Ecology and Evolutionary Biology Commons^™

Delineating Metrics Of Diversity For A Snake Community In A Rare Ecosystem, Zachary John Marcou

Electronic Theses and Dissertations

Snakes are among the least understood vertebrate groups despite their considerable diversity. A diverse community of snakes in an ecosystem can indicate a complex habitat structure that is capable of supporting a robust assemblage of other biota. I used remote photography arrays (RPA) to quantify metrics of diversity for the snake community occurring in a ~7,000–ha tract of contiguous Longleaf Pine (Pinus palustris) Savanna within the Angelina National Forest (ANF; Angelina and Jasper Cos., TX), over the course of two consecutive snake activity seasons. I quantified the snake species richness, Shannon diversity, and Shannon equitability for the snake community in …

Hydrodynamic Drivers Of Dissolved Oxygen Variability Within A Highly Developed Tidal Creek In Myrtle Beach, South Carolina, Douglas Matthew Pastore

Electronic Theses and Dissertations

Erosion and water quality degradation have been observed in Singleton Swash in Myrtle Beach, SC, and have been hypothesized to be related to migration of the beach-face channel. Dredging this channel temporarily fixes erosional threats to nearby infrastructure but the effects on water quality are not well understood. It is hypothesized that variations in dissolved oxygen (DO) concentration (used here as a proxy for water quality) within the water column are related to changes in vertical mixing and transport due to oceanic tidal forcing. This study utilizes current meters, pressure sensors, and optical DO probes to measure and study the …

Diel Rhythmicity Found In Behavior But Not Biogenic Amine Levels In The Funnel-Web Spider Agelenopsis Pennsylvanica (Araneae, Agelenidae), Alexander E. Demarco

Electronic Theses and Dissertations

Quantifying individual differences in behavior and the extent that behavior is influenced by circadian control is of paramount importance in behavioral ecology. In addition, the proximate mechanisms underlying behavior are also critical in order to obtain a more complete picture of how behavior evolves. Biogenic amines (BAs) are simple nitrogenous compounds derived from amino acids and have been consistently and extensively linked to behavior. For this study, we analyzed temporal patterns of BAs in relation to the antipredator (boldness) and aggressive behavior in female Agelenopsis pennsylvanica, a funnel-web spider. Using HPLC-ED, we compared behavioral responses to temporal patterns of …

Escaping The Arrhenius Tyranny: Metabolic Compensation During Exposure To High Temperature In Daphnia, Bret L. Coggins

Electronic Theses and Dissertations

Poikilothermic organisms experience trade-offs by differential physiological demands generated by temperature extremes. Many such organisms exhibit acclimatory effects, adjusting their metabolism and physiology to recently experienced temperatures. One such acclimatory effect is metabolic compensation, the deceleration of biological rates below Arrhenius expectations. Daphnia magna is eurythermal, and if acclimated to mildly stressful temperatures first, survives longer in lethal temperatures. This study examined the effect of ambient temperature (5°C-37°C) and acclimation history (lifetime at 10°C or 25°C) on the oxygen consumption rates of 8 genotypes of Daphnia with high or low acute temperature tolerance. There were decelerations of respiratory rates across …

The Effects Of Habitat And Connectivity On Tropical Ant Ecology And Behavior., Benjamin Jacob Adams

Electronic Theses and Dissertations

This dissertation explores the role that physical connections among and within habitats play in determining the local diversity and behaviors of cursorial organisms. Understanding the processes that regulate local community assembly and that contribute to the maintenance of species diversity is a cornerstone of community ecology. Ants are a useful model for studies of local communities because they are abundant and fulfill a variety of ecological roles. Chapter one of the dissertation examines the how lianas (woody vines) function as connective structures among tree crowns and how these connections affect arboreal ant community structure within a tropical forest canopy. Trees …

Soil Ecology Of The Exotic Dune Grass Leymus Arenarius., Matthew L. Reid

Electronic Theses and Dissertations

Exotic plants can alter the structure and function of native communities both above- and belowground, which is particularly important in primary successional sand dune ecosystems where plant-soil interactions are critical drivers of successional dynamics. In Great Lakes sand dunes, the native foundation grass Ammophila breviligulata dominates early in succession until an accumulation of detrimental soil organisms causes its die-back of the grasses. Die-back of this native foundation species can be slowed by mutualistic interactions between plants and mycorrhizal fungi. Changes to the plant community resulting from invasion, and subsequent effects on the soil community have the potential to disrupt the …

