Ecology and Evolutionary Biology Commons^™

Remote Estimation Of Regional Lake Clarity With Landsat Tm And Modis Satellite Imagery, Ian M. Mccullough

Electronic Theses and Dissertations

Water clarity is an ideal metric of regional water quality because clarity can be accurately and efficiently estimated remotely on a landscape scale. Remote sensing of water quality is useful in regions containing numerous lakes that are prohibitively expensive to monitor regularly using traditional field methods. Field-assessed lakes generally are easily accessible and may represent a spatially irregular, non-random sample. Remote sensing provides a more complete spatial perspective of regional water quality than existing, interest-based sampling; however, field sampling accomplished under existing monitoring programs can be used to calibrate accurate remote water clarity estimation models. We developed a remote monitoring …

Increase In Ponderosa Pine Density In The Nebraska Sandhills: Impacts On Grassland Plant Diversity And Productivity, Alexa Armstrong

Department of Environmental Studies: Undergraduate Student Theses

Increase in woody species encroachment into semi-arid grasslands and savannas has been of great concern at a global level. Temperature and precipitation are key factors determining vegetation cover; however other factors, such as fire regime and grazing may be at play in semi-arid ecosystems. Historically, in Nebraska’s semi-arid grasslands, woody species have been controlled by periodic fires. Changes in social values and land use, fire suppression, overgrazing, increased N deposition, and climate change, have attributed to the observed shift from grasslands to shrublands or woodlands. The primary objectives of this study were to determine the impacts of Ponderosa pine ( …

The Herring River Estuary: Understanding Salt Marsh Restoration And How To Predict The Response Of Phragmites Australis To Increased Tidal Flow, Theresa Murphy

Senior Honors Projects

My presentation invites you to learn about what is involved in planning a salt marsh restoration project. The Herring River Estuary is a disturbed salt marsh ecosystem at Cape Cod National Seashore which has been diked since 1909. The National Park Service (NPS), in cooperation with many partners, is engaged in efforts to restore the now impacted 1,100 acre estuary by re-introducing tidal flow. There is significant complexity involved in trying to restore such an intricate system- from the multitude of environmental factors to important social and economic consequences. There are also several benefits to restored tidal flow. My thesis …

The Effects Of White Noise Disturbance On Zebra Finch Behavior; Does Disturbance Predictability Matter?, Kathryn Chenard

Honors College

It is undeniable that the progress of human civilization has altered the natural landscape of the world in ways that range from the merely aesthetic to the irreparably destructive. Some impacts are patently obvious. Others may not be as obvious to the casual observer, and yet they can be just as important in terms of truly understanding not only our impact on the world around us, but how we can mitigate this impact.

One of the most far-reaching of these latter impacts is the increased and altered levels of background noise upon the natural acoustic landscape. These changes have the …

Territories,Territoriality, And Conservation Of The Louisiana Waterthrush And Its Habitat, The Watershed Of The Upper Buffalo National River, Leesia Cheryl Marshall

Graduate Theses and Dissertations

The Louisiana Waterthrush, Parkesia motacilla, is a migratory wood-warbler and breeding season resident of the eastern United States. Males defend breeding territories that extend linearly along clear, fast-flowing, gravel-bottomed, forest streams. Defense includes two song types, primary and extended song. As riverine specialists, birds rely upon aquatic invertebrates as prey and riparian habitat features for nesting. They use a unique foraging maneuver, leaf-pulling, that involves picking up or pulling a leaf from water, and turning it over to search for prey. Their relationship with riparian habitat introduces potential for Louisiana Waterthrushes to serve as indicators of stream health. The …

Genetic Variation In Potentially Virulent Vibrio Parahaemolyticus From The Northern Gulf Of Mexico, Nicholas Felix Noriea Iii

Dissertations

Vibrio parahaemolyticus (V_p) is a gram-negative bacterium found naturally in marine and estuarine environments. V_p is found in oysters including those which are later consumed by the public. Sub-populations of potentially virulent Vp contain specific virulence factors and are relevant human pathogens capable of causing gastroenteritis, wound infection, and death. The tdh and trh genes, both encoding hemolysins, have been correlated with the majority of clinical V_p isolates but have not been shown to be the definitive virulence factors.

A total of 146 V_p isolates from the northern Gulf of Mexico were collected and probed …

Effects Of Hypoxia And 4-Tert-Octylphenol On Gene Expression Profiles Of The Sheepshead Minnow (Cyprinodon Variegatus), Arthur Alan Karels

