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Full-Text Articles in Life Sciences

Water Availability As A Cross-Scale Driver Of Microbial Functions And Free Viral Abundance In Soil, Aubrey K. Fine Dec 2022

Water Availability As A Cross-Scale Driver Of Microbial Functions And Free Viral Abundance In Soil, Aubrey K. Fine

Doctoral Dissertations

Viral infection is widespread in natural microbial communities, with extensive study in aquatic ecosystems demonstrating direct influence on host physiology, functional activity, and mortality. While similar dynamics are assumed to occur across ecosystems, soils are distinct microbial habitats where soil physiochemical structure and water availability constrain resource availability. These unique environmental conditions have been widely demonstrated to affect microbial distribution, diversity, and functional activity in bulk soil, while their influence on virus-microbe interactions and free viral abundance remains limited. To address this knowledge gap, this research had three broad aims: i) to investigate variability in microbial responses to drying-rewetting cycles …


Evaluating Current And Future Potential Distribution Of Epiphytic Orchids In The Congo Basin With Ecological Niche Models, Michael L. Ngoh Aug 2022

Evaluating Current And Future Potential Distribution Of Epiphytic Orchids In The Congo Basin With Ecological Niche Models, Michael L. Ngoh

Masters Theses

The Congo Basin Forest harbors a rich diversity of epiphytic communities, with the Orchidaceae alone making up more than 50% of all epiphytes in the region. Despite the huge diversity of epiphytes, many species, including epiphytic orchids, are at risk to a diverse array of threats. Climate change for instance poses severe threats to epiphytic orchids due to elevated temperatures, prolonged periods of droughts, as well as reduced rainfall across the Congo Basin Forest. In this study, we used ecological niche modeling and GIS techniques to identify spatial patterns of species richness, potential future climate refugia, and novel climatic suitability …


Climate-Driven Selection Results In Powerful Geographic Framework For Predicting Phenotype, Alexandra Neild May 2022

Climate-Driven Selection Results In Powerful Geographic Framework For Predicting Phenotype, Alexandra Neild

Masters Theses

Our ability to prepare for and mitigate the likely ecological and evolutionary impacts of climate change largely depends upon our ability to predict the phenotypic responses of organisms that allow them to persist, adapt, and migrate along environmental stress gradients. Using fifteen populations of cottonwoods, a dominant riparian forest tree, that are distributed along elevation gradients and represent three genetic provenances, we hypothesized and show that: 1) populations within a provenance demonstrate parallel evolutionary responses to climatic gradients associated with elevation; and 2) the evolutionary effects of elevation on bud-break phenology varied by provenance. Across all populations, we find strong …


Microbial Community Dynamics Of A Microcystis Bloom, Helena Pound Dec 2021

Microbial Community Dynamics Of A Microcystis Bloom, Helena Pound

Doctoral Dissertations

Harmful algal bloom events are notoriously associated with massive economic and environmental consequences, causing wildlife and human health risks. As these blooms increase in occurrence, duration, and severity around the world, it is essential to understand conditions leading to bloom formation and why they persist. Abiotic factors such as nutrients are commonly considered in bloom dynamics, but biotic interactions with co-occurring microbial species and viruses must also be taken into account. Harmful algal blooms dominated by the cyanobacterial genus Microcystis occur in bodies of water around the world and provide an ideal system in which to study top-down controls on …


Life History, Diet And Habitat Of The Federally Endangered Laurel Dace (Chrosomus Saylori), Shawna M. Fix May 2021

Life History, Diet And Habitat Of The Federally Endangered Laurel Dace (Chrosomus Saylori), Shawna M. Fix

Masters Theses

Laurel Dace (Chrosomus saylori) is a small, freshwater minnow that is endemic to headwater streams on Walden Ridge, Tennessee. The species was listed as federally endangered in 2011 and the U.S. Fish and Wildlife Service Recovery Plan indicates a need for life history, diet and habitat studies. A literature review, samples of archived specimens, and a surrogate species, the Tennessee Dace (Chrosomus tennesseensis), were used to describe the life history and diet of the Laurel Dace. A total of 370 Tennessee Dace were collected from Laurel Ford Branch, a stream 8.6 km from the Laurel Dace …