Tidal Creek And Substrate Effects On Oyster Reef Associated Fish And Decapod Condition And Density, Thomas S. Funk

Electronic Theses and Dissertations

Oyster reefs are essential fish habitat and a worldwide loss of reefs has the potential to negatively affect reef-associated nekton populations. Along the 100 km Myrtle Beach, SC shoreline, oyster reefs ostensibly have disappeared within swash tidal creeks, which are anthropogenically altered estuarine systems that drain into the coastal ocean directly over shoreline beaches. To address oyster reef losses, a series of shell bag reefs were constructed within multiple swash tidal creeks. Reefs also were constructed in tidal creeks associated with estuaries directly connected to the ocean by an inlet. The purpose of this study was to compare nekton usage …

Diet Breadth Evolution And Diversification Of A Generalist Insect Herbivore, Mayra Cadorin Vidal

Electronic Theses and Dissertations

Insect herbivores are one of the most diverse groups of multicellular organisms, and the vast majority are specialists, which feed on only a few plant species. The factors that cause some herbivores to be specialists and others to be generalists are still unclear. It is known that the selective forces from natural enemies (top-down) and the host plants (bottom-up) influence an herbivore's diet breadth. In my meta-analysis evaluating the relative important of top-down and bottom-up forces on insect herbivore fitness, I found that herbivores usually have greater performance on better quality plants and in the absence or reduction of enemy …

Social Conflict On The Seas: Links Between Overfishing-Induced Marine Fish Stock Declines And Forced Labor Slavery, Jessica L. Sparks

Electronic Theses and Dissertations

Despite media attention detailing labor abuses in fisheries, social-ecological systems research has largely failed to consider whether fish stock declines could be contributing to increases in forced labor slavery. Empirical fisheries data suggests, though not a ubiquitous response to declining stocks, many vessels will fish longer, farther from shore, and deeper in waters to maintain yields. This effort intensification increases production costs, and Brashares et al. (2014), consistent with slavery theory, posited cheap and/or unpaid labor as an approach to offset increasing costs and continue harvesting fish species at a rate otherwise cost-prohibitive.

Using fuzzy cognitive mapping - a participatory, …

Effects Of Anthropogenic Noise On Mating Behavior And Fitness, Gabrielle A. Gurule-Small

Electronic Theses and Dissertations

When environments change rapidly, adaptive phenotypic plasticity can ameliorate negative effects of environmental change on survival and reproduction. Recent evidence, however, suggests that plastic responses to human induced environmental change are often maladaptive or insufficient to overcome novel selection pressures. Anthropogenic noise is a ubiquitous and expanding disturbance with demonstrated effects on fitness-related traits of animals like stress responses, foraging, vigilance, and pairing success. Elucidating the lifetime fitness effects of noise has been challenging because long-lived vertebrate systems are typically studied in this context. In both chapters described herein, I reared field crickets, Teleogryllus oceanicus, in masking traffic noise, …

Origins Of Animal Cell Adhesion, Jennyfer Mora Mitchell

Electronic Theses and Dissertations

A fundamental requirement for multicellularity is cell adhesion. This includes mechanisms by which cells adhere to each other and to their secreted extracellular matrix (ECM). Two well characterized adhesion complexes in animals include: 1) adherens junctions (AJs), which are involved in cell-cell adhesion and composed of cadherin receptors, p120-, α- and β-catenin, and 2) focal adhesions (FAs), which are involved in cell-ECM adhesion and include proteins such as integrins, vinculin, paxillin, talin and focal adhesion kinase (FAK). The molecular components of AJs are widely conserved in animals, and largely absent in non-animals. In contrast, the molecular components of FAs have …

Evaluation Of Methods Used To Improve Grasslands As Ring-Necked Pheasant (Phasianus Colchicus) Brood Habitat, Mandy Orth

Electronic Theses and Dissertations

Management practices designed for upland game species often focus on nest survival and hen winter survival due to the importance of these life history stages on population vital rates. However, chick survival is an important component of gallinaceous bird population dynamics, but it is poorly understood and often tends to be overlooked. Ideal brood habitat not only provides open understory for easy movement and canopy cover for protection, but also provides an abundance of arthropod foods for chicks. It has been hypothesized that restricted movement of chicks through thick vegetation in unmanaged grasslands results in lower brood survival rates. Research …

Evaluating Bighorn Sheep Herd Response After Selective Removal Of Mycoplasma Ovipneumoniae Chronic Shedders, Tyler J. Garwood

