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Articles 1 - 15 of 15
Full-Text Articles in Biology
The Old Family Clock: Exploring High Variation Of Chronotype In The Common House Spider, Parasteatoda Tepidariorum, Caitlin Jones
The Old Family Clock: Exploring High Variation Of Chronotype In The Common House Spider, Parasteatoda Tepidariorum, Caitlin Jones
Electronic Theses and Dissertations
Circadian rhythms are often tightly confined around a mean of 24 hours with little variation in traditional model organisms in the absence of environmental time cues. Some spider species fall well outside this normal range with mean periods of 18 hours and variation around these means of 6 hours or more. This extreme variation in circadian rhythm is not well-understood and is the focus of the current study. Using Parasteatoda tepidariorum as a model organism, we investigated whether variation in eight circadian parameters could be explained by genetic variability, environmental conditions, or an endogenous feature of the circadian system of …
Importance Of The Microhabitat And Microclimate Conditions In The Northern Gray-Cheeked Salamander (Plethodon Montanus) Across An Elevation Gradient, Trevor Chapman
Electronic Theses and Dissertations
The southern Appalachian Mountains have among the highest salamander diversity in the world, largely due to local speciation in the family Plethodontidae. Plethodontid salamanders (i.e., lungless salamanders) are particularly sensitive to habitat climate conditions due to their reliance on cutaneous respiration, and their immediate environmental conditions (microhabitat) likely influence their dispersion and activity more than the large-scale atmospheric conditions. The Northern Gray-cheeked salamander (Plethodon montanus) is restricted to high elevations in the Appalachian Mountains. Our goal was to investigate the relationship between P. montanus and its microhabitat by examining behavioral preference for climatic conditions, characterizing the microclimate with …
Fish Community Assembly At Multiple Spatial Scales In East Texas Streams, Jake R. Swanson
Fish Community Assembly At Multiple Spatial Scales In East Texas Streams, Jake R. Swanson
Electronic Theses and Dissertations
Stream communities are structured by environmental processes that vary in strength across different spatiotemporal scales. Therefore, revealing how stream fish communities are influenced by environmental gradients may clarify how communities respond to disturbance associated with anthropogenic change. I investigated the relative role environmental variables play in the processes that structure the taxonomic and functional diversity of stream fish communities, as well as historical trends in occurrence and local habitat associated with a species of greatest conservation need within east Texas. The results of this study indicate that stream sites with more habitat complexity and stability support a more taxonomically and …
Environmental Gradients Impact Key Leaf Traits In Riparian Trees, Amanda Malone
Environmental Gradients Impact Key Leaf Traits In Riparian Trees, Amanda Malone
Electronic Theses and Dissertations
Specific leaf area (SLA) reflects a plant’s carbon investment per area and relates to generalized leaf economics spectrum growth strategies (LES). To fill gaps of knowledge about intraspecific SLA variation and why it is often inconsistent with the LES, we studied the response of two riparian tree species along the urban-rural gradient in Northeastern Colorado: an invasive, nitrogen-fixer with broad tolerances and a nitrogen-limited and shade-intolerant native. Despite these differences, the two species responded similarly, apart from the response to the urban-rural gradient, in which lower nitrogen in rural areas was associated with a more conservative strategy in the native …
Understanding Patterns And Functional Impacts Of An Invasive Tree And Its Biological Control In A Riparian System, Annie L. Henry
Understanding Patterns And Functional Impacts Of An Invasive Tree And Its Biological Control In A Riparian System, Annie L. Henry
Electronic Theses and Dissertations