Root Phosphomonoesterase As A Vital Component Of Increasing Phosphorus Availability In Tropical Forests, Kristine Grace Manno Cabugao Dec 2020

Root Phosphomonoesterase As A Vital Component Of Increasing Phosphorus Availability In Tropical Forests, Kristine Grace Manno Cabugao

Doctoral Dissertations

Tropical forests, relative to other terrestrial ecosystems, exchange the largest amount of carbon with the atmosphere and also constitute a significant carbon sink. However, nutrient limitation, particularly of phosphorus (P), could limit growth of tropical forests and their function with the global carbon cycle. Thus, understanding root mechanisms to acquire P is necessary to representing the P cycle and corresponding interactions with plant growth. A large portion of total soil P in tropical forests occurs in organic forms, only accessible through root and microbial production of phosphatase enzymes. These phosphatase enzymes mineralize organic P into orthophosphate, the form of P …


Conservation Of Terrestrial Salamanders Through Hemlock Woolly Adelgid Management In Eastern Hemlock Forests Within Great Smoky Mountains National Park, Jonathan Lawrence Cox Dec 2020

Conservation Of Terrestrial Salamanders Through Hemlock Woolly Adelgid Management In Eastern Hemlock Forests Within Great Smoky Mountains National Park, Jonathan Lawrence Cox

Masters Theses

Hemlock woolly adelgid (Adelges tsugae; HWA), an invasive aphid-like arthropod, was first documented on the east coast of the United States in the 1950s. HWA is an herbivore which primarily feeds at the needle base of hemlock tree species (Pinaceae: Tsuga). With no evolutionary defenses and few biotic controls, the eastern and Carolina hemlock (Tsuga canadensis and Tsuga carolinensis) serve as the primary diet of HWA in eastern North America. The invasive pest began to spread rapidly throughout the hemlock’s range causing defoliation and death of the trees within 4 – 10 years. With the …


Carbon Metabolism In Cave Subaerial Biofilms, Victoria E. Frazier Dec 2020

Carbon Metabolism In Cave Subaerial Biofilms, Victoria E. Frazier

Masters Theses

Subaerial biofilms (SABs) grow at the interface between the atmosphere and rock surfaces in terrestrial and subterranean environments around the world. Multi-colored SABs colonizing relatively dry and nutrient-limited cave surfaces are known to contain microbes putatively involved in chemolithoautotrophic processes using inorganic carbon like carbon dioxide (CO2) or methane (CH4). However, the importance of CO2 and CH4 to SAB biomass production has not been quantified, the environmental conditions influencing biomass production and diversity have not been thoroughly evaluated, and stable carbon and nitrogen isotope compositions have yet to be determined from epigenic cave SABs. …


Biotic And Abiotic Drivers Of Plant Symbionts Determine Plant Performance, The Maintenance Of Diversity, And Response To Global Change, Jeremiah A. Henning May 2017

Biotic And Abiotic Drivers Of Plant Symbionts Determine Plant Performance, The Maintenance Of Diversity, And Response To Global Change, Jeremiah A. Henning

Doctoral Dissertations

Interactions among organisms regulate the structure and function of ecosystems and the response of ecosystems to global change. The outcome of species interactions is shaped by the partners involved in the interaction and the climate contexts of the systems in which they reside. Global change is altering the distributions of organisms as well as the climate contexts of the systems they reside within, shifting the biotic and abiotic factors shaping species interactions. Thus, predicting the response of ecosystem structure and function to global change remains unresolved. For my dissertation, I explored how the interactions among plants and their mutualistic communities …


Dispersal Rate Of The Asian Clam (Corbicula Fluminea): A Study With Pit Tagging, Tommy Cianciolo May 2017

Dispersal Rate Of The Asian Clam (Corbicula Fluminea): A Study With Pit Tagging, Tommy Cianciolo

Chancellor’s Honors Program Projects

No abstract provided.


