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Ecology, Phylogenetics, And Conservation Of Draba Asterophora Complex: A Rare, Alpine, Endemic From Lake Tahoe, Usa, Emily Ruth Smith Putnam

Theses and Dissertations

Rare, alpine, endemic species are particularly at risk for extinction. Alpine environments are especially vulnerable to climate change and human impacts, such as ski resort development and snowmaking. Draba asterophora Payson is a rare, alpine species that occurs only in three disjunct mountain-top regions surrounding Lake Tahoe. It is currently threatened by human impacts, such as ski resorts, as well as indirect influences of climate change and therefore in need of better understanding for conservation purposes. Draba asterophora may be able to serve as a case study for other similarly vulnerable, rare, alpine, endemic species with conservation needs. We utilized …

Environmental Regulation Of Tidal Wetland Microbial Communities And Associated Biogeochemistry, Ember Morrissey

Theses and Dissertations

Microbial communities play an essential role in carrying out the biogeochemical cycles that sustain life on Earth, yet we know very little about their ecology. One question of particular interest is how environmental conditions shape microbial community structure (i.e., the types of organisms found in the community and their relative abundance), and whether such changes in structure are related to biogeochemical function. It is the aim of this dissertation to address this question via the examination of carbon (C) and nitrogen (N) cycling in wetland ecosystems, which due to their diverse hydrology have a profound influence on biogeochemical cycles. With …

Distribution And Abundance Of Anopheles Spp. In The Lower Rio Grande Valley, South Texas, Norma Hermelinda Martinez

Theses and Dissertations - UTB/UTPA

This study investigated the relationship between Anopheles abundance, collection sites and environmental variables in the Lower Rio Grande Valley, South Texas. In addition, species composition in the Lower Rio Grande Valley was determined in 2011. A total of 6772 female mosquitoes were identified to six genera and 27 species. The most prevalent genera collected were Culex (53.9%), Ochlerotatus (25.6%) and Aedes (13.6%). Anopheles mosquitoes were collected using resting boxes during summer 2012 at multiple locations along the Lower Rio Grande Valley. ArcGIS was used to identify land cover characteristics and nearest water sources at mosquito collection sites. Estero Llano Grande …

Winter Waterbird Ecology On The Great Salt Lake, Utah, And Interactions With Commercial Harvest Of Brine Shrimp Cysts, Anthony J. Roberts

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Interactions among commercial fisheries and birds have been studied in open ocean ecosystems and at aquaculture facilities. On the Great Salt Lake (GSL), Utah, USA, a commercial harvest of brine shrimp (Artemia franciscana) eggs (i.e. cysts) occurs annually during fall and winter. Coinciding with commercial harvest is the use of the GSL by millions of waterbirds which has the potential to result in conflict among industry and birds. The objectives of my research were to examine fall and winter ecology of birds using the GSL and interactions with the brine shrimp cyst harvest. I examined the influence of temperature and …

Effect Of Prescribed Burning In The Forests Of Buffalo National River, Arkansas, Francis Ndar Onduso

Graduate Theses and Dissertations

Prescribed burning (also referred to as controlled or hazard reduction burning) refers to the use of fire under controlled conditions to achieve a desired end product or goal. However, the nature and magnitude of the changes that result from prescribed burning are still incompletely known, and this is especially true for the forests of the Ozarks of northern Arkansas. The overall objective of the research project described herein was to obtain the data necessary to develop a better understanding of these changes, particularly as they relate to the use of prescribed burning as a management technique in the Buffalo National …

Environmental Constraints On Cyanomyophage Abundance In The Subtropical Pacific Ocean, Tiana Maria Pimentel

Masters Theses

Viruses are abundant in the world’s oceans and are thought to be important participants in marine biogeochemical cycling. Of these viruses, cyanophages are considered especially important because they infect and lyse cyanobacteria, which are some of the main primary producers in marine environments. Cyanophages are thought to influence the abundance and diversity of cyanobacterial populations and impart significant mortality, thereby affecting primary productivity and microbial community structure. Despite their ecological relevance, little is known about how environmental factors shape cyanophage abundance and diversity over large temporal and spatial scales. To address this gap in knowledge, seawater samples were collected during …