Invasive species have become an inextricable part of the landscape, particularly in riparian plant communities, and removal is often a key component of restoration programs. Biological control (biocontrol) is a method of removal that is often both efficient and effective. However, the impact of biocontrol on target species and indirect effects from invasive species removal can be hard to predict. While monitoring the impact of invasive species removal usually involves some species-based assessment such as changes in diversity, historically dominant species or native species, these strategies do not typically provide insight into the mechanisms underlying plant community response to removal. …
Chronoecology Of A Cave-Dwelling Orb-Weaver Spider, Meta Ovalis (Araneae: Tetragnathidae), Rebecca Steele
Chronoecology Of A Cave-Dwelling Orb-Weaver Spider, Meta Ovalis (Araneae: Tetragnathidae), Rebecca Steele
Electronic Theses and Dissertations
Circadian clocks enable coordination of essential biological and metabolic processes in relation to the 24-hour light cycle. However, there are many habitats that are not subject to this light cycle, such as the deep sea, arctic regions, and cave systems. This study analyzes the circadian pattern of isolated populations of a subterranean spider, Meta ovalis from two Tennessee caves and five Indiana caves. Locomotor activity was recorded with TriKinetics LAM50 Locomotor Activity Monitor under a 12-hour light (L), 12-hour dark (D) (LD 12:12) cycle preceding total darkness (DD). Significant differences were found within and among populations found in Tennessee cave …
Predator-Based Selection And The Impact Of Edge Sympatry On Components Of Coralsnake Mimicry, Lauren E. Wilson
Predator-Based Selection And The Impact Of Edge Sympatry On Components Of Coralsnake Mimicry, Lauren E. Wilson
Electronic Theses and Dissertations
Studying warning coloration and mimicry is an effective way to understand predator-driven selection and phenotypic diversity. The presence (sympatry) or absence (allopatry) of a toxic model plays a role in shaping mimetic phenotypes. However, the impact of edge sympatry and allopatry on predation of mimetic phenotypes is not well understood. We studied coralsnake mimicry to test how edge sympatry and allopatry affect predation on mimetic phenotypes. Specifically, we tested 1) if overall attack rates varied with edge sympatry of coralsnakes 2) which color patterns conferred a fitness advantage 3) which specific mimetic signal components are important in driving predatory attacks …
Plasticity And The Impact Of Increasing Temperature On A Tropical Ectotherm, Adam A. Rosso
Plasticity And The Impact Of Increasing Temperature On A Tropical Ectotherm, Adam A. Rosso
Electronic Theses and Dissertations
Organisms may respond to climate change through behavior, genetic adaptation, and/or phenotypic plasticity. Tropical ectotherms are thought to be especially vulnerable to climate change because most have a narrow range of thermal tolerance while living close to their upper thermal tolerance limits. Additionally, many tropical species live in closed-canopy forests, which provide homogenous thermal landscapes that prevent behavioral compensation for stressfully warm temperatures. Finally, tropical ectotherms are thought to have decreased capacity for phenotypic plasticity because they have evolved in thermally stable environments. We tested gene expression patterns and phenotypic plasticity in the Panamanian slender anole by a) measuring changes …
Microplastics In The Digestive System Of The Atlantic Sharpnose Shark (Rhizoprionodon Terraenovae) In Winyah Bay, Sc, Elise Virginia Pullen
Microplastics In The Digestive System Of The Atlantic Sharpnose Shark (Rhizoprionodon Terraenovae) In Winyah Bay, Sc, Elise Virginia Pullen
Electronic Theses and Dissertations
The digestive tracts and livers of adult male Atlantic sharpnose sharks (N=16), Rhizoprionodon terraenovae, from Winyah Bay, South Carolina were examined for ingested microplastics. R. terraenovae is a small, locally abundant, coastal mesopredatory elasmobranch belonging to the family Carcharhinidae. Microfibers comprised the largest categories of plastics (94% of the total), and were found in 100% of sharks examined. The number of micro- and other plastics ranged from 34 to 75 per individual and totaled 927. The majority of plastics (40%) were blue in coloration, and 55% were <1 mm in length. Microplastics were observed on both the interior and exterior of the organs examined, and three microfibers were embedded within the stomach lining, an observation not previously reported in marine vertebrates and one which represents a potential pathway for the translocation of ingested microplastics.
