Population Biology Commons^™

Managing Multi-Drug Resistance: An Evolutionary Game Theory And Optimal Control Approach, Shukhrat Nasrulloev

Theses and Dissertations

Multi-drug resistance is an evolutionary process in which treatment eliminates sensitive cells, allowing resistant clones to dominate. This thesis investigates this process using a framework integrating population dynamics, evolutionary game theory, and optimal control theory. We develop a two-population logistic growth model describing competition between drug-sensitive and drug-resistant cells under treatment, construct dose-dependent payoff matrices and replicator dynamics to characterize evolutionary competition, and derive a critical drug level D_crit = (r_S - rR)/(dS - d_R) at which resistant cells gain a fitness advantage. An optimal control problem is formulated via Pontryagin's Maximum Principle to identify schedules …

Diversification Of Avifauna In The Darién Highland Region: Ecological Niche Modeling, Phylogeography And Morphology To Explore Speciation In The Montane Species Myadestes Coloratus, Chlorospingus Tacarcunae And Margarornis Bellulus., Jorge L. Garzon Vasquez Mrs

Theses and Dissertations

Montane regions in the Neotropics are hotspots of endemism and biodiversity, yet their species are especially vulnerable to the impacts of climate change and geographic isolation. This thesis investigates the evolutionary and ecological dynamics of three bird species endemic to the Darién Highlands of eastern Panama: Myadestes coloratus, Chlorospingus tacarcunae, and Margarornis bellulus. Through an integrative approach combining ecological niche modeling, morphometric analysis, and genomic data from ultraconserved elements (UCEs) and mitochondrial DNA, the study explores the historical biogeography, current distribution patterns, population structure, and phenotypic differentiation of these montane taxa. Ecological niche models revealed that suitable habitat …

The Influence Of Wind Energy Development On Occupancy Of Medium And Large-Sized Mammals In South Texas, Elwynn Sherman

Theses and Dissertations

Conservation paradigms have shifted from single to multi-species approaches for assessing and conserving mammalian populations and the habitats that they occupy. The effect of wind turbine development is an important anthropogenic change to study due to the increasing demand for wind energy in Texas. In this study, I gathered remote camera trap data on medium and large-sized mammal populations in south Texas Tamaulipan thornscrub habitat. The objectives were to determine species presence, the effect of habitat characteristics and anthropogenic disturbances on species occupancy, and the effect of temperature on species detection. The results showed that distance from wind turbines did …

High Intraspecific Diversity Of Pocillopora Damicornis In Southeast Asia Reflects Adaptive Potential To Climate Change, Maria Lucille Carr

Theses and Dissertations

Marine heatwaves are increasing in intensity and frequency because of increased emissions of greenhouse gases. On coral reefs, warmer temperatures cause coral bleaching, mortality, and shifts in benthic composition. However, coral bleaching responses and survival vary geographically. Several hypotheses may explain such geographical differences in thermal tolerance, including the possibility that some localities may support higher intraspecific diversity than other localities, increasing the likelihood of survival of some individuals through heatwaves. Here we assessed geographic patterns of intraspecific genetic diversity in the ubiquitous coral Pocillopora damicornis. Intraspecific genetic diversity was assessed for 428 sequences across 44 sites in the Pacific …

Of Changing Climate And Habitat: Range-Wide Individual Growth And Local Patterns Of Phenology And Landscape Use In A Threatened Pit-Viper, James Helferich

Theses and Dissertations

Over the 21st century, climate change and wetland habitat loss will pose major threats to the Eastern Massasauga (Sistrurus catenatus), a federally threatened and Great Lakes region endemic rattlesnake. I collected capture-recapture data from sites across the range and modeled the effect of climatic variables on growth rate and asymptotic size. I found that high snow residence time was associated with larger asymptotic sizes but slower growth, while high spring precipitation increased growth rate. I then projected future growth and size under different carbon emission scenarios. Given the threat posed by successional encroachment of woody vegetation, I used spatially explicit …

Evaluation Of Nutrient Digestibility Of Weaned Calves From Early And Late Shedding Dams, Jennifer Keele

Theses and Dissertations

Researchers have investigated several factors that could alter fetal growth, including nutrient restriction (Valiente et al., 2021), hair shedding (Gray et al., 2011), and extreme hot and cold temperatures (Davidson et al., 2022). Hot temperatures and increased humidity percentages in the southeast United States caused researchers to investigate the hair coats of Angus cattle in the commercial production setting. An improvement in fiber digestibility and calf birth and weaning weights has been observed in Angus dams that shed 50% of the winter hair coat by May (Gray et al., 2011; Burnett et al., 2021). Our objective of this experiment was …

Population Demography Of A Neotropical Migratory Songbird In The Face Of A Changing Climate, Adele Balmer

Theses and Dissertations

This dissertation investigates the population dynamics and demographic trends of the Prothonotary Warbler (Protonotaria citrea), a migratory songbird that breeds in North America during the spring and summer and overwinters in Central and northern South America. The primary objective of this dissertation is to examine the combined implications of variation in weather and individual traits on demographic traits and to project the effects of climate change on population trajectories of the Prothonotary Warbler.