Electronic Theses and Dissertations

Infected individuals vary in their contribution to disease persistence, and chronically infected individuals may sustain disease in a population. One disease that might persist in a population through chronically infected individuals is pneumonia in wild sheep. Mycoplasma ovipneumoniae (Mo), a pathogen of Caprinae commonly present in domestic sheep and goats, strongly correlates with pneumonia epizootics when it infects wild sheep populations. These epizootics can cause 40-100% herd mortality in an initial all-age dieoff, precipitate annual lamb mortality as high as 100% in following years, and sustain adult mortality long after initial all-age dieoffs. We conducted an experiment in the Black …

Black-Tailed Prairie Dog (Cynomys Ludovicianus) State-And-Transition Model For Loamy Ecological Sites In Mlra 62 In Custer State Park, South Dakota, Mark R. Hendrix

Electronic Theses and Dissertations

Black-tailed prairie dogs (Cynomys ludovicianus) are native burrowing rodents that occupy large areas in the shortgrass and mixed-grass prairies of the Northern Great Plains. They are an important component of these prairie systems due to their impacts on plant communities. Currently State-and-Transition models (STMs) for grassland Ecological Site Descriptions (ESDs) address grazing by livestock as a major factor affecting states and phases within states. Impacts from other grazers, such as prairie dogs, are either not addressed directly, or are included only in a transition to a generalized early seral state. There are, however, dramatic differences in plant communities …

Vulnerability Of Protected Areas To Human Encroachment, Climate Change And Fire In The Fragmented Tropical Forests Of West Africa, Francis Kwabena Dwomoh

Electronic Theses and Dissertations

The Upper Guinean region of West Africa is home to some of the most globally significant tropical biodiversity hotspots, providing ecosystem services that are crucial for the region’s socio-economic and environmental wellbeing. Nonetheless, following decades of human-caused destruction of natural habitats, protected areas currently remain the only significant refugia of original vegetation relics in landscapes that are highly fragmented. Aside from having strong geographic variation in land use, climate, vegetation, and human population, the region has also experienced remarkable biophysical and socio-economic changes in recent decades. All these factors influence the fire regime and the vulnerability of forests within protected …

Impacts And Implications Of Polytypism On The Evolution Of Aposematic Coloration, Justin Philip Lawrence

Electronic Theses and Dissertations

Aposematic signaling is a comdefensive strategy whereby prey species use conspicuous signals (i.e., bright coloration) to warn predators of the risks of predation due to a secondary defense. Theoretical, lab, and field experiments have demonstrated that individuals who project novel conspicuous signals should experience disproportionately high predation pressure as predators will not associate novel signals with a secondary defense. Thus, aposematic signaling should be subject to strong positive frequency-dependent selection (FDS). Numerous species show considerable intrapopulation variation (polymorphism) in direct conflict with the expectations of FDS. Interpopulation variation (polytypism) can adhere to expectations of FDS, but as its origins likely …

The Effect Of Environmental Perturbations On The Plant Phyllosphere Microbiome, Bram W. Stone

Electronic Theses and Dissertations

Applying ecological concepts to microbial communities has proved to be challenging, often revolving around the relative importance of stochastic and deterministic processes applied heterogeneously across the habitat in time or space. The phyllosphere is the aboveground surface of plants on which microbial communities, composed primarily of Bacteria, but also including Archaea and microbial eukaryotes, exist and is characterized by stochastic immigration balanced with strong selective forces. Variation in bacterial community composition was characterized across space and time, with special attention given to the exposure of phyllosphere communities to rain as a plausible mechanism of ecological disturbance. Bacterial communities were characterized …

The Ecology Of Land Managers In Riparian Restoration, Lisa Buie Clark

Electronic Theses and Dissertations

While previous studies in restoration ecology have focused on the efficacy of direct management actions, the driving forces on management decisions (e.g., managers' characteristics or attitudes, environmental conditions) and the indirect impacts on restoration outcomes from management decisions (such as whether to collaborate) are quantified here for the first time. As a case study, I used data from 244 sites across the riparian Southwest US where the invasive shrubby tree Tamarix sp. was removed using various different methods. I surveyed and interviewed the 45 land managers who were responsible for the removal projects to determine their characteristics, attitudes, and …

Estimating Density And Residency Of Bottlenose Dolphins (Tursiops Truncatus) In Three Estuarine Sites In South Carolina, Jessica Nicole Conway

