Life Sciences Commons^™

Impact Of Climate Variability On The Frequency And Severity Of Ecological Disturbances In Great Basin Bristlecone Pine Sky Island Ecosystems, Curtis A. Gray

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Many high elevation conifer species, including high elevation five needle pines, are declining throughout western North America. Warming temperatures, mountain pine beetle, white pine blister rust and alteration of naturally occurring fire regimes represent an interactive set of circumstances leading to greater risk. The loss of these treeline pines can detrimentally impact biodiversity and valuable ecosystem services including wildlife habitat, watershed and soil protection, aesthetics and recreation. Great Basin bristlecone pine ecosystems are naturally highly fragmented because of their elevational requirements. However, they may become even more fragmented due to combined impacts of warming temperature, insects and diseases listed above. …

The Influence Of Wind Energy Development On Columbian Sharp-Tailed Grouse (Tympanuchus Phasianellus Columbianus) Breeding Season Ecology In Eastern Idaho, Matthew C. Proett

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The Columbian sharp-tailed grouse (Tympanuchus phasianellus columbianus; CSTG) has experienced range-wide population declines, primarily as a result of habitat loss or degradation, and currently occupies <10% of its historic range. Expansion of wind energy developments across the remaining occupied CSTG range has been identified as a potential threat to the species. To assess the potential influence of wind energy development of CSTG breeding season ecology, I captured and radio-marked 135 female CSTG drugin 2014-2015 at leks located between 0.1-13.8 km from wind turbines in restored grassland habitats. Using radio-telemetry, I monitored 147 nests and 68 broods and developed models to assess the influence of wind turbines, roads, habitat features temporal factors, and precipitation on CSTG nest site selection, nest survival, brood success, and chick survival. Female CSTG in my study selected nest sites in grassland habitats where >30% of the canopy cover in the nesting core use area was composed of forbs (i.e., broadleaf plants). The strength of selection for this habitat type increased as its availability increased on the landscape. Nest survival increased with higher visual obstruction readings (i.e., concealment) at the nest bowl and in grassland habitats where forb cover exceeded 30% in the nesting core use area. I did not detect an influence of wind turbines or …

Effects Of Changing Environments On Survival Of A Widely Distributed Ungulate, S Andrew Sims

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Wildlife species distributed over large areas of land inhabiting varying environments are experiencing shifts in their home ranges due to human expansion and climate change. As these species home ranges shifts out of familiar, critical habitat they are forced to interact with novel environments, which in turn affects the species population demographics. In order to manage and conserve these species accordingly, specifically in a time of large-scale change, it is imperative that we add to current understandings of how they interact with various environments. Furthermore, frequently generating short-term predictions of demographic drivers will allow for conservation and management insight that …

Effects Of Gestational Dietary Intake On Calf Growth And Early Feedlot Performance Of Offspring, Jose M. Gardner

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Fetal programming is a relatively new and quickly growing field of research in the livestock industry. The concept of fetal programming is simply defined as the effects a change in maternal nutritional intake has on offspring, whether it be a genetic or physical change. The intention of this study was to specifically look at the effects of nutrient restriction of cows during the second trimester of gestation on the growth and performance of the resulting calves.

In this study, thirty-two cows of predominantly angus influence from the Utah state university herd were chosen, naturally bred to a pure bred angus …

Precision Drought Stress In Orchards: Rootstock Evaluation, Trunk Hydration And Canopy Temperature, Lance V. Stott

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Tree fruit crops are of high value, but use a lot of water. Precision irrigation has the potential to save water while simultaneously improving crop quality. The timing and method of precision water stress in various tree fruit crops has been widely studied. However, in order to successfully employ precision irrigation methods in orchards, an accurate measurement of tree water status is required. Currently, stem water potential is the preferred indicator. However, this measurement is tedious and cannot be automated. Because measurements must be taken near solar noon (approximately 1:30 PM MDT in the summer in northern Utah), the number …

Intentional Mentoring Through 4-H: The Role Of 4-H In A Successful Mentoring Program Between Youth And Adults, Emily Ann Shepperd

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

4-H Youth and Families with Promise (4-H YFP) is a one to one youth mentoring program that aims to help youth obtain skills that will help them to be successful. The purpose of this research was to determine if any positive outcomes were shown of youth participating in 4-H YFP. Positive outcomes were identified as peer social competence, greater ability to make positive choices, the development of effective communication skills, building connections, and contributing to the community. Results show that these outcomes positively increased among youth participants in the 4-H YFP program- but the changes were too small to be …

Conservative Tryptophan Mutations In Protein Tyrosine Phosphatase Ptp1b And Its Effect On Catalytic Rate And Chemical Reaction, Teisha Richan

