Population Biology Commons^™

Epigenetic Potential Remains Stable Over 100 Years After Introduction, Danielle Dawkins

College of Graduate Studies: Theses & Dissertations

Introduced species provide important insights into organismal behavioral responses. Epigenetic mechanisms are one of the various ways in which behaviors can be modified, particularly through DNA methylation. Through such mechanisms, phenotypic changes can occur in response to environmental changes, allowing an organism to be more plastic. Epigenetic potential (EP) represents the capacity for an organism to be epigenetically modified, and can be measured by counting CpG motifs; cytosine adjacent to guanine within a DNA sequence. Phenotypic plasticity as it relates to EP has been studied extensively in the house sparrow (Passer domesticus), a globally introduced songbird. It is …

Exploring Coastal Plain Fish Ecology Across A Range Of Early-Life-History Traits And River Types, Bridgette Nicolosi

College of Graduate Studies: Theses & Dissertations

The ecological complexity of southeastern Coastal Plain rivers is reflected in the diversity of fish communities they support, yet the processes structuring early life dynamics remain poorly understood. This thesis explores the influence of environmental gradients on larval fish assemblage composition and American Shad (Alosa sapidissima) spawning phenology across two Georgia Coastal Plain river systems.

In the unregulated Ogeechee River, I investigated spatial and temporal variation in larval fish communities by comparing mainstem and tributary habitats to understand the role of tributaries in watershed-wide larval production. Larvae were collected biweekly from May to September 2024 at eight paired mainstem-tributary sites …

A Comparison Of Microsatellites And Single Nucleotide Polymorphisms For The Assessment Of Population Structure In The Amblyomma Maculatum Koch, 1844 Species Complex, Henrey A. Deese

Electronic Theses and Dissertations

The Gulf Coast tick, Amblyomma maculatum Koch, 1844 is widespread throughout North and Central America and is the primary vector for the emerging pathogen Rickettsia parkeri. In the U.S., the population in the Southwest (A. maculatum morphotype III) is morphologically different from the population east of the Rocky Mountains (A. maculatum morphotype II). This research tests the hypothesis that A. maculatum morphotype II and morphotype III represent distinct species through the analysis and comparison of 6 microsatellite loci and suite of 135,221 Single nucleotide polymorphisms (SNPs) generated from ddRADseq. Population genetic analysis of both microsatellites and SNPs …

The Potential Role Of Phenotypic Plasticity In The Ability Of Hydrocotyle Bonariensis To Occupy Two Different Habitats, Harold Ralph Parsons Iii

Honors College Theses

Phenotypic plasticity is the ability of an organism to change morphology and/or physiology in response to changes in the environment. Hydrocotyle bonariensis is a coastal perennial herb found in both coastal sand dunes and inland coastal plain habitats in Georgia. The purpose of this study was to determine if there were differences in leaf morphology for populations of H. bonariensis in coastal sand dune and inland coastal plain habitats. Leaf morphology and microenvironmental variables were compared between H. bonariensis populations at Tybee Island (TI), GA, representing the coastal sand dune habitat, and Georgia Southern University Armstrong Campus (GSU) in Savannah, …

Florida Sand Skink And Blue-Tailed Mole Skink: Expanding Geographic Coverage Of Genetic Analysis For Conservation, Emma Simpson

College of Graduate Studies: Theses & Dissertations

The Lake Wales Ridge is important scrub habitat that has been increasingly altered since the post-Columbian settlement in Florida. This loss of habitat has caused extreme anthropogenic fragmentation within the Lake Wales Ridge resulting in isolation among extant scrub patches. To expand the geographic scope of previous studies and answer questions concerning population connectivity, we characterized genetic diversity and differentiation using cytochrome-b and microsatellite genetic markers for two endemic skink species: the Florida Sand Skink (Plestiodon reynoldsi) and Blue-tailed Mole Skink (Plestiodon egregius lividus). Both species display historical isolation between central and southern Lake Wales Ridge …

Population Genomics Of Redbreast Sunfish (Lepomis Auritus): Exploring Gene Flow And Local Adaptation In A Widely Distributed Freshwater Fish, Garret J. Strickland

College of Graduate Studies: Theses & Dissertations

Little information is available concerning the distribution of genetic diversity in non-salmonid, non-imperiled, freshwater fish. In order to fill in this knowledge gap, I conducted a population genomics survey in Redbreast Sunfish (Lepomis auritus; RBS), a widespread, generalist species distributed along the Atlantic slope rivers of eastern North America. I sampled four basins (ACF, Savannah, Roanoke, and James) at eight sites each with a factorial experimental design. Sites were distributed among coastal plain, Piedmont, or mountain ecoregions in order to capture the greatest range of environmental states experienced by RBS, with the intention of finding evidence for local adaptation to …

