Life Sciences Commons^™

Investigation Of The Determinants Of African Savanna Vegetation Distribution: A Case Study From The Lower Omo Basin, Ethiopia, Catherine A. Schloeder

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The Ethiopian Wildlife Conservation Organization has little information on the extent and ecological determinants of plant species composition and distribution in Omo National Park. Elsewhere, the determinants of African savanna vegetation dynamics have been the focus of numerous investigations, yet our understanding of the hierarchical nature and relative importance of any relationships remains very general. As well, our ability to derive predictions about vegetation responses is limited to extreme generalizations. African savanna landscape ecotones have received even less attention than most landscapes. In this dissertation, I test hypotheses about plant species distribution-determinant relationships in Omo National Park, a park that …

Predictively Mapping The Plant Associations Of The North Fork John Day Wilderness In Northeastern Oregon Using Classification Tree Modeling, Alison M. Kelly

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Shifting perspectives on restoration and management of public lands in the inland West have resulted in an increased need for maps of potential natural vegetation which cover large areas at sufficient scale to delineate individual stands. In this study, classification tree modeling was used to predictively model and map the plant association types of a relatively undisturbed wilderness area in the Blue Mountains of northeastern Oregon. Models were developed using field data and data derived from a geographic information system database. Elevation, slope, aspect, annual precipitation, solar radiation, soil type, and topographic position were important predictor variables. The model predicted …

Nest Success Of Dabbling Ducks In A Human-Modified Prairie: Effects Of Predation And Habitat Variables At Different Spatial Scales, Jaime E. Jimenez

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Nest success of dabbling ducks in the Prairie Pothole region of North America has been declining for the past 40 years in parallel with declines in duck populations. Low nest success seems to result from the combination of an extremely fragmented breeding ground in a human-dominated landscape with an abundant and expanding community of generalist nest predators. Studies that examined variables associated with nest vulnerability to predation have produced contradictory results, likely because of simplistic approaches, lack of spatio-temporal replication, use of artificial nests, and the effect of confounding variables. I attempted to clarify the equivocal findings of previous studies …

Modeling Habitat Attributes Of Cavity-Nesting Birds In The Uinta Mountains, Utah: A Hierarchical Approach, Joshua J. Lawler

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Birds may have the ability to view their environments at a wide range of spatial scales; accordingly, they may make habitat-selection decisions at multiple spatial scales. I investigated the implications of hierarchy theory and a landscape perspective on nest-site selection in cavity-nesting birds in the Uinta Mountains in northeastern Utah. I used three different approaches to address the concept of a multi-scaled nest-site selection process. First, I conducted an exploratory study in which I investigated nest-site selection at three spatial scales for Red-naped Sapsucker (Sphyrapicus nuchalis), Northern Flicker (Colaptes auratus), Tree Swallow (Tachycineta bicolor), and …

Ultraviolet-B Radiation: Effects On Pollen Of 34 Taxa, And Inheritance Patterns And Carryover Of Radiation Response In Arabidopsis, Javad Torabinejad

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Although considerable research has addressed effects of elevated ultraviolet-B (UV-8) radiation on vegetative plant structures and processes, the reproductive biology and patterns of inheritance of UV-B tolerance have received much less attention. I examined the effects of UV-B radiation on pollen of 34 taxa. I also addressed questions concerning the patterns of inheritance of UV-B tolerance in Arabidopsis thaliana and examined potential cumulative carryover effects of UV-B exposure through multiple generations of this species.

In the first study, a significant reduction in pollen germination occurred in only five species, but pollen tube growth in more than half of the species …

Multi-Scalar Spatial Modeling Of Northern Forest Dynamics: Foundations, Theories, And Applications, Don C. Bragg

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This dissertation describes the development and analysis of a new forest dynamics model. The NORTHern Woodland Dynamics Simulator (NORTHWDS) was designed to spatially model forest pattern and process for the northern Lake States, and to incorporate multiple spatial scales. While ecologically detailed, this stand table-based model is sufficiently parsimonious to be able to simulate 100s to 1000s of hectares for centuries. Processes like tree regeneration, growth, and mortality, herbaceous and shrubby competition, biogeochemistry, carbon cycling, edge effects, and climatic influences are incorporated in NORTHWDS. Wind disturbance and white-tailed deer browsing were also included …

Effect Of Blue Light And Temperature On Leaf Expansion, Stem Elongation, And Growth, Tracy A. O. Dougher