Assessing The Functional Similarity Of Native And Invasive Anolis Lizards In The Food Webs Of Structurally-Simple Habitats In Florida, Nathan W. Turnbough Dec 2016

Assessing The Functional Similarity Of Native And Invasive Anolis Lizards In The Food Webs Of Structurally-Simple Habitats In Florida, Nathan W. Turnbough

Doctoral Dissertations

Invasive species often displace ecologically-similar native species, but the extent to which invading and displaced species function similarly in the food web processes of invaded communities is largely unknown. I investigated whether populations and individuals of an invasive Anolis lizard (the brown anole, Anolis sagrei) and the native congener it displaces in Florida (the green anole, Anolis carolinensis) are functionally equivalent in the food webs of open and structurally-simple habitats. In a system of invaded and uninvaded dredge-spoils islands, I found that both arthropod communities and winter bird communities covaried with brown anole abundance (and therefore the identity …


Individual Variation In Plant Traits Drives Species Interactions, Ecosystem Functioning, And Responses To Global Change, Quentin Daniel Read May 2016

Individual Variation In Plant Traits Drives Species Interactions, Ecosystem Functioning, And Responses To Global Change, Quentin Daniel Read

Doctoral Dissertations

Ecologists have long sought to understand the processes that lead to the riotous diversity in communities of organisms that inhabit disparate climates and landscapes. Such a diversity of traits leads to a diversity of interactions among species in natural communities, which in turn generates a diversity of potential responses to ongoing global change. In this dissertation, I do three things: I explore the forces that structure plant communities and the ecosystem functions that they mediate, I describe patterns of variation among communities, species, and individual organisms across environmental contexts, and I disentangle the direct effects of global change from the …


Environmental Controls On The Diversity And Distribution Of Endosymbionts Associated With Phacoides Pectinatus (Bivalvia: Lucinidae) From Shallow Mangrove And Seagrass Sediments, St. Lucie County, Florida, Thomas Walters Doty Dec 2015

Environmental Controls On The Diversity And Distribution Of Endosymbionts Associated With Phacoides Pectinatus (Bivalvia: Lucinidae) From Shallow Mangrove And Seagrass Sediments, St. Lucie County, Florida, Thomas Walters Doty

Masters Theses

Lucinid bivalves are capable of colonizing traditionally inhospitable shallow marine sediments due to metabolic functions of bacterial endosymbionts located within their gills. Because lucinids can often be the dominant sediment infauna, defining their roles in sediment and pore fluid geochemical cycling is necessary to address concerns related to changes in coastal biological diversity and to understanding the sensitivity of threatened coastal ecosystems over time. However, there has been limited research done to understand the diversity and distribution of many lucinid chemosymbiotic systems. Therefore, the goals of this thesis were to evaluate the distribution of Phacoides pectinatus and its endosymbiont communities …


Effects Of Forest Management Practices On Raccoon Ecology In A Longleaf Pine Ecosystem, Ronald Brian Kirby Dec 2015

Effects Of Forest Management Practices On Raccoon Ecology In A Longleaf Pine Ecosystem, Ronald Brian Kirby

Masters Theses

Raccoons (Procyon lotor) are ecological generalists common throughout a variety of habitats across their range. Although considered an economically important furbearer species in many regions, they are considered potentially important nest predators of certain species. Because raccoons may have a significant ecological impact on the landscape, it remains important to understand their ecology in a variety of ecosystems. We studied raccoon ecology in a longleaf pine ecosystem in southwestern Georgia, where little information for the species exists. Specifically, we assessed 269 daytime resting sites (i.e., refugia) associated with 31 radio-collared adult raccoons (18M, 13F) during 2014-2015 using an …


Evidence Of Late Quaternary Fires From Charcoal And Siliceous Aggregates In Lake Sediments In The Eastern U.S.A., Joanne P. Ballard Aug 2015

Evidence Of Late Quaternary Fires From Charcoal And Siliceous Aggregates In Lake Sediments In The Eastern U.S.A., Joanne P. Ballard

Doctoral Dissertations

The late-glacial transition to the Holocene, 15,000–11,600 cal yr BP, is an enigmatic period of dynamic global changes and a major extinction event in North America. Fire is an agent of disturbance that transforms the environment physically and chemically, and affects plant community composition. To improve understanding of the linkages between fire, vegetation, and climate over the late glacial and Holocene in the eastern U.S., I analyzed lake-sediment cores for charcoal and indicators of wood ash, and compared results to existing pollen records. A new microscopic charcoal record from Anderson Pond, Tennessee revealed high fire activity from 23,000–15,000 cal yr …


Survival And Growth Rate Of Translocated Freshwater Mussels Lampsilis Fasciola And Medionidus Conradicus, Laura L. Pullum Aug 2015