Dissertations

Hypoxia occurs in estuaries of northern Gulf of Mexico and world-wide, with increasing frequency/severity via eutrophication and anthropogenic influences. Hypoxia inducible factors (HIFs) form transcriptional complex and bind DNA at hypoxia responsive elements (HREs) in promoter regions of genes needed for systemic and cellular adaptation of fish to low dissolved oxygen (hypoxia, DO <2.0 mg/ml). Hypoxia-induced activation of HIF-αs can lead to a cascade of downstream activation, such as erythropoietin (EPO). Return to normal DO levels (normoxia), prolyl hydroxylases (PHDs) are activated to degrade HIF-αs back to baseline. Fish are affected by environmental estrogen mimics, like 4-tert-octylphenol (4tOP), binding estrogen receptor alpha (ERα) at estrogen responsive elements (EREs) and activating genes vitellogenin (VTG). Previous research showed overlap or crosstalk between these two mechanistic pathways. Hypoxia triggers unknown factors regulating ERE-mediated ERα signaling pathway, and stressor combinations could increase/decrease hypoxic or endocrine pathway. Research examined molecular/physiological effects of hypoxia (acute and chronic, moderate and severe) and 4tOP (~60μg/L)on adult male and/or female sheepshead minnow (Cyprinodon variegatus). Three genes identified, cloned, and sequenced (HIF-1α, HIF-2α, and PHD3), plus previously identified genes EPO and VTG, were examined in liver/testes exposed to hypoxia and/or 4tOP for cellular/physiological changes. Endpoints examined included mRNA expression from real-time PCR of HIF-1α, HIF-2α, PHD3, EPO, and VTG using cDNA from total RNA extracts, and microarray analyses of genes expressed during the transition from hypoxia back to normoxia. Phylogenetic analyses confirmed isolation of two HIF-α isofoms (HIF-1α and HIF-2α) and the PHD3 isoform. Significant up-regulation of PHD3 occurred within 10 hrs of chronic hypoxia, and persisted when severe (1.5 mg/L) and declined when moderate (~2.5mg/L). Significant up-regulation of HIF-1α and EPO occurred within 30 minutes to 2 hours of onset of acute severe and very severe (~1.08mg/L) hypoxia. Hypoxia acted similar to an estrogen mimic, with huge up-regulation of VTG gene expression in males, and increased VTG levels (additive effect) when hypoxia was combined with 4tOP. Microarray analyses showed 125 genes with significant transcriptional change, with up- or down-regulation from transitions of: (1) hypoxia (72 hrs) to normoxia (74 hrs) and (2) hypoxia+4tOP (72 hrs) to normoxia+4tOP (74 hrs).

The Effects Of Nutrient Limitation And Cyanophage On Heterotrophic Microbial Diversity, Claire Elyse Campbell

Masters Theses

Marine viruses are critically important in the regulation of biogeochemical cycles and host microbial communities. In this study, we tested whether the indirect effects of virus predation on a phototroph (i.e., Synechococcus) affected the composition of co-occurring heterotrophic bacteria under nitrogen and phosphorus limitation in long-term chemostat experiments. Using 454 Titanium barcoded pyrosequencing of the 16S rRNA gene, microbial diversity and technical (i.e., sequencing) reproducibility were assessed for nine individual chemostats across five different time points. A total of 325,142 reads were obtained; 194,778 high-quality, non-cyanobacterial sequences were assigned to 110 OTUs. Our results show high reproducibility …

Identifying The Spatial Distribution Of Three Plethodontid Salamanders In Great Smoky Mountains National Park Using Two Habitat Modeling Methods, Matthew Stephen Kookogey

Masters Theses

The main objective was to create habitat models of three plethodontid salamander species (Desmognathus conanti, D. ocoee, and Plethodon jordani) in GSMNP. To investigate the relationships between salamanders and their habitats, I used three models—logistic regression with use-availability sampling, logistic regression with case-control sampling, and Mahalanobis distance (D²)—for each species to gain a robust view of the relationships. The secondary objective was to compare the different modeling methods within and across the three species. Elevation was the dominant variable for all three species.

D² for D. conanti predicted low elevations, close proximity …

American Pika (Ochotona Princeps): Persistence And Activity Patterns In A Changing Climate, Cody P. Massing

Master's Theses

An increasing amount of evidence suggests that as temperatures increase, montane animals are moving upward in elevation (IPCC 2007, Parmesan and Yohe 2003). As suitable habitats rise in elevation and then disappear altogether, these animals could be pushed to extinction. The American pika, Ochotona princeps, is a montane mammal that lives in western North America, usually at elevations above 1500 m (Smith and Weston 1990). Recent evidence suggests that pika population numbers are dropping in response to rising temperatures (Beever et al. 2010). The pika is a small herbivorous lagomorph, a relative of hares and rabbits. Its habitat is …

Prehistoric Foraging Strategies In The Piute Valley Of Southern Nevada, Christopher Alan Brosman

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Piute Valley of Southern Nevada is an incredibly diverse but arid zone in the eastern portion of the Mojave Desert. Most of this diversity can be attributed to the elevation shifts ranging from the Colorado River basin to the peaks of the surrounding mountain ranges. These peaks and valleys provide a multitude of resource zones in which prehistoric hunter-gatherers could provision themselves throughout the year. For this thesis I have used archaeological survey, paleo-climate models, life-sciences data and ethnographic research to perform an in-depth land use analysis of prehistoric forager adaptations to this challenging but life-sustaining environment.