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Short height and high yield per unit energy in controlled environments are essential to the success of a food production system for spaceflight. Temperature and light quality can be manipulated in controlled environments to reduce plant height and increase yield. Although the effects of temperature on height and yield are well studied at ambient CO₂, temperature effects at elevated CO₂ with a hydroponic root zone are not well characterized. We studied soybean yield and height under two lamp types over a broad range of temperatures. Temperature had little effect on yield or height, but lamp type had …

The Effects Of Salmon Availability, Social Dynamics, And People On Black Bear (Ursus Americanus) Fishing Behavior On An Alaskan Salmon Stream, Danielle K. Chi

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The primary goals of this research were to investigate 3 ecological factors influencing black bear (Ursus americanus) foraging behavior on an Alaskan salmon (Oncorhynchus spp.) stream: fish availability, social dynamics, and human activity. Over 900 observation hours were logged at 2 falls from July 1-September 1 1993-1995; the lower falls were open to public for wildlife viewing, but the upper falls were restricted to research personnel.

In general, black bears responded to differences in fish accessibility on both spatial and temporal scales. All years of the study, 3 indices of bear activity (bear minutes, bear numbers, bout …

Hydrogeomorphic Factors Influencing Clonal Recruitment Of Cottonwoods In Mountain Valleys, Michael D. Roberts

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Riparian cottonwoods (populus spp.) are keystone pioneer species that contribute to critical streamside and in-stream habitats, water quality, and aesthetic and recreational value. Land use and river regulation have caused a widespread reduction in the extent and regeneration of this genus. The majority of research on Populus species' reproduction has examined seedling recruitment that dominates in wide alluvial valleys. In contrast, I evaluated reproductive strategies of Populus angustifoliain mountain valleys. Research was conducted in northern Utah on the Little Bear River, a gravel-bedded stream that flows north out of the Bear River Range onto deposits of Ancient Lake …

Effects Of Safflower (A Spring Crop), And Wheat Planting Date On Controlling Jointed Goatgrass (Aegilops Cylindrica) In Winter Wheat, Caleb Dale Dalley

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

To improve management and control of jointed goatgrass (Aegilops cylindrica Host.) on traditional winter wheat (Triticum aestivum L.) cropland, a better understanding of the effects spring crop and wheat planting date have on weed populations and wheat yield is needed. A study of the effects of safflower (a spring crop) and wheat planting dates (early vs late) was conducted over a 2-yr period. Long term effects will be examined over a 5-yr period. The effects these treatments had on yield, weed seed contamination, jointed goatgrass population density, and soil seedbank concentration were measured. Two identical experiments were initiated, …

Influence Of Type Of Supplemental Carbohydrate On Ruminal Responses And Methane Output From Ruminants Consuming Low-Quality Forage, Raul J. Lira

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

In a completely randomized design with a factorial arrangement, three energy supplements and two species (cows and ewes) were evaluated in two identical experimental periods: gestation and lactation. The three supplement treatments were a control, barley, and sugar beet pulp (SBP). The basal diet was tall wheatgrass straw (5.52% CP).

Forage and total dry matter intake (FDMI and TDMI, respectively) interacted (P=.04) with species, supplements, and physiological stages.

An interaction of physiological stage and sampling time occurred for pH. Supplement and sampling time interacted for butyric acid proportion and total VFA concentration.

Diet digestibility displayed an interaction between …

A Survey Of The General Public Assessing Public Attitudes Toward Animal Damage Control Management Policy, Douglas K. Reiter

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

A mail survey of randomly selected stratified U.S. households assessed general attitudes toward wildlife and specific concerns about wildlife damage management and the federal Animal Damage Control program. Respondents strongly supported federal government's role in ensuring public safety, engaging in public education, and continuing research into nonlethal control methods. Weaker support was found for lethal control of predators and crop depredators, and financial compensation for losses due to wildlife activities was generally opposed. Lethal methods of control were generally considered to be inhumane and nonlethal methods humane. When asked to rank the importance of factors to be considered when selecting …

Uptake And Transformation Of Trichloroethylene By Hybrid Poplar: Laboratory Studies, Julie K. Chard

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Trichloroethylene (TCE) was widely used as an industrial solvent and degreasing agent for most of the twentieth century. It is now a widespread groundwater contaminant. Phytoremediation may be a cost-effective cleanup method for TCE-contaminated soils and groundwater. Studies of environmental TCE fate are complicated by its volatility. The literature reports both significant and insignificant plant uptake of TCE. Conflicting findings may be due to differences in exposure level, conditions, and duration of the studies, or to experimental artifacts from laboratory systems.