Genetic And Ecological Characterization Of Indigoidine Production By Phaeobacter Sp. Strain Y4i, William Nathan Cude

Doctoral Dissertations

The Roseobacter clade is a widely distributed, abundant, and biogeochemically active lineage of marine alpha-proteobacteria. Members of the Roseobacter lineage are prolific surface colonizers in marine coastal environments, and antimicrobial secondary metabolite production has been hypothesized to provide a competitive advantage in colonization. In this work, Phaeobacter sp. strain Y4I was found to produce the water soluble, blue pigment indigoidine via a nonribosomal peptide synthase-based biosynthetic pathway encoded by a novel series of genetically linked genes, termed igiBCDFE. Comparison of wildtype, non-pigmented, and hyper-pigmented Y4I insertional mutants demonstrated a perfect correlation between indigoidine production and the inhibition of Vibrio …

The Effects Of Calcium Concentration And Food Levels On Daphnia, Fawn Goodberry

Biology Theses

Many physiological processes of Daphnia are negatively affected at low calcium concentrations. The concentration of calcium within lake water influences how Daphnia populations will survive and reproduce in natural environments. An experiment was designed to test the effects of calcium concentration and food level on the growth and reproduction of a Daphnia hybrid. Daphnia pulex x Daphnia pulicaria were reared in a soft water medium at three calcium concentrations (2.5mg/L, 1.0mg/L, 0.50mg/L) and high and low food levels (5.6 x 10⁵ and 5.6 x 10⁴ cells of the algae Ankistrodesmus sp.) in a 2 x 3 factorial …

Integrating, Developing, And Testing Methods To Generate More Cohesive Approaches To Biogeographic Inference, Mallory Elizabeth Eckstut

UNLV Theses, Dissertations, Professional Papers, and Capstones

As a fundamental component of the developing discipline of conservation biogeography, broadscale analyses of biotic assembly and disassembly across multiple temporal and spatial scales provide an enhanced understanding of how geologic transformations and climate oscillations have shaped extant patterns of biodiversity. As with any scientific field, there are limitations in the case of biogeographic historical reconstructions. Historical reconstructions are only as robust as the theoretical underpinnings of the methods of reconstruction (including data collection, quality, analysis, and interpretation). Nevertheless, historical reconstructions of species distributions can help inform our understanding of how species respond to environmental change.

My dissertation takes a …

Greater Sage-Grouse Habitat Selection And Use Patterns In Response To Vegetation Management Practices In Northwestern Utah, Stephanie E. Graham

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Greater sage-grouse (Centrocercus urophasianus; sage-grouse) are a sagebrush obligate species and an indicator of sagebrush (Artemisia spp.) habitat quality. Sage-grouse populations have declined across western North America. Fragmentation of landscapes and habitat loss have been identified as factors that negatively impact sage-grouse populations. Wildfires can increase the distribution of invasive plants and contribute to fragmentation and habitat loss across sagebrush ecosystems. Greenstripping has been identified as a technique to reduce the threat of wildfire and subsequent spread of invasive species. Forage kochia (Bassia prostrata) is a semi-shrub that contains a high moisture content year-round, high …

Ecology Of Coyotes On The Valles Caldera National Preserve, New Mexico: Implications For Elk Calf Recruitment, Suzanne J. Gifford

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Valles Caldera National Preserve (VCNP) managers were concerned about low elk recruitment observed at the same time as an apparent increase in sightings of coyotes and observations of coyote predation on elk calves. The goal of this study was to describe coyotes’ ecological interactions with elk, particularly coyote diet and movements on the Valle Grande, a large grassland meadow in the southeastern portion of the VCNP.

