Life Sciences Commons^™

Phosphorus Recycling By Profunda Quagga Mussels In Lake Michigan, Caroline Mosley

Theses and Dissertations

Quagga mussels (Dreissena rostiformis bugensis) act as ecosystem engineers in the southern basin of Lake Michigan, altering physical habitats and biogeochemical processes. Adapted to cold and oligotrophic conditions, profunda quagga mussels thrive on the soft substrate of deeper depths. At a 55 m site (10,000 mussels m-2) offshore from Milwaukee, WI, profunda mussel biomass (g m-2) was 1/3 of biomass (g m-2) measured at a 10 m comparison site (5,000 mussels m-2). Higher densities but less biomass is due to profunda mussels having less tissue for a given length and the population per m2 comprising of mostly small mussels ( …

A Study Of The American Black Bear (Ursus Americanus) In Utah: An Analysis Of The Post-Denning Activities And Bear-Human Conflict, Julie Ann Miller

Theses and Dissertations

This study examined two different aspects of black bear (Ursus americanus) ecology in Utah. First, we determined the post-denning behaviors of female black bears in order to help management agencies protect bears from human disturbances as well as set spring hunts that minimize the taking of females with dependent young. We looked at the timing of den emergence (X = 25 March), the number of days at the den site post emergence (X = 11 days), and departure (X = 8 April) for female black bears in Utah from 2011—2013. We also analyzed the effects of cohort (lone …

Cheatgrass Die-Off Phenomena: What Are The Short And Long Term Recovery Factors Of Bromus Tectorum Stand Failure?, Joshua Alan Nicholson

Theses and Dissertations

Observations of Bromus tectorum L. (cheatgrass or downy brome) monocultures have shown that populations are susceptible to stand die-off or replacement failures. Die-offs, where the seed bank from the previous year fails to emerge, occurs in cheatgrass stands and it is unclear the trigger or cause. The fungus Fusarium has been identified in plant and seed samples from die-offs and may drive die-off activity through pathogenicity. Die-off recovery may take several years but cheatgrass populations eventually reestablish. The purpose of our study was to determine whether Fusarium is a potential player in a die-off, and understand how die-offs recover after …

Fuel Response To Mechanical Mastication Of Pinyon-Juniper Woodlands In Utah, Alan Wyatt Shakespear

Theses and Dissertations

Pinyon-juniper woodland encroachment threatens ecosystem function and diversity on sagebrush steppe. Decreased fire frequency likely favors proliferation of pinyon-juniper woodlands and subsequent decline in desirable understory species. Increased tree cover produces hazardous canopy fuel loads that contribute to severe crown fires and threaten life and property at the wildland-urban-interface. Mechanical mastication converts large canopy fuels into small woody debris, altering wildfire dynamics from a potential crown fire to a more controllable surface fire. We measured fuel loading and cover on untreated, masticated, and masticated + burned treatments on 30-m transects within 30 X 33-m subplots, representing 45 different sites throughout …

Identification Of The Infection Route Of A Fusarium Seed Pathogen Into Non-Dormant Bromus Tectorum Seeds, Janalynn Franke

Theses and Dissertations

The genus Fusarium has a wide host range and causes many different forms of plant disease. These include seed rot and seedling blight diseases of cultivated plants. The Fusarium-caused diseases of wild plants are less well-known. In this study we examined Fusarium sp. n-caused disease development on non-dormant seeds of the important rangeland weed Bromus tectorum as part of broader studies of the phenomenon of stand failure or ‘die-off’ in this annual grass. We previously isolated an undescribed species in the Fusarium tricinctum species complex from die-off soils and showed that it is pathogenic on seeds. It can cause high …

Fire And Ungulate Herbivory Differentially Affect The Sexual Reproduction Of Generalist And Specialist Pollinated Plants, Andrew Hollis Lybbert

Theses and Dissertations

Currently the size and frequency of wildfires are increasing at a global scale, including arid ecosystems that exhibit great sensitivity to disturbance. Fire effects on plant pollination and reproductive success in deserts are largely unknown. Plant dependence on animal pollinators for reproduction can increase the risk of reproductive failure if pollination services are hindered or lost. Species that depend on few taxonomically related pollinator species are expected to be most negatively affected by disturbances that disrupt pollination interactions. To assess fire and isolation effects on reproductive success in desert plant communities, and how wildfire influences the pollination success of generalist …

The Impacts Of Feral Horses On The Use Of Water By Pronghorn On The Sheldon National Wildlife Refuge, Nevada, Amy Marie Gooch

Theses and Dissertations

Feral horses occupy 31.6 million acres throughout western North America. Feral horses share similar habitats with a wide range of animal species, including pronghorn. Since horses are larger and often more aggressive than other animals of this region, they are generally socially dominant over all other native ungulate species. Pronghorn share water sources with horses in areas where both occur. In situations where horses exclude pronghorn from water, pronghorn fitness may be impaired, especially during the hottest months of the year when water is limited. The purpose of this study was to investigate interference competition between pronghorn and feral horses …

