Life Sciences Commons^™

An Experimental Study Of Juvenile Competition And Habitat Niche Partitioning Between A Native Lizard (Anolis Carolinensis) And An Introduced Congener (Anolis Sagrei) In The Southeastern United States, Justin W. Walguarnery

Doctoral Dissertations

Since its introduction to Florida, the brown anole, Anolis sagrei, has steadily expanded its range into that of its native congener in the southeastern United States, the green anole, A. carolinensis. Anolis sagrei achieves very high densities both in its native and invaded range and appears to impose population declines and shifts in the realized habitat niche of A. carolinensis. In order to investigate whether these effects arise prior to the adult age class in which they have previously been described, I studied the behavior of juvenile anoles at the individual, dyadic, and neighborhood levels. Contrary to some …

Forest Responses To Rising Atmospheric Co2: Causes And Consequences Of Increased Fine-Root Production In A Co2-Enriched Sweetgum Plantation, Colleen Marie Iversen

Doctoral Dissertations

Increased forest growth in response to rising atmospheric concentrations of CO₂ may mitigate a portion of fossil fuel emissions, especially if carbon is sequestered in longlived biomass or soil pools. Greater carbon uptake under elevated atmospheric [CO₂] in forested ecosystems may facilitate the production of small diameter (i.e. “fine”) roots used for nutrient acquisition. Increased fine-root production in forested ecosystems may affect soil carbon storage and nitrogen cycling because fine roots live and die in the span of a year. My dissertation research took advantage of a long-term, on-going Free-Air CO₂-Enrichment experiment in a sweetgum …

Phenotypic And Genetic Correlations Among Mating Traits In Three Species Of Nasonia (Hymenoptera: Pteromalidae, Jason E. Leonard

Doctoral Dissertations

Phenotypic correlations between traits are thought to reflect genetic correlations. However, traits related to a central function, like reproduction, need not all be genetically correlated. Identifying genetic correlations between behavioral traits can help identify the evolutionary relationship between different behaviors, as well as provide initial information on the number of genes involved in behavioral variation and the rates and direction of evolution. This body of work describes the phenotypic and genetic relationship between mating traits in the parasitoid wasp genus Nasonia. Chapters 2 and 3 describe behavioral differences among the three species of Nasonia. Two of the species, …

Community Invasibility: From Pattern To Process Across Multiple Spatial Scales In An Old-Field Ecosystem, Lara A. Souza

Doctoral Dissertations

Biological invasions threaten biodiversity, and understanding the factors that influence a community’s susceptibility to invasion informs both management of invasive species and conservation of biodiversity. The biotic resistance hypothesis postulates that communities with greater number of competitors, predators and/or pathogens will resist biological invasions. The underlying mechanism of biotic resistance, in the realm of competition, is that in species-rich communities harbor fewer open niches for introduced species to colonize therefore decreasing the probability of invasion. My dissertation research evaluated the role of native species diversity, as well as other biotic, abiotic and landscape factors shaping exotic species richness at multiple …

Distribution And Dynamics Of Pyrene-Degrading Mycobacteria In Freshwater Sediments Contaminated With Polycyclic Aromatic Hydrocarbons, Jennifer M. Debruyn

Doctoral Dissertations

Microbial biodegradation of polycyclic aromatic hydrocarbons (PAHs) is the primary means of attenuation of these toxic and carcinogenic compounds from contaminated soils and sediments. The documented toxicity and carcinogenicity of many PAHs demands remedial action for PAH-contaminated soils and sediments. This is especially important for historically contaminated sites, where higher molecular weight PAHs (HMW) are recalcitrant. Recently, fast-growing Mycobacteria have been identified that can degrade HMW PAHs, such as pyrene and benzo[a]pyrene. These bacteria have been isolated from a variety of geographical locations, indicating a cosmopolitan distribution.

This dissertation work was driven by the need for a better understanding of …

Effects Of Environmental Heterogeneity In A Host-Parasite Coevolutionary Chase, Barry D. Derennaux

Masters Theses

Species-species interactions are ubiquitous and it is thought that selection is very strong in many of these interactions, resulting in reciprocal evolution by natural selection. In antagonistic coevolution, one species benefits at the cost of another, resulting in a system where selection favors the strengthening of the interaction in one species, and acts to reduce the interaction in the other species. Previous theoretical work in homogeneous systems has identified a wide range of possible behaviors (including limit cycles, heteroclinic cycles, and equilibria) as well as explored how parameters effect local adaptation in species. Here we explore how heterogeneous systems and …

The Effects Of Treefall Gap Disturbances On Litter Ant Assemblages In A Tropical Montane Cloud Forest, Margaret Patrick