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Protein-tyrosine phosphatases (PTPs) catalyze the hydrolysis of phosphorylated tyrosines by a 2-step mechanism involving nucleophilic attack by cysteine and general acid catalysis by aspartic acid. In most PTPs the aspartic acid resides on a flexible protein loop, consisting of about a dozen residues, called the WPD loop. PTP catalysis rates span several orders of magnitude, and differences in WPD loop dynamics have recently been show to correlate with the rate of enzymatic catalysis. The rate of WPD loop motion could possibly be related to a widely conserved tryptophan residue on the WPD loop. Therefore, point mutants were made in PTP1B …

Effect Of N-3 And N-6 Polyunsaturated Fatty Acids On Inflammation, Tao Xu

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Intake of polyunsaturated fatty acids (PUFA) has changed drastically in the past century in the American diet has received attention due to potential effects on chronic inflammation-related metabolic diseases. In this project, the effects of dietary PUFA content and the n-6 to n-3 ratio on inflammatory responses in the acute and chronic inflammation models were evaluated. The PUFA content was modified on a Western diet background to deliver both n-6 and n-3 intakes at the 10^th and 90^th percentile of the population in the United States, and models of acute and chronic inflammation were tested in mice model. …

Spatial Ecology Of Coyotes And Cougars: Understanding The Influence Of Multiple Prey On The Spatial Interactions Of Two Predators, Peter J. Mahoney

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The coyote (Canis latrans) has expanded throughout much of North America over the past century following the regional extirpation of apex predators. These highly adaptable canids can occupy a variety of landscapes from the rainforests of Central America to the dense, human-dominated urban centers of the United States. As a generalist predator, coyotes can capitalize on a variety of food resources, including anthropogenic subsidies such as domestic livestock and food tailings at landfills. These tendencies often bring coyotes in direct conflict with humans, forcing managers to consider mitigation strategies ranging from the targeted removal of problem individuals to …

Analysis Of Beef Steaks Of Varying Usda Quality Grades And Thicknesses Cooked On Low And High Grill Surface Temperatures, Tonirae Gardner

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The objective of this project was to analyze the thermodynamics (thermal conductivity and diffusivity as well as protein denaturation) and physical properties (percent expressible moisture, cooking loss, change in steak thickness, shear force, texture profile analysis and rheological behavior) of beef steaks of different USDA quality grades (Upper 2/3 Choice and Select), thicknesses (thick and thin), and grill surface temperatures (high and low) cooked to the same internal degree of doneness to determine if a specific set of cooking parameters would create a profound difference in the eating characteristics, described by the tenderness and juiciness of cooked beef strip steaks. …

Nitrogen Excretion Of Lactating Dairy Cows Fed An Alfalfa Hay- Or Birdsfoot Trefoil Hay-Based High-Forage Diet, Mohammad Ghelich Khan

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Legumes that contain condensed tannins (CT) may have lower protein degradability than alfalfa. The present study investigated the effects of feeding birdsfoot trefoil (Lotus corniculatus L.) hay on lactation performance and N utilization. Eight multiparous Holstein cows in mid lactation (150 ± 22.3 d-in-milk) were randomly assigned to 1 of 2 rations [alfalfa hay-based TMR (AHT) or birdsfoot trefoil hay-based TMR (BFTT)] in a crossover design with 2 experimental periods. Each experimental period lasted 16 d (14 d of adaptation and 2 d of total collection), and the 2 experimental periods were separated by a 7-d washout period. In the …

Increasing Student Engagement And Knowledge Retention In An Entry-Level General Nutrition Course With Technology And Innovative Use Of A Graduate-Level Teaching Assistant, Minhee Kang

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Blended-design courses integrate both face-to-face and online learning. This thesis discusses the use of three teaching innovations and their effect on student engagement and course satisfaction in a blended-design nutrition course. The three teaching innovations include 1) a web-based learning platform, called Connect (published by McGraw-Hill Education) 2) other easily accessible technological tools (such as Google+), and 3) higher-level use of a graduate-level teaching assistant.

Another form of web-based learning platform, Mastering, published by Pearson Education, was use previously in the course. However, students, especially those earning the highest grades in the course, did not see value in completing these …

Molecular And Physiological Mechanisms Of Toxin Resistance In Toad-Eating Snakes, Shabnam Mohammadi

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Many plants and animals are defended by toxic compounds, and circumvention of those defenses often has involved the evolution of elaborate mechanisms for tolerance or resistance of the toxins. Toads synthesize potent cardiotonic steroids known as bufadienolides (BDs) from cholesterol and store those toxins in high concentrations in their cutaneous glands. Those toxins protect toads from the majority of predators, including most snakes that readily consume other species of frogs. BDs exert their effect by inhibiting ion transport by the Na⁺/K⁺-ATPase (NKA). This ubiquitous transmembrane enzyme consists of a catalytic alpha-subunit, which carries out the enzyme's …

The Role Of The Fatty Acid Signaling Pathway In Dietary-Induced Obesity, Melissa N. Nelson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