This research quantified plant uptake and volatilization of TCE using a unique laboratory system. Hybrid poplar trees were exposed …

Avian Community Response To Fire In A Gambel Oak Woodland, Andreas Leidolf

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

I assessed avian communities of Gam bel oak (Quercus gambelii) woodland and surrounding habitats at Camp W. G. Williams State Military Reservation , Utah, during summer of 1993-1998. I used point counts and incidental observations to compile an avian checklist. I observed 100 species, accounting for one third of all birds known from Utah. Overlap in species composition among habitats was considerable, yet each habitat supported a distinct complement of common species.

I compared bird species composition, abundance, richness, and diversity before and after fire in burned and unburned Gam bel oak woodland using point counts. I also investigated how …

In Vitro Growth Of Muscle Satellite Cells Isolated From Normal And Callipyge Lambs, Beatriz T. Rodriguez

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The muscle hypertrophy of lambs expressing the Callipyge phenotype is possibly linked to characteristics of their muscle satellite cells. Therefore, characteristics (proliferation, fusion %, and protein accretion) of cultured satellite cells isolated from the longissimus muscle of Callipyge (n = 3) and normal (n = 3) lambs were compared in this study. In the first experiment, we tested whether or not the lll proliferation rates differ for satellite cells isolated from Callipyge or normal sheep when cultured in the presence of different serum types (horse, normal lamb, or Callipyge lamb). The average population doubling time (PDT, h) during log phase …

Interaction Between Winter Dominance And Territory Defense In Male Pronghorn Antelope, Antilocapra Americana, Charles William Gunnels Iv

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

In a territorial population of pronghorn from Antelope Island, UT, interaction between male dominance and territory defense was examined. High-ranking males were more likely to defend territories. Closely ranked animals engaged in more dominance interactions than distantly ranked individuals, and middle-ranked animals were involved in disproportionately more interactions than either high- or low-ranking animals. Large males possessed large horns and prongs as well as small cheek patches. Results from a factor analysis suggested that large males defended territories with a high density of sage. However, in this study, we did not observe pronghorn feed on sage during the territorial season. …

Growth Of Clostridium Sporogenes Pa3679 In A Vacuum-Packaged Meat-Vegetable Product, Julie M. Racz

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Clostridium sporogenes PA 3679 spores were inoculated into a meat-vegetable mixture before extrusion, cooking, and vacuum packaging into "stewsticks" to simulate Clostridium botulinum growth. The experiment was a 3 x 5 x 2 x 3 factorial which determined the influence of pH, water activity, initial spore load, and storage period on spore survival. Spore levels decreased throughout storage for all treatments. Spore levels decreased linearly (P = 0.02) as water activity increased, in samples that were heated to kill vegetative cells and activate spores. Other significant interactions of heat-treated samples were observed with inoculum level (P < 0.01) and storage time (P < 0.01). Spore levels in stored products were also significantly affected by water activity * inoculum level (P = 0.03), pH * time, water activity * time (P = 0.01), inoculum level * time (P < 0.01), and water activity * inoculum levels * time (P < 0.01). The interaction between pH * water activity * time tended towards significance (P = 0.06). Most probable number estimates in nonheated samples accounted for naturally occurring viable cells and spores, and added spores and were significantly affected by the main effects of inoculum level (P < 0.01) and time (P < 0.01). The two-way interactions of water activity * inoculum level (P = 0.04), pH * inoculum level (P < 0.01), water activity * time (P < 0.01), and three-way interaction of pH * inoculum level * time (P = 0.03) were significant. Spore levels approached 10², or less …

Influence Of Carbohydrate Starvation On The Culturability And Amino Acid Utilization Of Lactococcus Lactis, Mark R. Stuart

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Lactococci are widely used in the cheese industry as a starter culture. Starter cultures face carbohydrate starvation due to the absence of a fermentable carbohydrate in the cheese curd after pressing. Starvation leads to a decreased ability to synthesize ATP, generate a proton motive force, and accumulate nutrients necessary to maintain viability. The aim of this work was to investigate the culturability of lactococci grown with and without lactose in a chemically defined medium, and to define the metabolic changes that occur during carbohydrate starvation.