Targeted Sequencing Of Plant Genomes , Mark D. Huynh

Theses and Dissertations

Next-generation sequencing (NGS) has revolutionized the field of genetics by providing a means for fast and relatively affordable sequencing. With the advancement of NGS, whole- genome sequencing (WGS) has become more commonplace. However, sequencing an entire genome is still not cost effective or even beneficial in all cases. In studies that do not require a whole-genome survey, WGS yields lower sequencing depth and sequencing of uninformative loci. Targeted sequencing utilizes the speed and low cost of NGS while providing deeper coverage for desired loci. This thesis applies targeted sequencing to the genomes of two different, non-model plants, Artemisia tridentate (sagebrush) …

Habitat Preferences Of The Common Nighthawk (Chordeiles Minor) In Cities And Villages In Southeastern Wisconsin, Jana M. Viel

Theses and Dissertations

Limited survey data and numerous anecdotal accounts indicate that the Common Nighthawk (Chordeiles minor) is experiencing population declines in Wisconsin. However, the magnitude of the decline is unclear because current avian monitoring efforts are not conducted at dusk when Common Nighthawks are most active nor do they specifically target urban areas such as cities and villages where Common Nighthawks are known to nest on flat graveled rooftops. New urban, crepuscular monitoring methods are needed in order to gain a better understanding of current Common Nighthawk demographics in Wisconsin.

The goal of this thesis was to conduct a baseline study using …

Secondary Dormancy And Summer Conditions Influence Outcomes In The Pyrenophora Semeniperda - Bromus Tectorum Pathosystem, Katie Karen Hawkins

Theses and Dissertations

Variable mortality of Pyrenophora semeniperda–infected Bromus tectorum seeds has been referred to as a “race for survival.” Dormant seeds are highly susceptible to P. semeniperda infection. While much is known about primary dormancy little is known about secondary dormancy in B. tectorum seeds. Dormancy status is not the only variable determining outcomes within the Bromus - Pyrenophora pathosystem. Varying temperature and intermittent hydration may strongly influence germination outcomes of B. tectorum in the presence of P. semeniperda. While it has long been assumed that B. tectorum seeds are infected by P. semeniperda in the fall it was recently suggested that …

Population Genetics Of Greater Sage-Grouse In Strawberry Valley, Utah, Paula S. Dunken

Theses and Dissertations

This study examined population genetics of greater sage-grouse (Centrocercus urophasianus) in Strawberry Valley, Utah located in the north-central part of the state. The Strawberry Valley population of sage-grouse experienced a severe population decline with estimates of abundance in 1998 less than 5% (~150 individuals) of similar estimates from the 1930s (>3,000 individuals). Given the population decline and reduced genetic diversity, recovery team partners translocated sage-grouse from four different populations into Strawberry Valley over 6 years (2003-2008). Translocations have been used as a strategy to increase both population size and genetic diversity in wildlife populations. We assessed whether genetic diversity …

Plankton Trophic Structure Within Lake Michigan As Revealed By Stable Carbon And Nitrogen Isotopes, Zachery G. Driscoll

Theses and Dissertations

Zooplankton represent a critical component of aquatic food webs in that they transfer energy from primary producers to higher trophic positions. However, their small size makes the application of traditional trophic ecology techniques difficult. Fortunately, novel techniques have been developed that can be used to elucidate feeding information between zooplankton species. I used the analysis of stable carbon and nitrogen isotope ratios to estimate the trophic structure of Lake Michigan's zooplankton community. The major zooplankton species, three size classes of seston, and seston from specific water column depths were collected in 2011 and 2012 for stable isotope analysis. Trophic position …

Nursery Pig Growth Response To Feed Ingredients And Feed Additives: I ). Spray-Dried Blood Plasma Vs. Spray-Dried Egg Effect On Nursery Pig Growth Performance Ii ). Effect Of Α-Galactosidase And Citric Acid On Nursery Pig Growth Performance When Added To A Corn-Soybean Meal Diet, Elizabeth Kaye Pegg

Theses and Dissertations

Nursery pigs are defined as newly weaned pigs adjusting to a solid-plant based diet after being weaned from a milk-based diet. Weaning has nutritional, environmental, social, and physiological impacts on the nursery pig. Nutrition is modified to accommodate changing needs of the nursery pig. The nursery pig diet is developed by adding highly digestible animal proteins to the standard corn-soybean meal swine diet. Development of the nursery diet improves pig performance but animal-based proteins can be expensive and do not address undigestible components of the plant-based ingredients. Addition of lower-cost animal proteins, addition of enzymes, and addition of acidifiers have …