The analyses conducted in this dissertation centered around female Prothonotary Warblers; however, visual identification of a nestling’s sex is impossible in most altricial bird species, …

Evaluating Non-Invasive Environmental Methods For Detecting Tropical African Pangolin Species To Inform Conservation Actions, Ichu Godwill Ichu

Theses and Dissertations

Tropical African pangolin species are threatened throughout their range due to habitat loss and illegal take. Limited knowledge on distribution has rendered conservation efforts challenging. Methods commonly used for other wildlife species need to be tested for each pangolin species as each has variable ecologies requiring specific detection and monitoring techniques. This thesis evaluates the efficacy of two non-invasive environmental methods for detecting tropical African pangolin species, and consists of two complementary studies; a proof of concept study using soil sourced eDNA from a white-bellied pangolin enclosure in the Columbus Zoo, Ohio, to detect the species, and a field study …

Migration Ecology Of American White Pelicans: Circannual Movement, Geographic Range, And Annual Survival, Ryo Ogawa

Theses and Dissertations

Responses of migratory birds to seasonal climate and long-term environmental changes have been a central theme of avian migration ecology. Atmospheric conditions (e.g., winds and thermals), climate, and land cover and land use (LCLU) are major factors influencing the flights of soaring birds. Soaring American White Pelicans (Pelecanus erythrorhynchos) (hereafter, AWPEs) migrate between the subtropical Gulf of Mexico (GOM) and the temperate Northern Great Plains. American White Pelicans are also economically important piscivorous birds, causing enormous damages to the commercial Channel Catfish (Ictalurus punctatus) aquaculture in the Southeastern US. My studies aimed to evaluate the effects …

Evaluating Population Genetic Structure And Potential Genomic Signals Of Natural Selection In A Migratory Songbird (Protonotaria Citrea), Tyler A. Hohenstein

Theses and Dissertations

In this study I attempted to further resolve the population genetic structure in the Prothonotary Warbler (Protonotaria citrea), and conducted an outlier SNP analysis and exploratory gene ontology analysis to investigate potential ongoing natural selection in the species. This analysis of population structure confirms previous work by DeSaix et al. (2019), where weak population structure was observed between eastern sites along the Atlantic Coastal Plain, and western sites in the Mississippi Alluvial Valley, possibly due to a genetic discontinuity across the Appalachian Mountains. I conducted two forms of outlier SNP analyses, a principal component analysis (PCA)-based approach to identify SNPs …

Movement, Home Ranges, And Population Estimates Of Spotted Turtles (Clemmys Guttata) During A Rainy Breeding Season In Virginia, Lauren J. Jurczak

Theses and Dissertations

Spotted turtles (Clemmys guttata) use a complex of wetland and terrestrial habitats for survival and reproduction. Precipitation expands and creates larger and more numerous ephemeral pools available to spotted turtles on the landscape. In this study, I investigated the effects of precipitation on movement patterns and ephemeral pool usage by spotted turtles in southeastern Virginia. I conducted a 4-month capture-mark-recapture study alongside a telemetry study to estimate population size and to quantify movement of spotted turtles across the landscape during the breading season. A change point analysis was used to detect discrete changes in turtle behavior and whether …

Morphological Assessment And Mitochondrial Dna Analysis Of Roadside-Skippers (Genus Amblyscirtes, Family Hesperiidae) Occurring In Arkansas, Sachith Srikanth

Theses and Dissertations

Amblyscirtes linda is a candidate for federal listing under the Endangered Species Act (1973). The present study, funded by the U.S. Fish and Wildlife Service and the Arkansas Game and Fish Commission, aims to gather data that will enable a decision regarding federal listing to be made. It is understood that the conservation status of Amblyscirtes linda cannot be accurately assessed without examining other congeneric species with which it cooccurs and can be easily confused. This confusion is due to morphological characteristics being very similar in the genus. We therefore studied morphological and molecular means of identification, as well as …

Assessment Of Wild Ring-Tailed Lemur (Lemur Catta) Populations In Southwestern Madagascar With Implications For The Illegal Pet Trade, Samantha D. Calkins

Theses and Dissertations

Accurate population estimates are critical to inform conservation management of species. Incomplete sampling can lead to population underestimates and lacking conservation efforts. Population surveys are important for assessing human and animal welfare to allow for targeted conservation action. Recent ring-tailed lemur (Lemur catta) surveys have led researchers to conclude that L. catta populations are crashing. This has generated much attention and alarm, but may also be based on incomplete information. To better understand population dynamics, more thorough sampling is needed. Here, we survey five such sites to reassess the presence and abundance of L. catta in these locations. …

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 …

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 …

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. …

Red-Headed Woodpecker Full Annual Cycle Ecology At Fort A.P. Hill, Virginia, Benjamin Nickley

Theses and Dissertations

The red-headed woodpecker is a primary cavity excavator found throughout the Eastern Deciduous Forest and parts of the Great Plains. Although widespread, the red-headed woodpecker is generally considered uncommon, with patchily distributed populations. Over the past 50 years, this species has experienced precipitous, range-wide declines. The red-headed woodpecker uses a variety of cover types to meet resource needs across the annual cycle, ranging from oak savannas and wetlands, to mature beech forests and urban parks. Given their apparent adaptability to such a wide range of habitats, causes of declines are perplexing. To understand and stem declines, recent studies have focused …