Comparative Conservation Genomics Of A Suite Of Imperiled Freshwater Mussels, Scott C. Meyer

College of Graduate Studies: Theses & Dissertations

Maintenance of genetic diversity is a critical component to the management and recovery of imperiled species. By ensuring that a species’ genetic diversity is maintained, issues like inbreeding depression and loss of local adaptation can be prevented. However, the genetic diversity of many species are not well-characterized, and the factors that influence a species’ genetic diversity are often not well understood. In the case of imperiled unionid freshwater mussels, it is important to conduct conservation genetic assessments to aid in their management and preserve genetic diversity. This is the first study to conduct a comparative conservation genomic assessment for eight …

Assessing Habitat Suitability Of Ribbed Mussels (Geukensia Demissa) In Georgia Salt Marshes By Examining Predicted Mussel Densities And Mussel Population Parameters, William K. Annis Jr

College of Graduate Studies: Theses & Dissertations

Geukensia demissa (ribbed mussel) is an ecology important bivalve that has the potential to contribute to salt marsh restoration. Understanding the factors that contribute to the distribution of mussels can help inform managers on choosing locations to optimize the survivorship of mussels in restoration projects. This study sought to model mussel densities across the coast of Georgia and to compare predicted mussel densities with mussel population parameters as means to gauge habitat suitability. Mussel densities were collected through field surveys across a range of salt marshes along the coast of Georgia and were compared with spatial data such as distance …

Impact Of Seasonal And Host-Related Factors On The Intestinal Microbiome And Cestode Community Of Sorex Cinereus And Sorex Monticola, Katelyn D. Cranmer

College of Graduate Studies: Theses & Dissertations

The intestinal microbiome of mammals plays a significant role in host health and response to environmental stimuli and can include both beneficial native bacteria as well as parasitic worms. In this study, I examined the intestinal cestode and bacterial communities of two closely related species of shrew, Sorex monticola and Sorex cinereus, over a six month period in 2016. Specimens were collected approximately every three weeks from May to October from the Sangre de Cristo Mountains in Cowles, New Mexico. A total of 79 shrews were prepared with the gastrointestinal tracts removed and flash-frozen in liquid nitrogen. An additional …

Testing Viability Of Oligonucleotide Primers On Microsatellite Markers Amplified By Polymerase Chain Reaction On Dermacentor Variabilis Samples From The Bulloch County Region Of Georgia, Usa, Danielle Souza

Honors College Theses

Dermacentor variabilis, more commonly known as the wood tick, or the American dog tick, can be found all over North America. D. variabilis is a common tick in Bulloch county, Georgia, USA, and little is known about the population structure of this population of the species. Microsatellite markers are able to locate sections of the genome and can aid in estimating relatedness among individuals in a population. Six different oligonucleotide primer pairs were published for D. variabilis, however, published and non-published works indicated that not all of those primer pairs were working equally well for PCR. This study is …

Comparison Of Three Benthic Macroinvertebrate Passive Sampling Devices For Non-Wadeable Streams, Kelsey A. Laymon

College of Graduate Studies: Theses & Dissertations

Rivers and streams provide essential ecosystem services to the degree that the monitoring and maintenance of these systems becomes imperative. Biomonitoring provides managers and policymakers with the tools to make informed decisions, and macroinvertebrates are often the object of biomonitoring because they are ubiquitous in most systems and are known to be good indicators of water quality. However, methods for sampling macroinvertebrates in non-wadeable streams (i.e., large rivers) have not been standardized across states and regions and an established method for macroinvertebrate biomonitoring in large rivers of Georgia is not currently available. My study compared macroinvertebrates collected with three types …

Characterizing The Complex Relationship Between The Brown Widow Spider And Its Bacterial Endosymbiont, Wolbachia, Emily Knight

College of Graduate Studies: Theses & Dissertations

The brown widow spider, Latrodectus geometricus (C. L. Koch 1841), has been found to harbor the maternally inherited bacterial endosymbiont Wolbachia pipientis (Hertig and Wolbach 1924), but endosymbiont infection frequency varies widely among Southeastern US populations. Wolbachia is known to manipulate the reproduction of its hosts through male feminization, parthenogenesis, male killing, and cytoplasmic incompatibility. In brown widows, Wolbachia does not alter sex ratios, but any other effects the symbiont has on the spider are unknown. In my first chapter, I assess if there is linkage between Wolbachia infection and maternally inherited mitochondrial DNA (mtDNA) in three brown widow populations. …