Electronic Theses and Dissertations

Of the three estuarine bottlenose dolphin stocks in South Carolina, two are considered data insufficient, with no minimum population estimate or assigned potential biological removal value. Additionally, the Northern Georgia Southern South Carolina Estuarine System (NGSSCES) stock’s boundaries are based on sighting data that do not extend to the full area encompassed by the boundary lines. In areas where stock boundaries are not clearly defined and data is insufficient for traditional methods of estimating abundance, density may provide insight into local distributions and serve as a proxy for actual abundance. Photo-identification surveys were conducted in three sites, representative of the …

Nonspreading Solutions In Integro-Difference Models With Allee And Overcompensation Effects., Garrett Luther Otto

Electronic Theses and Dissertations

Previous work in Integro-Difference models have generally considered Allee effects and over-compensation separately, and have either focused on bounded domain problems or asymptotic spreading results. Some recent results by Sullivan et al. (2017 PNAS 114(19), 5053-5058) combining Allee and over-compensation in an Integro-Difference framework have shown chaotic fluctuating spreading speeds. In this thesis, using a tractable parameterized growth function, we analytically demonstrate that when Allee and over-compensation are present solutions which persist but essentially remain in a compact domain exist. We investigate the stability of these solutions numerically. We also numerically demonstrate the existence of such solutions for more general …

Spatially Explicit Model Of Areas Between Suitable Black Bear Habitat In East Texas And Black Bear Populations In Louisiana, Arkansas, And Oklahoma, Caitlin M. Glymph, Christopher Comer, Daniel Scognamillo, Daniel Unger, Yanli Zhang

Electronic Theses and Dissertations

Although black bears (Ursus americanus, Ursus americanus luteolus) were once found throughout the south-central United States, unregulated harvest and habitat loss resulted in severe range retractions and by the beginning of the twentieth century populations in Oklahoma, Louisiana, Texas and Arkansas were nearing extirpation. In response to these losses, translocation programs were initiated in Arkansas (1958-1968 & 2000-2006) and Louisiana (1964-1967 & 2001-2009). These programs successfully restored bears to portions of Louisiana and Arkansas, and, as populations in Arkansas began dispersing, to Oklahoma. In contrast, east Texas remains unoccupied despite the existence of suitable habitat in the region.

To facilitate …

Enemy Exacerbation: Effects Of Predator Stress On Sulfate Lethality In Freshwater Amphipods (Gammarus Minus), Trevor Chapman

Electronic Theses and Dissertations

Predator cues can influence how aquatic organisms respond to anthropogenic contaminants. This study examined the effects of predator cues on behavior, metabolic rate, and sulfate (as Na₂SO₄) toxicity in amphipods (Gammarus minus). Predator cues included alarm cue (macerated conspecifics) and kairomone from mosquitofish (Gambusia affinis). Amphipods decreased activity and increased time in refuge when exposed to alarm cue, and increased time in refuge when exposed to kairomone. While median lethal concentrations (96-h LC₅₀) were not influenced by predator cues, analysis of dose response curves indicated that kairomone exposure increased amphipod …

Ecological Informatics: An Agent Based Model On Coexistence Dynamics, Shiva Thapa

Electronic Theses and Dissertations

The coexistence of species is probably one of the most interesting and complex phenomenon in nature. We constructed an agent based model to study the coexistence dynamics of prey - predator populations by varying productivity levels of producers in fragmented and connected habitats along with different levels of quality of predators. Our results indicated that productivity levels of producers in fragmented and connected habitats along with levels of predator quality are significantly responsible for overall predator - prey population size and survivorship. In the absence of predation, competition between identical prey populations is more probable in connected habitats than in …

Intraspecific Differences In Belowground Associations And Seedling Root Morphology For The Biofuel Crop, Panicum Virgatum., Erin Renee Kinnetz

Electronic Theses and Dissertations

The perennial C₄ grass Panicum virgatum (switchgrass) is a promising bioenergy feedstock. Switchgrass is symbiotic with arbuscular mycorrhizal fungi (AMF). I examined 12 varieties of switchgrass grouped into 2 ecotypes (upland, lowland) to see if they differed in AMF abundance and root colonization using the GLBRC Variety Trials experiment. There was higher root colonization of lowland ecotype. A greenhouse experiment evaluated the role of live soil organisms in seedling establishment of 11 varieties. Live soil increased seedling survival, growth and influenced root morphology. Ecotypes differed in root architecture. Lowland developed a higher specific root length (SRL), a trait associated …