Natural And Anthropogenic Drivers Of Tree Evolutionary Dynamics, Brandon M. Lind

Theses and Dissertations

Species of trees inhabit diverse and heterogeneous environments, and often play important ecological roles in such communities. As a result of their vast ecological breadth, trees have become adapted to various environmental pressures. In this dissertation I examine various environmental factors that drive evolutionary dynamics in threePinusspecies in California and Nevada, USA. In chapter two, I assess the role of management influence of thinning, fire, and their interaction on fine-scale gene flow within fire-suppressed populations of Pinus lambertiana, a historically dominant and ecologically important member of mixed-conifer forests of the Sierra Nevada, California. Here, I find evidence …

A Comparative Analysis Of Geometric Morphometrics Across Two Pseudemys Turtle Species In East Central Virginia, Kristin C. Dillard

Theses and Dissertations

The phylogeny of the turtle genus Pseudemys is poorly understood. In Virginia, many turtles have been found with indicator traits of both eastern river cooters (Pseudemys concinna concinna) and northern red bellied cooters (Pseudemys rubriventris). This study explores morphological evidence for hybridization between the two species across three riverine sites in east central Virginia.

Museum voucher groups for each species were analyzed for relative shell height and plastron length. The shape of the plastral scutes and upper jaw were analyzed using landmark-based morphometric software. These metrics were compared with measurements taken from 188 field-caught Pseudemys specimens. …

The Effects Of Disturbance And Species Specific Interactions On Diversity In An Agent Based Forest Simulation, Matthew E. Mills

Theses and Dissertations

In ecology literature, there is much data which suggests that conspecific negative density dependence (CNDD) and abiotic disturbances increase biodiversity in forests. This thesis elucidates the notion that not only do these two forces increase diversity, but they may also interact with one another in order to achieve higher levels of biodiversity. Abiotic disturbances, like fires and hurricanes, can indirectly impact conspecific effects because when these forces remove individuals from the landscape, the role of the conspecific effects will change. The interaction of these two factors in biodiversity are explored in an agent based forest simulation through a resource surface. …

Host Densities And Parasitism Rates In A Forest Defoliator Across A Rural-Urban Landscape, Abigail J. Nelson

Theses and Dissertations

Fall cankerworm (FCW) outbreaks have recently increased in frequency and intensity in the mid-Atlantic region of the United States, especially around cities of Charlotte, NC and Richmond, VA. This study evaluated the effects of two landscape features associated with urbanization, impervious surface and forest cover, on population patterns of FCW and its parasitoids across eastern Virginia. Forest cover was positively related to parasitism rates while impervious surface was positively related to FCW abundance, suggesting that FCW outbreaks may be amplified in urban areas. FCW abundance declined over the two-year period of this study, but parasitism rate increased at most sites. …

Genome Wide Epigenetic Analyses Of Araptus Attenuatus, A Bark Beetle, Chitra Seshadri

Theses and Dissertations

Phylogeographic studies have relied on surveying neutral genetic variation in natural populations as a way of gaining better insights into the evolutionary processes shaping present day population demography. Recent emphasis on understanding putative adaptive variation have brought to light the role of epigenetic variation in influencing phenotypes and the mechanisms underlying local adaptation. While much is known about how methylation acts at specific loci to influence known phenotypes, there is little information on the spatial genetic structure of genome-wide patterns of methylation and the extent to which it can extend our understanding of both neutral and putatively adaptive processes. This …

Effects Of Land Management On Mammalian Species Abundance And Richness Among Four Sites In West-Central Georgia, Kelsey A. Champagne

Theses and Dissertations

No abstract provided.

A Scent-Station Survey Of Medium-Size Mammals On The Callaway Preserve, Harris County, Georgia, Anna-Maria Giacobello

Theses and Dissertations

The objective of this project was to determine the relative abundance of medium- sized mammals on the Callaway Preserve in Harris County, Georgia, using the scent- station technique, to determine species preference in regard to habitat, to compare relative abundance of species in regard to habitat, and to compare habitats in terms of the species present. Thirty-six scent-stations were established on the property and monitored to observe the presence of coyotes, raccoons, armadillos, foxes, opossums, and skunks. Of the total number of visits to the scent-stations, 36.36 % were coyotes, 18.18% were foxes 22.73% were armadillos, and 22.73% were raccoons. …

A Taxonomical, Morphological And Distributional Study Of The Utah Cyprinidae /|Cby Sheldon Phipps Hayes, Sheldon Phipps Hayes

Theses and Dissertations

The hydrography of Utah may be thought of as being roughly divided into two large general drainage areas--, the Colorado River draining the eastern halt and southern portion ot the state and the Bonneville Drainage encompassing the remaining part of it. Earlier workers have listed eight genera and fourteen species of minnows occuring in Utah. Of these this report includes seven genera and ten species found within the borders of our state.