Foraging Ecology Of A Winter Bird Community In Southeastern Georgia, Rachel E. Mowbray

College of Graduate Studies: Theses & Dissertations

Classical views on community structure emphasized deterministic processes and the importance of competition in shaping communities. However, the processes responsible for shaping avian communities remain controversial. Attempts to understand distributions and abundances of species are complicated by the fact that birds are highly mobile. Many species migrate biannually between summer breeding grounds and wintering grounds. The goal of this study was to test four hypotheses that attempt to explain how migratory species integrate into resident assemblages of birds (Empty-Niche Hypothesis, Competitive-Exclusion Hypothesis, Niche-Partitioning Hypothesis, and Generalist-Migrant Hypothesis). I collected data on birds foraging during the winter of 2017-2018 in Magnolia …

Evolutionary Linkage Of Mimetic And Non-Mimetic Color Traits In A Coral Snake Mimicry Complex, John D. Curlis Jr

College of Graduate Studies: Theses & Dissertations

Color polymorphism in aposematic mimicry systems is a perplexing phenomenon for evolutionary biologists, as theoretically the benefits of converging on a model phenotype should constrain the evolution of phenotypic diversity in these systems (i.e., color polymorphism should not occur). Nevertheless, color polymorphism in mimicry systems is prevalent throughout many taxa. In some of these systems, the evolution of color polymorphism results in the existence of non-mimetic morphs, such as those that are cryptic. The case of ground snakes (Sonora semiannulata) is unique in that color polymorphism encompasses both mimetic and cryptic morphs, as well as individual mimetic and …

Inbreeding Depression In The Introduced Spider Latrodectus Geometricus, Margaret A. Howard

Honors College Theses

The brown widow spider (Latrodectus geometricus) is thought to be native to South America or Southern Africa, but its distribution has expanded to most continents by human introduction. In the continental USA, L. geometricus was first documented in south Florida in the 1930’s. In the early 2000’s a population expansion occurred, and this species is now found in Florida, Georgia, South Carolina, Alabama, Mississippi, Louisiana, Texas, and southern California. Introduced species may face many obstacles when establishing a new population. One common obstacle might be severe inbreeding following founder events or genetic bottlenecks. The purpose of this study was …

Determining The Reproductive Patterns Of The Titan Acorn Barnacle (Megabalanus Coccopoma) In Its Introduced Range, Isabel L. Moran Ms.

Honors College Theses

Invasive species are a significant conservation concern given their contribution to native species decline. The barnacle, Megabalanus coccopoma, is a common invasive species in tropical and subtropical regions of both the Pacific and Atlantic oceans. Little is known about the life history and ecology of M. coccopoma, and data on reproductive biology could provide valuable insight into its propensity to establish introduced populations. Most species of barnacle (including M. coccopoma) are hermaphroditic, but self-fertilization is rare in species studied to date. A recent genetic study of introduced M. coccopoma populations in the southeastern US showed high levels of …

A Population Genetic Investigation Of The Reticulated Flatwoods Salamander (Ambystoma Bishopi) On Eglin Air Force Base, Alexander S. Wendt

College of Graduate Studies: Theses & Dissertations

The reticulated flatwoods salamander (RFS) is an endangered salamander with a unique life history. One of the largest known, best studied refuges for RFS is found on Eglin Air Force Base, and these RFS have been sampled and managed extensively since 2010. My thesis seeks to better understand RFS by using genetic techniques to address several unknowns, including: 1) determining the population structuring of RFS and the manageable units for species conservation, 2) estimating the size and status of populations, 3) understanding dispersal of RFS and factors that influence this, 4) exploring the breeding biology and recruitment patterns of RFS …

A Morphological And Genetic Analysis Of Forensically Important Blow Flies, From Georgia: The Genus Lucilia, Katie S. Googe

Honors College Theses

Identification of Blow flies (Diptera: Calliphoridae) to species is important for estimating postmortem intervals, because insect species develop at different rates. Three Blow fly species in Georgia; Lucilia coeruleiviridis, L. cuprina, and L. sericata are similar morphologically, making identification difficult. Furthermore, the status of L. cuprina is in doubt; this species may be a complex of true L. cuprina, and L. cuprina x L. sericata hybrids. The objective of this study was to survey the Georgia Blow fly community and validate the statuses of L. coeruleiviridis, L. cuprina, and L. sericata, through morphological and …