We examined coyote diet by quantifying undigested remains of food items in coyote scats (feces). The most frequent taxa were rodents (montane voles and pocket gophers), elk (adult and calf), insects (grasshoppers and beetles), …

Roads And The Reproductive Ecology Of Hesperidanthus Suffrutescens, An Endangered Shrub, Matthew B. Lewis

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

We studied the pollination ecology of the endangered Utah desert shrub, shrubby reed-mustard (Hesperidanthus suffrutescens). We also studied the impacts that dust from unpaved roads has on successful reproduction. In addition, we looked at the relationship between the total number of plants, the spacing of plants, and reproduction. We found that shrubby reed-mustard requires pollinators for successful pollination. Pollinators include many small native bees from the genera Andrena, Dialictus, and Halictus. Additionally, we found that reproduction of shrubby reed-mustard is limited, possibly due to scarcity of these bees. We found that dust from the road …

The Effect Of Ph On The Metal Binding Capabilities Of Exopolymeric Substances From A Marine Benthic Diatom, Vanessa O'Donnell

All Theses And Dissertations

The marine sediment-water interface is a dynamic microenvironment containing diatoms, which produce exopolymeric substance (EPS). EPS has various functions for individual cells and for marine ecosystems. EPS substance is a species-specific composition that has strong absorptive qualities and is able to bind metals from even a very dilute aqueous solution. As industrially derived metals tend to accumulate in marine mudflats, where diatoms are the major EPS producing organisms, it is important to determine how marine benthic diatom EPS will bind with metals. To address the metal binding properties of diatom EPS, Cylindrotheca closteriums’ EPS was isolated by tangential flow filtration, …

Activity Patterns And Spatial Resource Selection Of The Eastern Garter Snake (Thamnophis Sirtalis Sirtalis), Matthew Gregory Most

Master's Theses

Snake species usually exhibit seasonal variations in activity patterns, home-range size and the use of respective habitat. Using mark-recapture protocols I marked 96 individual Thamnophis sirtalis sirtalis specimens in Lake Forest, IL to determine the independent variables that best explained habitat selection in a population of Eastern Garter Snakes (T. s. sirtalis). Specifically, I focused on the relationship between seasonal movement and home range size of male and female garter snakes. I analyzed the habitat preferences and spatial ecology of Eastern Garter Snakes during the 2011 sampling season and modeled the relationship between preferred or avoided habitat, in conjunction with …

Biology And Ecology Of Glyphosate-Resistant Giant Ragweed, Kabelo Segobye

Open Access Theses

Giant ragweed (Ambrosia trifida L.) is a competitive annual plant found in disturbed landscapes and is the most troublesome weed in Indiana and the US Corn Belt. It is one of the most common and problematic weeds in corn and soybean production. The introduction of herbicide glyphosate, N-(phosphonomethyl) glycine in early 1970's provided farmers with a better and low-cost tool to control weeds. The use of glyphosate drastically increased after the development of glyphosate resistant agronomic crops in 1996 and was use as a post-emergence selective herbicide. This led to overreliance and repeated use of glyphosate for weed control especially …

Evaluating The Utility Of Beaver Reintroduction Programs For Enhancing Habitat For Rainbow Trout And Steelhead, Jonathan Rodger Hegna

All Master's Theses

Beaver reintroduction programs are increasingly being viewed as a way to enhance salmonid habitat and production. However, the actual effectiveness of using beavers as a habitat enhancement tool for ESA listed steelhead Oncorhynchus mykiss populations is unknown. We examined the type of habitat, at both the microhabitat and mesohabitat levels, preferred by steelhead in three small streams in the upper Yakima Basin, WA through standard snorkel surveys and habitat measurements. Our results suggest that steelhead in small streams strongly prefer (relative to availability) microhabitats that have deeper water(> 30 cm), slow stream velocities(< 0 .05 mis), and complex cover types. Habitat partitioning among the size-classes (small< 50 mm, medium 50-90 mm, large> 90 mm total length, TL) principally operated …

Ecology Of Glacial Relict Fishes In South Dakota's Sandhills Region, Eli Felts

Electronic Theses and Dissertations

Native stream fish zoogeography has changed substantially across North America during the last century as habitat degradation, stream fragmentation and introductions of nonnative species have led to numerous extinctions, extirpations and altered distributions. Insufficient information regarding imperiled species often results in reactive, rather than proactive, management, and knowledge of species status and ecology is critical in identifying conservation priorities. South Dakota populations of three dace species (northern redbelly dace Chrosomus eos, finescale dace Chrosomus neogaeus, and pearl dace Margariscus margarita) are relict of Pleistocene Glaciation and are isolated from the northern core of their distribution, but little information exists regarding …

