strong spatial clustering may reflect environmental filtering, while absence of spatial clustering may reflect positive interspecific relationships (commensalism or mutualism). We then use non-hierarchical, multivariate cluster analysis as an alternative method …