Environmental Factors, Not Plants, Contribute To Functional Diversity Of Soil Bacteria In The Dunes Of Lake Michigan., Andrea Stark Howes

Electronic Theses and Dissertations

Soil bacteria play important roles in nutrient cycling and other ecosystem functions, and many biotic and abiotic factors can influence bacterial functional diversity. The goal of this field study was to examine differences among bacterial communities in sand dunes of Lake Michigan. I used Biolog Ecoplates™ to compare bacteria functional diversity associated with four different plant species: the native dune-building grass Ammophila breviligulata, invasive species Leymus arenarius and Gypsophila paniculata, and native legume Lathyrus japonicus across 13 sites in Michigan, representing a gradient in abiotic factors such as precipitation and temperature. I found no differences in bacterial function associated with …

Range-Wide Prevalence And Impacts Of Pseudocercosporella Inconspicua On Lilium Grayi And An Assessment Of L. Superbum And L. Michauxii As Reservoirs, Cindy L. Barrett

Electronic Theses and Dissertations

Lilium grayi (Gray’s Lily), a southern Appalachian endemic species, is threatened by a Lilium-specific fungal pathogen, Pseudocercosporella inconspicua. The disease is characterized by tan lesions that can cause early senescence, while also lowering seed production and viability. This project tested for P. inconspicua conidia and accessed health at nine locations. The disease was present and ubiquitous across the range of L. grayi. Through identification of P. inconspicua conidia in the field, L. superbum (Turk’s Cap Lily) was identified as an additional host, while L. michauxii (Michaux’s Lily) was disease-free. However, infection was inducible in both species. With …

Niche Modeling For The Giant Panda, Ailuropoda Melanoleuca, And The Original Panda, Ailurus Fulgens: Habitat Preferences And Evolutionary Consequences, Lauren M. Lyon

Electronic Theses and Dissertations

The well-known symbol for conservation, the giant panda bear, and the original red panda have been forced into remote habitats due to anthropogenic disturbance, making ecological study difficult. Therefore the first known species distribution model was created to predict the most likely areas of occurrence within the known range of these elusive animals. These models were then projected onto North America and evaluated against existing breeding programs. Additionally, the close proximity of the Gray Fossil Site and the discovery of the most complete fossil red panda specimens in the world allowed ecomorphological comparisons between the modern red panda, Ailurus fulgens …

Cranial Morphological Distinctiveness Between Ursus Arctos And U. Americanus, Benjamin James Hillesheim

Electronic Theses and Dissertations

Despite being separated by millions of years of evolution, black bears (Ursus americanus) and brown bears (Ursus arctos) can be difficult to distinguish based on skeletal and dental material alone. Complicating matters, some Late Pleistocene U. americanus are significantly larger in size than their modern relatives, obscuring the identification of the two bears. In the past, fossil bears have been identified based on differences in dental morphology or size. This study used geometric morphometrics to look at overall differences in cranial shape and used step-wise discriminant analysis to identify specific characters that distinguish cranial morphology between …

Quantifying And Simulating Fine-Scale Spatial Patterns In Plant Populations, Darin Schulte

Electronic Theses and Dissertations

Plant ecology as a discipline has increasingly acknowledged the importance of fine-scale spatial patterns in developing our understanding of community/population dynamics. These spatial patterns are largely determined by direct and indirect interactions between plants and their immediate neighbors. Such interactions thus play an important role in the structure and function of plant communities. Study of these types of local interactions has greatly benefitted from simulation based approaches. one such simulation method, agent-based modeling, has increasingly been identified as a useful tool for simulating these fine-scale interactions, and for investigating theoretical descriptions of underlying processes. Similarly, statistical techniques aimed at quantifying …

Human Dimensions Of Habitat Loss In The Plains And Prairie Potholes Ecoregion, Lily A. Sweikert

Electronic Theses and Dissertations

The Plains and Prairie Potholes Ecoregion (PPPE), is located in the north-central contiguous United States and is one of the most imperiled grassland regions in the world. Most of the region is privately owned and used for the production of agricultural commodities. In addition to its direct benefits to humanity, the PPPE provides multiple ecosystem services including, soil and water quality improvements, carbon sequestration, weather amelioration, and wildlife habitat. Recent increases in expansion of row crop agriculture concerns conservation practitioners about the long-term integrity of the PPPE. Conservation practitioners are looking to improve their private landowner conservation initiatives in the …