Survival And Growth Rate Of Translocated Freshwater Mussels Lampsilis Fasciola And Medionidus Conradicus, Laura L. Pullum

Masters Theses

Freshwater mussels (Family Unionidae and Margaritiferidae) are a widely threatened group of bivalve molluscs, particularly in the Southeastern United States. Translocation of freshwater mussels is an increasingly common conservation method. However, there are relatively few studies that quantitatively investigate the factors influencing translocation success or failure. In October 2013, hundreds of Medionidus conradicus and Lampsilis fasciola were translocated to the Pigeon and Nolichucky Rivers in Tennessee, with an interim partial survey (June 2014) and a full survey (October 2014). In this study, I analyze this field-collected data to determine the mechanism(s) that currently influence the outcomes of Tennessee mussel translocation. …


Bats And Disease: Behavioral And Community Responses Of Southern Bat Populations During The White-Nose Syndrome Epizootic, Riley Fehr Bernard May 2015

Bats And Disease: Behavioral And Community Responses Of Southern Bat Populations During The White-Nose Syndrome Epizootic, Riley Fehr Bernard

Doctoral Dissertations

This dissertation investigates regional differences in the behavior and activity of bats in eastern North America during the white-nose syndrome epizootic, specifically in the understudied region of the Southeastern United States. An introductory section provides a brief review of the history of white-nose syndrome, an emerging infectious disease in bats, and its introduction into North America. Chapter one provides the first documented evidence of bat activity outside of hibernacula throughout winter. The research presented in chapter two attempts to explain the variation in load and prevalence of P. destructans among species, sites and between years. Finally, chapter three examines the …


Influence Of Habitat Manipulations On Northern Bobwhite Resource Selection On A Reclaimed Surface Mine, Jarred Milford Brooke May 2015

Influence Of Habitat Manipulations On Northern Bobwhite Resource Selection On A Reclaimed Surface Mine, Jarred Milford Brooke

Masters Theses

Northern bobwhite populations have declined range-wide over the past 40 years. The intensification of agriculture, conversion of pastures to nonnative cool-season grasses, advanced succession, and urbanization have resulted in the deterioration and elimination of bobwhite habitat. Recent conservation efforts have called for a landscape-level approach to the conservation of northern bobwhite populations. However, identifying large areas to manage bobwhite populations is problematic. Reclaimed mine lands offer an opportunity to manage large contiguous tracts of early successional vegetation to conserve northern bobwhite populations. We studied northern bobwhite resource selection throughout the year from August 2009 to March 2014. We investigated the …


Habitat Use And Response To Wetland Management Practices Of Non-Breeding Dabbling Ducks In Western Tennessee, Matthew Doddridge Mcclanahan May 2015

Habitat Use And Response To Wetland Management Practices Of Non-Breeding Dabbling Ducks In Western Tennessee, Matthew Doddridge Mcclanahan

Masters Theses

Western Tennessee is an important area for non-breeding waterfowl in the Mississippi Flyway, including over 40% of the Mississippi Flyway population of American black ducks (Anas rubripes, hereafter black ducks), a species in decline. Information is lacking on waterfowl community ecology in the region, and managers must identify key habitats and consider functional use and potential predictors of resource use by non-breeding communities. Impacts of wetland management practices, such as moist-soil disking and subsequent planting of desirable grasses (i.e., Japanese millet [Echinochloa frumentacea], hereafter millet), must also be tested relative to impacts on waterfowl use and …


Impacts Of Climate Change, Human Land Use, And Mercury Contamination On Southern Appalachian Plethodontid Salamanders, Michael Kevin Hamed Aug 2014

Impacts Of Climate Change, Human Land Use, And Mercury Contamination On Southern Appalachian Plethodontid Salamanders, Michael Kevin Hamed

Doctoral Dissertations

The Southern Appalachian Mountains are home to the greatest diversity of Plethodontid Salamanders in the world. The future for these salamanders is uncertain as globally amphibians have been experiencing significant population declines. We investigated the impact of habitat loss, chemical contaminants, and climate change on Plethodontid salamanders in northeastern Tennessee and southwestern Virginia. Four-toed salamanders (Hemidactylium scutatum) were negatively impacted by powerline right-of-way (ROW) mowing. Embryonic and larval survival significantly decreased in ROW after mowing and required up to 3 years of vegetation regrowth to reach post mowing survival. We also investigated mercury contamination in black-bellied salamanders ( …


