Other Ecology and Evolutionary Biology Commons^™

Climatic Range Filling Of North American Trees, Benjamin Seliger

Electronic Theses and Dissertations

Understanding the degree to which species distributions are controlled by climate is crucial for forecasting biodiversity responses to climate change. Climatic equilibrium, when species are found in all places which are climatically suitable, is a fundamental assumption of species distribution models, but there is evidence in support of climate disequilibria in species ranges. Long-lived, sessile organisms such as trees may be especially vulnerable to being outpaced by climate change, and thus prone to disequilibrium. In this dissertation, I tested the degree to which North American trees are in equilibrium with their potential climatic ranges using the ‘range filling’ metric, which …

Drivers Of Tree Growth And Mortality In An Uneven-Aged, Mixed-Species Conifer Forest Of Northeastern United States, Erin Fien

Electronic Theses and Dissertations

Individual tree growth and mortality drive forest stand dynamics and are important, universal metrics of tree success. Studying the factors that affect growth and mortality is particularly challenging in mixed-species, uneven-aged systems due to their defining heterogeneity and strong temporal and spatial variability. However a better understanding of the factors driving growth and mortality in mixed-species, uneven-aged forest is crucial to managing and maintaining these valuable systems for the future.

The goal of this study was to determine the relative importance of individual tree attributes (e.g., species, size, neighborhood crowding, crown position) and environmental characteristics (e.g., soil moisture) in driving …

Breeding Bird Response To Post Oak Savanna Restoration Seven Years Post Management In Eastern Texas, Courtney Mcinnerney

Electronic Theses and Dissertations

Oak savannas were once an abundant vegetation type in the Midwestern United States that have now declined to <1% of their original distribution. Historically, natural disturbances such as periodic fire and grazing maintained oak savannas, but these have been reduced or eliminated, resulting in woody encroachment and subsequent habitat loss and degradation. In 2009-10, a baseline, pre-restoration study was completed to determine vegetation characteristics, breeding bird abundances, nest success, and nest site selection at the Gus Engeling Wildlife Management Area (GEWMA) in eastern Texas. The results showed a lack of savanna vegetation structure on degraded sites and few savanna or grassland obligate bird species. The goal of this study was to determine how breeding birds of oak savanna vegetation types in eastern Texas respond to restoration effects 7 years after initial management. Post-restoration surveys completed in 2016-17 showed a change in avian assemblages from a more woodland dominated community to grassland/savanna community. The presence and breeding of savanna obligate species dickcissel (Spiza americana) and lark sparrow (Chondestes grammacus) indicates that the restoration was successful. The presence of savanna species can be linked to the herbaceous vegetation that was restored to more closely resemble historic oak savanna structure and can quantify the success of restoration efforts.

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 …

Dead Wood And Decomposition In A Tropical Forest : Vertical Patterns, Long-Term Processes, And The Role Of Lightning., Evan Matthew Gora

Electronic Theses and Dissertations

This dissertation investigates the distribution, production, and decomposition of dead wood (or woody debris) in a lowland tropical forest within the Barro Colorado Nature Monument in Panama. Although the importance of woody debris is widely accepted, information describing components of WD pools and fluxes is generally separated in both time and space, particularly in understudied tropical forests. Here I provide a comprehensive inventory of woody debris in a lowland tropical forest (Chapter 1). Woody debris is highly aggregated and difficult to quantify, and this study demonstrates that historic estimates of woody debris pools and fluxes underestimate their uncertainty. In a …

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 …

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 …

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 …

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, …

Environmental Factors Affecting Hatch Success In The Loggerhead Sea Turtle (Caretta Caretta), Mattie J. Whitesell

Electronic Theses and Dissertations

The loggerhead turtle (Caretta caretta) is a species federally listed as “threatened” whose global populations are declining. Georgia Department of Natural Resources conservation protocols for this species require the daily monitoring of nesting activity and permit physical relocation of nests which are at risk of being eroded or flooded by storms and high tides in order to increase hatch success--the proportion of hatched to unhatched eggs. Relocated nests are moved to an area with higher elevation in order to avoid flooding, but other variables such as increased temperature and decreased moisture are introduced when relocating. For years temperature …