Recent investigations …

Exploring The Seed Bank Dynamics Of Red Brome: Longevity, Density, And Relationship To Fire, Benjamin S. Jurand

UNLV Theses, Dissertations, Professional Papers, and Capstones

This research explores several untested aspects of the seed bank characteristics of red brome (Bromus rubens), an invasive annual grass in southwestern United States arid lands. Red brome is a formidable competitor to native plant species, both annual and perennial alike, and produces many seeds that germinate easily. The stalks of red brome contribute continuous-cover fuel loads that facilitate wildfires destructive to mature native Mojave Desert plant communities. This makes it a priority species for land managers, particularly when dealing with recovery after fire.

This project addressed questions related to the longevity of red brome seeds in soil seed banks …

Investigating Three Decades Of Vegetation Change In A Mojave Desert Mountain Range, Chris Lee Roberts

UNLV Theses, Dissertations, Professional Papers, and Capstones

This project is a vegetation change study spanning 29 years in the Newberry Mountains of Southern Nevada. Long term monitoring data are crucial for understanding the effects of climate change on vegetation dynamics. Successful management intervention in vegetation change will require identification of early indicator plant species and their responses to climatic cues. This project is one of the oldest comparisons of resurveyed Mojave vegetation community plots with repeatable methodology and the longest survey interval reported for the southeastern Mojave Desert. 103 plots were relocated and resurveyed based on data methods in Jim Holland's thesis titled "A Vegetative Analysis of …

Natural And Constructed Wetlands For Ecosystem And Engineering Services In The Arid And Semi-Arid Regions, Achyut Raj Adhikari

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Las Vegas Wash (LVW) has undergone significant wetlands degradation and soil erosion over the past thirty years due to increasing flow resulting from urbanization and large rainfall events in the Las Vegas Valley Watershed. The increased flow and associated pollution load in the LVW and its adverse impact in Lake Mead have alerted stakeholders to pay a greater attention to explore alternative measures for rehabilitation of wetland ecosystems. This dissertation, using the case of changes in LVW, analyzes and describes ecological and engineering services provided by wetlands in arid and semi-arid regions and provides a knowledge base that can …

A Comparative Analysis Of The Relative Water Content Of The Pollen Of Early Diverging Angiosperms, Andrew Robert Moffatt

Chancellor’s Honors Program Projects

No abstract provided.

Hemiparasitic Castilleja Promotes Plant Diversity In An Alpine Meadow Ecosystem, Johannah Reed

Chancellor’s Honors Program Projects

No abstract provided.

Comparing Volunteer And Professionally Collected Monitoring Data From The Rocky Subtidal Reefs Of Southern California, Usa, David Gillett, Daniel Pondella, Jan Freiwald, Kenneth Schiff, Jennifer Caselle, Craig Shuman, Stephen Weisberg

Daniel Pondella

Volunteer-based citizen monitoring has increasingly become part of the natural resources monitoring framework, but it is often unclear whether the data quality from these programs is sufficient for integration with traditional efforts conducted by professional scientists. At present, the biological and physical characteristics of California’s rocky reef kelp forests are concurrently monitored by two such groups, using similar methodologies—underwater visual census (UVC) of fish, benthic invertebrates, and reef habitat, though the volunteer group limits their sampling to transects close to the reef surface and they use a more constrained list of species for enumeration and measurement. Here, we compared the …

How Does Gene Flow Limit Local Adaptation At A Species Range-Edge? An Artificial Selection Drosophila Model, Justin P. Saindon

Electronic Thesis and Dissertation Repository

Gene flow has the potential to create species range limits by impeding adaptation to selective pressures at the range-edge, but it is unclear whether there is a threshold level of gene flow that causes this effect. This gene swamping hypothesis was tested using laboratory populations of Drosophila melanogasterunder selection for desiccation resistance, and subject to a gradient of migration from unselected populations. Desiccation tolerance was impeded across the entire migration gradient, and populations receiving intermediate levels of migration exhibited no tolerance for desiccation stress, following twelve selection events. Female, but not male, flies increased desiccation tolerance following selection by …

Spatio-Temporal Differentiation And Sociality In Spiders, Jessica Purcell, João Vasconcellos-Neto, Jeffrey Alan Fletcher, Marcelo O. Gonzaga, Leticia Avilés

Systems Science Faculty Publications and Presentations

Species that differ in their social system, and thus in traits such as group size and dispersal timing, may differ in their use of resources along spatial, temporal, or dietary dimensions. The role of sociality in creating differences in habitat use is best explored by studying closely related species or socially polymorphic species that differ in their social system, but share a common environment. Here we investigate whether five sympatric Anelosimus spider species that range from nearly solitary to highly social differ in their use of space and in their phenology as a function of their social system. By studying …

The Effects Of Invasive Grasses On The Survival And Germination Of Native Forbs, Rachel A. King

Scripps Senior Theses

Invasive species are an increasingly severe conservation problem that can dramatically alter native plant communities. Although ecologists have proposed many mechanisms for the dominance of invasive species, superior competitive ability is one of the longest standing hypotheses. In winter annual plant communities, germination timing affects competition among plants. I hypothesized that grass invasion has changed the costs and benefits of early and late germination, and that species with flexible germination timing would compete better with invasives. Experiments at the Bernard Field Station in Claremont, CA and germinator trials in a controlled environment were used to examine the survivorship and germination …