Lactose metabolism provided energy for logarithmic phase growth and greater cell density in L. lactis …

Studies On The Utilization Of Deboned Trout (Oncorhynchus Mykiss) Frames In Fish Snack, S. Muralidharan

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Snack food development studies were conducted to iii utilize trout (Oncorhynchus mykiss) frames, a by-product of the filleting operation, using extrusion and conventional technology. Twin screw extrusion studies were conducted to study the effect of fish mince, non-fat dry milk, process temperature, and moisture content on the physicochemical properties of the extruded snack food. Response surfaces were plotted to understand the effects of the independent variables on dependent variables such as bulk density, expansion ratio, shear strength, and water absorption index. Quadratic models expressed the relationship between the dependent and independent variables.

Based on the extrusion studies, conditions …

The Development Of Pediococcus Species As Starters For Mozzarella Cheese, Shelby L. Caldwell

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Bacteriophage infection of Streptococcus thermophilus is a growing concern in the mozzarella cheese industry. One method to control this problem may be to replace S. thermophilus with a starter coccus from a different genus of lactic acid bacteria. This work evaluated the possibility of using genetically modified Pediococcus spp. for this approach. Electroporation was used to introduce genes for lactose utilization from Lactococcus lactis into strains of P. acidilactici and P. pentosaceus. The resulting lactose-positive transformants, P. acidilactici SAL and P. pentosaceus SPL-2, rapidly reduced the pH of lactose broth, accumulated [¹⁴C]lactose at a rate higher than …

Methanethiol And Cheddar Cheese Flavor, Benjamin Dias

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The use of slower acid-producing starter bacteria for the production of lower fat Cheddar cheese has lead to milder flavor Cheddar cheeses that lack intense Cheddar notes. The metabolism of methionine leads to the production of methanethiol, which is one of the desirable Cheddar cheese flavor compounds. The influence of NaCl and reduced pH was determined for aminopeptidase, lipase/esterase, and methanethiol-producing capability in selected lactic acid bacteria and brevibacteria in simulated cheese-like conditions. The activity of each enzyme decreased with NaCl addition and pH reduction to approximate a Cheddar cheese environment (5% NaCl and pH 5.2).

The mechanism for methanethiol …

A Study Of The Effects Of Proteolytic Adjunct Culture On The Physical And Functional Properties Of Low-Fat Mozzarella Cheese, Roxanne Stone

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

As fat is removed from Mozzarella cheese, the resulting increase in protein content causes the cheese to become tough, thus decreasing the desired physical characteristics of meltability and stretch. Low-fat (6% fat) Mozzarella cheese was manufactured with the addition of several levels of a Lactococcus lactis adjunct culture that was proteinase positive and lactose deficient in an attempt to improve these physical properties. During cheese manufacture, milk was acidified to pH 6.0, then inoculated with Lactobacillus helveticus and Streptococcus thermophilus. Experimental vats were also inoculated with either 0.25, 0.50, or 1.0% of the adjunct culture. Cheeses made with the …

A Product Development Study: Rainbow Trout Bologna, Marshall Dean Smith

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Mechanically deboned rainbow trout (Oncorhynchus mykiss) was analyzed and then used in texture studies. The meat contained a moderately low amount of fat (10% ± 2%, x ± SD). Pre-deboned meat had more calcium than deboned meat (P < 0.001). Sausages were made of fish and various non-meat ingredients including egg whites, collagen, soy protein isolate, starch, cellulose, and wheat gluten. Adhesiveness, cohesiveness, hardness, shear and springiness of the cooked sausages were measured to describe texture. The data were fit to linear and quadratic models. Adhesiveness data did not fit the model (F(6,50)=1.1, P > {F{=0.37). A combined response model predicted formulations for fish sausage that would closely duplicate the texture of commercially available processed meats. A thermal model was developed that helped verify the thermal properties of rainbow trout. Thermal conductivity was measured (k == 0.48 W/m·K) and specific heat was calculated (C_p= 3200 J/kg·K).

Heat-Stable Extracellular Enzymes Of Pseudomonas, Ramarathna Koka

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Psychotrophic bacteria produce heat-stable lipase, protease, and phospholipase. Pervious studies indicate the production of multiple enzymes in several strains of Pseudomonas fluorescens, but conclusive evidence is lacking.

The influence of culture conditions on the production and thermostability of phospholipase, protease, and lipase was investigated in 17 raw milk and environmental isolates. Production and thermostability of the enzymes were influenced by strain, stage of growth, and the culture medium. Cross-reactivity of antibodies raised to a purified protease and a commercial lipase indicated the immunological diversity of the enzymes.