The Prevalence And Effect Of Wolbachia Infection On The Brown Widow Spider (Latrodectus Geometricus), Brittany Dane' Arrington

College of Graduate Studies: Theses & Dissertations

Wolbachia was recently identified in the Brown Widow Spider (Latrodectus geometricus). This symbiont has not previously been found in this genus, therefore the consequences on the host’s population dynamics are unknown. The frequency of endosymbiont infection can provide insight into the population dynamics of the host as this bacteria is known to alter host life history. In my 1^st chapter I determine the prevalence of Wolbachia pipentis infection in in the Brown Widow Spider (Latrodectus geometricus) from five locations in the Southeastern United States. Infection frequency differed significantly among sampling locations, ranging from 20% to …

Epistasis In Predator-Prey Relationships, Iuliia Inozemtseva

College of Graduate Studies: Theses & Dissertations

Epistasis is the interaction between two or more genes to control a single phenotype. We model epistasis of the prey in a two-locus two-allele problem in a basic predator- prey relationship. The resulting model allows us to examine both population sizes as well as genotypic and phenotypic frequencies. In the context of several numerical examples, we show that if epistasis results in an undesirable or desirable phenotype in the prey by making the particular genotype more or less susceptible to the predator or dangerous to the predator, elimination of undesirable phenotypes and then genotypes occurs.

Tactical Escape Behavior And Performance Of A Small Sceloporine Lizard In Two High Risk Habitats, Seth Parker

College of Graduate Studies: Theses & Dissertations

The negotiation of uneven and complex terrain has implications for many small terrestrial vertebrates. Variation in the running surface due to obstacles like woody debris or vegetation can alter escape paths and running performance. Additionally, these microhabitat features can influence behavioral tactics in complex environments. The ability to negotiate physical barriers in dense environments likely influences survivorship through important ecological tasks, such as finding mates, foraging, and evading predators. The Florida scrub lizard (Sceloporus woodi) is a small, rare species endemic to two distinct and structurally complex environments in Florida, i.e. sand-pine scrub and longleaf pine-wiregrass sand-hills. The …

Variation In Population Densities Of The Florida Scrub Lizard (Sceloporus Woodi) Between Managed Sand Pine Scrub And Longleaf Pine Stands In The Ocala National Forest, Matthew D. Kaunert

College of Graduate Studies: Theses & Dissertations

Population-level response to habitat fragmentation is central to applied species management and conservation. Managed landscapes are often subject to increased fragmentation and, consequently, may force once connected populations to function as metapopulations. Studies investigating metapopulations occurring over patchy, managed landscapes are of increasing importance as fragmentation is a known cause of biodiversity loss. In June-September 2012, populations of the rare, endemic Florida scrub lizard (Sceloporus woodi) were sampled across the Ocala National Forest (ONF) to compare abundance and density across two management types. In the ONF, sand-pine scrub is clearcut and rollerchopped whereas longleaf pine is managed via …

Waterhole Dynamics And Chemical Signals Of African Elephants ( Loxodonta Africana ), Stacie Marie Castelda

College of Graduate Studies: Theses & Dissertations

The distribution of mammals in a savanna environment is influenced by abiotic and biotic factors. The African savanna experiences distinct wet and dry seasons. Species become spatially restricted around water resources during the dry season, resulting in increased intraspecies and interspecies resource-based aggregation. A dominate species, such as the African elephant (Loxodonta africana), may influence this aggregation. I examined the influence of wet and dry seasons and ambient temperature on the use of a waterhole by elephants as well as the co-occurrence of elephants and other mammals at the waterhole. Biodiversity scans (October 2004-June 2007) and were performed at a …

The Winter Ecology Of The Piping Plover (Charadrius Melodus) In Coastal Georgia, Brandon Lennon Noel

College of Graduate Studies: Theses & Dissertations

Author's abstract: The Piping Plover (Charadrius melodus) is a federally listed species with three distinct breeding populations, including Great Plains (threatened), Great Lakes (endangered), and Atlantic Coast (threatened), all of which winter along the Atlnatic and Gulf coasts of the United States. I studied the winter ecology of the Piping Plovers on Little St. Simons Island (LSSI), Georgia, from 2003-2006, with emphasis on the conservation significance of this site for the endangered Great Lakes population. During 2003-2004 and 2004-2005, LSSI supported up to 100 Piping Plovers during peak migration, and approximately 40 birds wintered at this site. All populations had …