Habitat Selection And Partitioning Among Darters In Two Tributaries Of The Clinch River, And Stream Restoration Effects On Substrate Profile, Daniel James Walker May 2014

Habitat Selection And Partitioning Among Darters In Two Tributaries Of The Clinch River, And Stream Restoration Effects On Substrate Profile, Daniel James Walker

Masters Theses

The group of fish referred to as darters is extremely biodiverse. Often, several closely related species will inhabit the same areas of streams, and prior research has investigated how these species may be partitioning the resources in low-order streams in which they are sympatric. The habitat partitioning of darters in two streams in the Clinch River system, Coal and Cove Creeks, was investigated. The study sites were picked due to their involvement in both physical and biological stream restoration efforts within the last several years, including the collection, translocation, and reintroduction of rainbow darters (Etheostoma caeruleum) from reference sites in …


Freshwater Mussels (Bivalvia: Margaritiferidae And Unionidae) Of The Buffalo River Drainage, Tennessee, Matthew Philip Reed May 2014

Freshwater Mussels (Bivalvia: Margaritiferidae And Unionidae) Of The Buffalo River Drainage, Tennessee, Matthew Philip Reed

Masters Theses

The Buffalo River in Tennessee once hosted a rich population of freshwater mussels. During the 1980s, monitoring efforts demonstrated evidence of drastic declines and extirpation of entire assemblages. Increases in municipal development in the headwater tributaries and agriculture in the main stem of the Buffalo River are suspected causes for mussel community declines throughout the river. In 2011, collection data documented evidence of recovery in the lower Buffalo River. The aims of this project were: 1) to update the status, distribution, and species composition of mussels in the Buffalo River and its major tributaries through qualitative sampling, and 2) to …


Wood Decomposition In A Warmer World, Emily Elizabeth Austin Dec 2013

Wood Decomposition In A Warmer World, Emily Elizabeth Austin

Doctoral Dissertations

Climatic warming is altering species distributions and ecosystem functions across the globe. Wood is an important carbon pool and the fungal communities in wood are relatively simple compared to those in soil. These factors make decomposing wood an ideal system for exploring the influence of decomposer community on the response of decomposition to warming. My research has focused on the effects of warming wood decomposition rates and wood decomposing communities. Using field and lab- based manipulative experiments and field observations I explore the influence of tree species, wood decomposition stage, geography and warming on fungal community structure and activity. In …


Population Demographics And Genetic Structure Of Black Bears In Coastal Louisiana, Jesse Charles Troxler Dec 2013

Population Demographics And Genetic Structure Of Black Bears In Coastal Louisiana, Jesse Charles Troxler

Masters Theses

The range and abundance of the Louisiana black bear (Ursus americanus luteolus) were greatly diminished during the 20th century. This subspecies was reduced to 3 small, isolated subpopulations in Louisiana as bottomland hardwood habitat was converted to agriculture. These bears were listed as threatened by the U.S. Fish and Wildlife Service in 1992 and a recovery plan was published in 1995. Recovery requires estimates of population parameters to evaluate current population status and future viability. I conducted a mark-recapture study from 2010 to 2012 to estimate demographic parameters of the coastal population of Louisiana black bears. Because inbreeding …


Prevalence And Transmission Potential Of Borrelia Burgdorferi In Three Species Of Wildcaught Plestiodon Spp. Skinks Of The Southeastern United States, Teresa Dianne Moody Aug 2013

Prevalence And Transmission Potential Of Borrelia Burgdorferi In Three Species Of Wildcaught Plestiodon Spp. Skinks Of The Southeastern United States, Teresa Dianne Moody

Masters Theses

In the southeastern United States, blue-tailed skinks (Plestiodon spp.) are important hosts for Ixodes scapularis ticks, the principal vector of Lyme disease (LD) in this region. Skinks and other southeastern lizards are not thought to be reservoir competent for Borrelia burgdorferi sensu stricto (Bbss), the etiological agent of LD in the United States. . Lizard-feeding by southeastern I. scapularis may tend to suppress sylvatic cycles of B. burgdorferi, and thus may be an important reason why LD case rates in the Southeast are much lower than in the Northeast and upper Midwest. Nevertheless, some skinks …