Protease purification was undertaken to investigate the production of multiple proteases within a …

Utah's Rural Communities: Planning For The Future, Judith A. Kurtzman

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Two of the biggest concerns facing communities in the Intermountain West are the dichotomies of rapid growth and development as opposed to economic decline and stagnation. Numerous strategies have been developed by social and economic scientists to help communities manage the many problems associated with these concerns. One strategy recommended by many researchers and used by numerous communities to stabilize their economies is economic diversification. For many rural communities in Utah, tourism and recreation have been used as part of that diversification effort. Recreation and tourism also play a role in the dichotomies of rapid growth and development by often …

The Reproductive Biology And Edaphic Characteristics Of A Rare, Gynodioecious Saxifage: Saxifraga Bryophora Var. Tobiasiae (Saxifragaceae), Kimberly Pierson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

I examined the reproductive biology and general ecology of Saxifraga bryophora var. tobiasiae, a rare saxifrage endemic to the West Salmon River Mountains of central Idaho. Saxifraga bryophora var. tobiasiae combines asexual reproduction via bulbils with a sexual mixed-mating system. Flower production occurred in 1996 only, whereas bulbil production occurred in 1995, 1996, and 1997. Bulbil production precedes floral bud formation and is the dominant form of reproduction. When flowering occurs, outcrossing is promoted by protandry and the gynodioecious mating system found in all populations. No autogamous or agamospermous seed set was observed in either female or hermaphrodite flowers, …

Efficacy Of Guard Llamas (Lama Glama) In Reducing Canid Predation On Domestic Sheep, Laurie E. Meadows

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Predation, especially by canid predators, is a significant cause of sheep loss for many producers. In recent years, the use of llamas to protect sheep from predators has gained recognition as a depredation control method. I conducted a field experiment to test the effectiveness of llamas in reducing canid predation on domestic sheep. Twenty-one llamas were placed with Utah sheep producers. Data collected from these flocks over 20 months were compared to similar data collected from flocks without llamas. Comparisons between treatment and control flocks included (1) proportion of flocks with losses to predators, (2) mean predation rates on ewes …

Influence Of Grazing, Fire, And Rainfall Regime On Plant Species Dynamics In An Ethiopian Perennial Grassland, Michael J. Jacobs

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The dominant habitat-type of Omo National Park (ONP), Ethiopia, is grassland. This grassland supports a variety of wild herbivores and indigenous people; the latter hunt large herbivores for subsistence or graze their domestic livestock in the Park. Therefore, an understanding of grassland dynamics is a high priority for ONP management. Grazing and fire are major factors influencing species composition and vegetation change in East African grasslands. Rainfall regime, in turn, can influence both grassland response to grazing and fire. The ONP grasslands occur along a rainfall gradient ranging from subhumid to semiarid. Research objectives were to: (1) test the Milchunas, …

Influence Of Commercial Starter Media On Biochemical Characteristics Of Lactococcus Lactus, Norman Bart Devries

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Five strains of Lactococcus lactis were inoculated individually into six commercial bulk set growth media, 11% non-fat dry milk (NDM), and Elliker's broth. After growth in each medium the strains were tested for rate of acid production, and activities of proteinase, aminopeptidase, and lipase/esterase. Growth in commercial starter media significantly influenced acid production rate (P = 0.040), aminopeptidase activity (P < 0.0001), and lipase/esterase activity (P < 0.0001) .

For selected strain/media combinations, the duration of induced aminopeptidase and lipase/esterase activity was followed. The chosen strains were grown in selected commercial bulk set media, reinoculated into 11% NDM, and enzyme activity was examined for five successive …

Heat-Induced Gelation Of Ultrafiltered Whole Milk Concentrate And Product Applications, Hector Alejandro Solorio

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The heat-induced gelation properties of ultrafiltered (UF) whole milk concentrate were studied under different physical and chemical conditions. total solids concentration, homogenization pressures, heating temperatures, and heating times were found to have a positive correlation with gel strength. The addition of calcium chloride, sodium chloride, or trisodium citrate produced gels of higher strengths and textural properties than the gels obtained with non-salt-treated concentrate. Calcium chloride produced the strongest gels with a cheese-like texture and poor spreadability. Sodium chloride produced gels of intermediate strength with a firm, elastic texture and poor spreadability. Trisodium citrate produced the softest gels with a smooth, …