Masters Theses

In this study, we considered the effects of treefall gap disturbances on leaf litter ant assemblages in a Neotropical montane cloud forest. We asked a series of questions: (1) Do species richness, number of workers, and assemblage composition of leaf litter ants differ between treefall gaps and adjacent intact forests? (2) Do leaf litter ant assemblages become more similar to the assemblages in adjacent forest as gaps age? (3) What abiotic and biotic factors are correlated with ant species richness, and does the relative importance of these factors differ between gap and intact forest sites? To address these questions we …

Temporal Change Within And Among Forest Communities Of Great Smoky Mountains National Park: The Influence Of Historic Disturbance And Environmental Gradients, Windy A. Bunn

Masters Theses

Understanding how ecological communities change over time is critical for biodiversity conservation. However, few long-term studies directly address decadal-scale changes in the ecological communities of protected areas. In this study, we take advantage of a network of permanent forest plots, established in Great Smoky Mountains National Park in 1978, to investigate temporal changes in plant communities. In particular, we examine the factors that influence temporal change in species richness and composition within communities and temporal change in compositional similarity among communities. In 2007, we revisited 15 permanent plots that were logged in the late 1920s and 15 permanent plots that …

Experiments On Multiple Factors Affecting Pinaceae Invasions On Isla Victoria, Nahuel Huapi National Park, Argentina, Martin Andres Nuñez

Doctoral Dissertations

Invasive species are one of the greatest threats to global biodiversity. Therefore, to conserve biodiversity and manage exotic species effectively, it is crucial to determine the factors that regulate biological invasions. Historically, the study of invasions has focused on the dynamics and characteristics of successful invasive species. While studying successful invaders has enhanced our understanding of biological invasions, studying the failures can also illuminate the factors that limit invasions. To further understand the factors limiting the spread of exotic species, I studied invasion dynamics of several species in the family Pinaceae on Isla Victoria, Argentina. Approximately 80 years ago, thousands …

Systematics Of Gratiola (Plantaginaceae), Larry D. Estes

Doctoral Dissertations

Gratiola (Plantaginaceae tribe Gratioleae) is a genus of ca. 33 wetland-adapted herbaceous species found mostly in temperate or tropical-montane regions of the Americas, Eurasia, and Australasia. The only worldwide taxonomic treatment of Gratiola was published more than 160 years ago and only a few representatives of the genus have been included in published molecular phylogenetic studies. The overall aim of this investigation was to provide a modern systematic study of Gratiola by determining the phylogenetic placement of Gratiola within the Gratioleae using chloroplast DNA sequence data (Chapter 2); examining the phylogenetic relationships, morphological character evolution, and biogeographical patterns within Gratiola …

Biological Invasions, Global Climate Change And Species Distribution Models: An Investigation Of Species-Climate Relationships Across Space And Time, Matthew C. Fitzpatrick

Doctoral Dissertations

Species distribution models are increasingly being applied to questions in ecology, biogeography and evolution, and in particular to the problem of predicting the potential spread of invasive species and the potential impacts of climatic change on biodiversity. However, despite their broad application, several conceptual limitations still preclude the use of species distribution models in many theoretical and practical applications. Chief among these is the assumption that climate alone determines the geographic ranges of species, as opposed to biotic interactions and dispersal limitations, and that such species-climate relationships remain largely unchanged across space and time. In this context, I explore the …

The Effects Of Prey Abundance And Bt (Bacillus Thuringiensis) Crops On Bat Activity In South-Central Texas Agroecosystems, Kimberly S. Kennard

Masters Theses

Agroecosystems produce insects in great abundance, with episodic irruptions in time, and patchy distributions in space. In the industrial scale agroecosystems of south-central Texas, millions of Brazilian free-tailed bats (Tadarida brasiliensis) consume these insect pests. In the past decade, growers in Texas have planted transgenic Bt (Bacillus thuringiensis) crops on a large scale, which may reduce populations of target insect species by up to 95%. To investigate potential impacts of this evolving agricultural landscape on insectivorous bats, I examined the response of foraging bats to emergences of insects from replicate Bt and non-Bt fields of corn and cotton in the …

Hybridization Produces Novelty When The Mapping Of Form To Function Is Many To One, Nicholas F. Parnell, C Darrin Hulsey, J. Todd Streelman

Faculty Publications and Other Works -- General Biology

Background

Evolutionary biologists want to explain the origin of novel features and functions. Two recent but separate lines of research address this question. The first describes one possible outcome of hybridization, called transgressive segregation, where hybrid offspring exhibit trait distributions outside of the parental range. The second considers the explicit mapping of form to function and illustrates manifold paths to similar function (called many to one mapping, MTOM) when the relationship between the two is complex. Under this scenario, functional novelty may be a product of the number of ways to elicit a functional outcome (i.e., the degree of MTOM). …