Differentiating Black Bears (Ursus Americanus) And Brown Bears (U. Arctos) Using Linear Tooth Measurements And Identification Of Ursids From Oregon Caves National Monument, Emily Bogner
Electronic Theses and Dissertations
North American black bears and brown bears can be difficult to distinguish in the fossil record due to similar dental and skeletal morphologies. Challenges identifying ursid material from Oregon Caves National Monument (ORCA) called for an accurate tool to distinguish the species. This study utilized a large database of lower tooth lengths and ratios in an attempt to differentiate black and brown bears in North America. Further, this project examined how these linear measurements differ geographically. Analysis of variance (ANOVA) found significant differences between black and brown bears from across North America for every variable studied. Stepwise discriminant analyses (DA) …
Tidal Creek And Substrate Effects On Oyster Reef Associated Fish And Decapod Condition And Density, Thomas S. Funk
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 …
Measuring Fertilization In Populations Of Sea Scallop (Placopecten Magellanicus): Developing And Testing Methods In The Laboratory And Field, Skylar Bayer
Electronic Theses and Dissertations
Most marine organisms are broadcast spawners, releasing their sperm and eggs into the water column. Methods of measuring in situ fertilization have proven successful with a few model species, which are reviewed in my introductory chapter. However, many commercially exploited species, such as the sea scallop Placopecten magellanicus, have been neglected. Sea scallop populations have greatly increased from fishing closures, but the mechanism behind this response is uncertain, particularly in regard to fertilization. In this dissertation I developed a methodology of measuring fertilization success and spawning events of P. magellanicus, tested it in laboratory and field settings, and …
Sources Of Ecologically Important Trait Variation In Mosquitofish (Gambusia Affinis And Gambusia Holbrooki), Heather Ann Arnett
Sources Of Ecologically Important Trait Variation In Mosquitofish (Gambusia Affinis And Gambusia Holbrooki), Heather Ann Arnett
Electronic Theses and Dissertations
The study of contemporary evolution and eco-evolutionary dynamics is classically defined in terms of genetic evolution, but the actual suite of processes driving contemporary trait change is likely much more complex than often credited. This dissertation considers additional mechanisms of trait change that might be important to an emerging model system for study of contemporary evolution and eco-evolutionary dynamics. Specifically, the research focuses on phenotypically plastic and demographic trait variation in Eastern and Western Mosquitofish (Gambusia affinis and G. holbrooki) facing the major ecological gradient of predation risk. Plasticity experiments employed a common-garden rearing design to manipulate fish …
Tidal Influences On Bacterial And Phytoplankton Abundances And The Resulting Effects On Patterns Of Dissolved Oxygen In The Skidaway River Estuary, Casey Colleen Brazell
Tidal Influences On Bacterial And Phytoplankton Abundances And The Resulting Effects On Patterns Of Dissolved Oxygen In The Skidaway River Estuary, Casey Colleen Brazell
Electronic Theses and Dissertations
Two studies were conducted to investigate the physical and biological processes contributing to the dissolved oxygen (DO) availability in the Skidaway River Estuary (SRE), Savannah, GA during the summer of 2005. A temporal study looked at changes in DO concentrations, Chlorophyll a concentrations, bacterial abundance, water depth, and salinity, every hour, for 26 hours, over both a neap and a spring tide. A spatial study looked at changes in the above variables at 5 sites along the SRE while following the tide inland during a neap high and low tide, and a spring high and low tide. DO concentrations varied …
Effects Of Habitat Quality On Reproduction In Two Georgia Populations Of Gopherus Polyphemus, Jaqueline W. Entz
Effects Of Habitat Quality On Reproduction In Two Georgia Populations Of Gopherus Polyphemus, Jaqueline W. Entz
Electronic Theses and Dissertations
Author's Abstract: The purpose of this study was to examine differences in maternal investment by examining variation in the habitat structure and reproductive parameters for two populations of Gopherus polyphemus in Southeast GA. Both habitat structure and reproductive parameters for these populations are known from a previous study, thus this study expands upon the previous one and addresses four main questions. (1) Has habitat quality changed in the past ten years within and between population sites? (2) Could a change of habitat have affected female morphology or female reproductive parameters within or between populations? (3) Is female body size shaping …