Modeling Approaches, Physiological Responses, And Climate Change: How Good Is "Good Enough?", Nicole Kish

Theses and Dissertations

Predicting spatial and temporal patterns in the responses of organisms and ecosystems to climate change has emerged as a major focus of macrophysiological research, with much work centered on the impacts of temperature. A potential difficulty lies in the observation that measures of 'habitat' such as air, land and sea surface temperature often differ greatly from the body temperature actually experienced by organisms, as the latter drives reproduction and survival. As a result, it is unclear how often these simple measurements of habitat are 'good enough' for predicting physiological stress in the field, and when more complicated methods are needed. …

Family Matters: An Analysis Of Genetic Relatedness Of Tetraclita Rubescens (The Pink Volcano Barnacle) Over Several Spatial Scales At Monterey And Bodega Bay, California, Kelly N. Chang

Scripps Senior Theses

Inbreeding involves the mating of closely related individuals at a higher frequency than at random; this can decrease the average fitness of populations and individuals by reducing the presence of heterozygotes and augmenting the expression of deleterious genes. Since marine invertebrates exhibit widespread dispersal, their potential for inbreeding is often disregarded. The adult sessile state of barnacles creates the potential for inbreeding as a result of necessary copulation between neighboring individuals. Depending on the degree of mixing that occurs during dispersal, closely related individuals or siblings may settle in close proximity, generating the possibility of kin aggregation and consequent inbreeding. …

Quantifying Carbon Allocation To Mycorrhizal Fungi By Temperate Forest Tree Species Across A Nitrogen Availability Gradient, Shersingh Joseph Tumber-Davila

Honors Theses and Capstones

Terrestrial ecosystems make up the largest carbon pool with a major portion of that being forests. With carbon being a major concern due to global climate change, being able to make accurate models is increasingly important. Studies have shown that trees may allocate up to 50% of their photosynthetically fixed carbon underground; however these values haven’t been accurately quantified and underground carbon allocation has been historically overlooked. Mycorrhizal fungi may be a large portion of underground carbon allocation, as they have a symbiotic relationship with trees where they provide the plant with water and nutrients in return for sugars (carbon). …

Population Genetics And Ecology Of Regional Malaria Vectors In Amazonian Brazil, Sascha Naomi Mckeon

Legacy Theses & Dissertations (2009 - 2024)

Species complexes are common among anopheline mosquitoes, but only some members of complexes are disease vectors. Research involving overall patterns of divergence, phylogenetic relationships and population structure is partly driven by the operational need to be able to reliably distinguish component taxa that may be involved in malaria transmission. Anopheles triannulatus, An. nuneztovari and An. albitarsis are broadly distributed species complexes that contain local and regionally important malaria vectors, whose genetic diversity has been largely overshadowed by studies involving An. darlingi, the principal vector of Central and South America. I have analyzed the ecological suitability of habitats and geographical ranges …

Likely Successors Of Ash Species In Response To The Emerald Ash Borer In Ohio Forests, Brian Michael Good

Browse all Theses and Dissertations

Invasive species have the capability to alter landscapes and change the composition of a forest in a very short time. The recent invasive pest, Agrilus planipennis, emerald ash borer, was unintentionally introduced to the United States via ship route to Michigan. The pest attacks and kills all five native ash species in Ohio. This study focused on an area in west central Ohio not yet affected by the borer. Ash centered plots were used to record all species and sizes (diameter at breast height) within a 5m radius of a central ash tree. Plots ranged in topography and all five …

A Study Of The Spatial Dynamics Of Some Introduced Avian Species In The Southwest Region Of Western Australia, Desiree L. Moon

Theses: Doctorates and Masters

The Southwest region of Western Australia is a recognised ‘biodiversity hotspot’, as it possesses high levels of biodiversity and endemism; it also holds a number of species threatened by habitat loss. The arrival of Europeans in the region wrought major changes on the natural landscape. Extensive tracts of bushland were cleared for housing, infrastructure, forestry, farming, and mining. Another challenge to regional biodiversity was the spread of exotic plants and animals (including birds); the latter provide the focus for the present study. The research examines four bird species that colonised the Southwest region following European settlement: Australian White Ibis (Threskiornis …