Ant Community Dynamics And The Effects Of Global Warming, Katharine Lisa Stuble May 2013

Ant Community Dynamics And The Effects Of Global Warming, Katharine Lisa Stuble

Doctoral Dissertations

This dissertation seeks to provide an understanding of how species coexist and, further, how climate change may alter communities by acting on the mechanisms that promote coexistence. Specifically, I examined coexistence among ant species in eastern deciduous forests and the effects that warming may have on foraging activity. Through a series of field observations, I sought evidence for the importance of four of the most commonly cited mechanisms for coexistence among ant species: the dominance – discovery tradeoff, the dominance – thermal tolerance tradeoff, spatial segregation, and niche partitioning. In this system, I did not find evidence for any of …


Soil Microbial Community Succession During Cadaver Decomposition, Kelly Lynn Cobaugh May 2013

Soil Microbial Community Succession During Cadaver Decomposition, Kelly Lynn Cobaugh

Masters Theses

Microbes play critical roles in nutrient cycling in terrestrial ecosystems. In particular, microbial decomposition of organic matter is a key step in carbon and nutrient cycling, linking above-ground and below-ground pools. It is well known that the microbial community changes in structure and function following the introduction of organic matter into a terrestrial system. The decomposition of plant litter has been extensively investigated but the decomposition of animal-derived organic matter has often been overlooked. The unique characteristics of animal input are hypothesized to dictate a distinct decomposition process. This study examined the microbial community responsible for decomposition of animal-derived organic …


Vegetation Response To Oak Savanna And Woodland Restoration In The Mid-South Usa, Andrew Lee Vander Yacht May 2013

Vegetation Response To Oak Savanna And Woodland Restoration In The Mid-South Usa, Andrew Lee Vander Yacht

Masters Theses

The decline and degradation of oak savanna and woodland communities throughout the Mid-South underscores the need to develop management techniques capable of their efficient and successful restoration. Therefore, my objectives for this work were to document plant community response to variations in canopy disturbance level, fire seasonality, and herbicide control of hardwood midstories. In Chapter One, I provide a thorough review of the current body of knowledge concerning open-oak communities and their restoration, with specific focus on herbaceous and woody plant response to canopy disturbance, fire, and herbicide midstory management. Chapter Two details the response of herbaceous and woody vegetation …


On Global Change, Direct And Indirect Interactions, And The Structure Of Ecological Communities: Theoretical And Empirical Tests, Mariano Alberto Rodriguez Cabal Dec 2012

On Global Change, Direct And Indirect Interactions, And The Structure Of Ecological Communities: Theoretical And Empirical Tests, Mariano Alberto Rodriguez Cabal

Doctoral Dissertations

Human induced global change (climate change, CO2 enrichment, nitrogen deposition, habitat degradation and biological invasions) is the most serious threat to biodiversity. Understanding how ecosystems will respond to different components of global change, and how these responses will affect key ecological processes, has become essential in contemporary ecology. For example, several studies have shown that exotic invasive species have negative impacts on the composition of communities, habitat structure and ecosystem processes. Particularly, exotic species may have negative effects on species interactions due to local extinctions, competition and/or replacement of interactions. Despite the large body of research demonstrating the negative …


The Impacts Of Surface Mining Restoration Efforts On Soil Dwelling Nematode Communities In The Appalachian Region, Haley Shae Smith Dec 2012

The Impacts Of Surface Mining Restoration Efforts On Soil Dwelling Nematode Communities In The Appalachian Region, Haley Shae Smith

Masters Theses

Traditional restoration of post mining sites in the southeastern U.S. utilizes methods that discourage above and below-ground succession of native floral and faunal communities. Recent advances in mining restoration techniques proposed by the Appalachian Regional Reforestation Initiative (ARRI) have improved above-ground plant succession and growth rates in reclaimed sites by developing the Forestry Reclamation Approach (FRA), a process that discourages substrate compaction and encourages native plant succession. The below-ground component of these reclaimed areas remains undescribed, however. Below-ground invertebrate communities in mining restoration sites have been largely ignored, despite their potential importance to the long-term recovery of these profoundly disturbed …