Nitrogen Use Efficiency Of Polymer-Coated Urea, Curtis J. Ransom

Theses and Dissertations

Plants require N to complete their life cycle. Without adequate concentration of N, crops will not produce their potential yields. For turfgrass systems, N fertilizer application allows for the maintenance of functional, aesthetic, and recreational properties. However, fertilizer mismanagement is common and leads to N pollution in the environment. Controlled-release and slow-release fertilizers can enhance nitrogen (N)-use efficiency, reduce N pollution, minimize the need for repeated fertilizer applications, and reduce turfgrass shoot growth and associated costs. In order to evaluate the effectiveness of these fertilizers in the Intermountain West, research is needed. The timing of N release was evaluated for …

Wet-Thermal Time And Plant Available Water In The Seedbeds And Root Zones Across The Sagebrush Steppe Ecosystem Of The Great Basin, Nathan Lyle Cline

Theses and Dissertations

Following wildfires, plant materials are direct-seeded to limit erosion and annual weed invasion. Seedlings often fail to establish because selected plant materials are not always well adapted to local soil moisture and temperature conditions. In an effort to help improve plant materials selection and to evaluate sites potential revegetation, we have worked toward developing methodology to predict germination and root growth based on site specific soil moisture and temperature conditions. First, we characterized the seedbed environment of 24 sagebrush (Artemisia spp.) steppe sites throughout the Intermountain West to determine the wet-thermal time of five temperature ranges relevant to germination …

Soil Fertility Status And Degradation Of 2, 4, 6-Trinitrotoluene Contaminated Soils, Chelsea Kae Katseanes

Theses and Dissertations

Current models for predicting the environmental fate of munitions constituents (MC) in soils are based mostly on chemical distribution parameters and neglect the larger considerations of other soil parameters. We are working towards a new approach based on the whole soil activity for predicting the long-term residence time and fate of MC in soils with connection to agronomic soil fertility concepts. These relationships are demonstrated by correlating experiments involving full physical and chemical characterization of eight taxonomically distinct soils, with batch reactor studies determining MC degradation potential. Soils were incubated in a slurry for 10 days in a closed reactor …

Fire Severity And Size Alter Quaking Aspen (Populus Tremuloides) Regeneration And Defense Against Ungulate Herbivory, Ho Yi Wan

Theses and Dissertations

Human activities and rapid global climate change are altering fire regimes with potential threat to the stability of aspen ecosystems in North America. Aspen is an early successional species that plays an important role in post-fire forest reestablishment, but chronic browsing on juvenile aspen by large ungulate herbivores after fire can be detrimental and lead to regeneration failure. Although larger and more severe fires are expected to become more prominent, whether and how this may influence aspen and ungulate communities remains unclear. The objective of this research was to examine how the relationship between aspen and ungulate communities might be …

Parturition Of Mule Deer In Southern Utah: Management Implications And Habitat Selection, Eric D. Freeman

Theses and Dissertations

Mule deer (Odocoileus hemionus) are an ecologically, economically, and socially important species across much of the western United States. As such, populations and habitat are intensely managed by state game agencies. However, populations have been declining in recent decades and several factors have been implicated (e.g., climate, predation, competition, and habitat availability). Population dynamics of mule deer are driven by a combination of survival of adults and juveniles and reproductive rates. While adult female mule deer typically have consistently high annual survival rates (85% annually), juveniles are more easily affected by stressors (biotic and abiotic conditions) and therefore …

Post-Den Emergence Behavior And Den Detection Of Polar Bears (Ursus Maritimus) In Northern Alaska And The Southern Beaufort Sea, Rusty Wade Robinson

Theses and Dissertations

Pregnant polar bears (Ursus maritimus) construct maternal dens out of snow in the autumn where they give birth to and raise altricial young. In recent years, there has been a decrease in polar sea ice extent and thickness, which has led to changes in denning behavior. One such change in the southern Beaufort Sea (SBS) is that polar bears are selecting maternal den sites on land, rather than on unstable sea ice. This change, coupled with expanding petroleum exploration along Alaska's North Slope, heightens the likelihood of bear-human interactions at maternal den sites. The purpose of this research …

"Mining" For A Reference Condition In Southern West Virginia Streams, Matthew Rouch

Theses and Dissertations

Quarterly samples were used to estimate assemblage-level (all species combined) fish production within three minimally-impacted, southern West Virginia streams. The total annual fish production estimate was highest in Slaunch Fork (37.52 kg∙ha^-1∙y^-1), a tributary of the Tug Fork River, and lowest in Cabin Creek (10.59 kg∙ha^-1∙y^-1), a Guyandotte River tributary. Creek Chub Semotilus atromaculatus, Mottled Sculpin Cottus bairdii and Blacknose Dace Rhinicthys atratulus were the most abundant species among sites, accounting for >90% of all sampled individuals. Reference condition criteria were also selected and metrics calculated for each of the three …