In recent years, dietary fat has been shown to be capable of activing taste receptor cells in the tongue. Fatty acids (FAs), which act as the chemical cue and are found in dietary fat, activate a cellular signaling pathway that results in a unique signal being sent to the brain that is then interpreted as the taste of fat. One important element in this pathway is the ion channel TrpM5. It is responsible for depolarizing the taste cells that are activated by fatty acids; depolarization is an essential step in cellular response, making TrpM5 essential in the functioning of the …

Spatial And Behavioral Patterns Of Captive Coyotes, Jeffrey T. Schultz

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Environmental enrichment is a technique used at many captive animal facilities that can improve the well-being of their animals. It seeks to enhance habitat features and promote natural behavior by providing a variety of practical ways for captive animals to control their environmental settings, especially during stressful circumstances. Enclosure features, such as shelter structures, are one tool that promotes wild behavior by adding complexity to an enclosure’s physical environment. Enrichment efforts for captive wildlife are most effective when they are specialized to the biological needs of the animals. Human activity may alter captive animal behavior and utility of enclosure features, …

Sclerocactus Wetlandicus: Habitat Characterization, Seed Germination And Mycorrhizal Analysis, Kourtney T. Harding

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The Uinta Basin hookless cactus (Sclerocactus wetlandicus) is a threatened species native to Eastern Utah. The cactus is found in a landscape highly disturbed by non-renewable energy production. To understand the environmental conditions that support natural growth of this cactus, we asked what types of plants were present in the same areas as the cactus, and if the types of plants were different in environments that were disturbed. From our assessment, we determined that the types of plants present in disturbed areas were drastically different from those present in undisturbed locations. Areas previously used for energy production are …

To What Extent Might Beaver Dam Building Buffer Water Storage Losses Associated With A Declining Snowpack?, Konrad Hafen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Dams built by North American Beaver create natural water storage and slow water as it moves through streams. In portions of streams with beaver dams, these effects have been observed to decrease the peak magnitude of floods and increase base flow during annual summer droughts. In the western United States changes to streamflow patterns have been observed in recent decades with large spring floods coming earlier in the year, causing annual summer droughts to start earlier and last longer. These changes are linked to decreasing snowpack which acts as the most significant natural water storage reservoir by holding onto precipitation …

Mechanism Of Substrate Reduction By Nitrogenase, Nimesh Khadka

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Nitrogen (N) is a vital element of life and the main component of chemical fertilizer. The industrial Haber-Bosch process fulfills the demands of today’s nitrogen need and is therefore considered as one of the major scientific breakthroughs of the last century. However, the Haber-Bosch process operates at very high temperature and pressure, and requires fossils fuels to drive the reaction, making it an energy expensive process. The energy demand for this process accounts for almost 3% of the total global energy consumption. In addition, the rapid population growth, economic development and depletion of limited non-renewable fossil fuels have already created …

The Behavior And Ecology Of Cursorial Predators And Dangerous Prey: Integrating Behavioral Mechanisms With Population-Level Patterns In Large Mammal Systems, Aimee Tallian

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Driving into Yellowstone National Park for the first time is a moving experience. Gazing over the sweeping landscapes, seeing a geyser erupt 80 feet into the air, and having your first ‘wildlife encounter’, whether that be a 2 ton bull bison aggressively wallowing on his dirt mound, snorting and kicking up dust, or watching a pack of 6 wolves move through a valley off in the distance, pausing to howl in search of their companions. Yellowstone staff wishes to manage our park in a way that preserves these remarkable experiences. In order to effectively manage this dynamic ecosystem, it is …

Understanding The Mechanisms Of Insecticide Resistance In Phlebotomus Papatasi And Lutzoymia Longipalpis Sand Flies (Diptera: Psychodidae: Phlebotominae), David Denlinger

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Sand flies, like mosquitoes, ticks, fleas, and lice, transmit pathogens that cause disease in humans. Leishmaniasis, caused by pathogens transmitted by sand flies, kills tens of thousands of people every year. Insecticides have been used to control sand flies, but there is evidence of insecticide resistance in populations of sand flies around the world. The goal of this dissertation was to develop tools to maintain sand flies in the laboratory, develop the ability to identify insecticide-resistant populations of sand flies, and to investigate the genetic mechanisms of how sand flies become resistant to insecticides. I began by comparing live animal …

Effects Of Variable And Changing Environments On Demography: Inferences From A Lesser Snow Goose Colony, David T. Iles

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The mean and variability of environmental conditions have changed as a result of human activity, and continued changes are predicted. The strongest effects on natural populations will often be channeled through species interactions, as shifts in species range limits and life cycle schedules will shift in relation to each other. These changes will often impact rates of survival, growth, and reproduction simultaneously, and these effects will likely differ across habitats.

In chapter 2, I used mathematical modeling and computer simulations to investigate the evolutionary significance of increasingly variable environments, and examine how evolutionary pressures change when multiple vital rates are …

The Performance Of A Bioenergetics Model In A System With An Abundant Population Of Salmonids: A Case Study Of Cutthroat Trout In The Logan River, Utah, Martha L. Jensen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Widespread habitat degradation and fragmentation has significantly altered the distribution and abundance of salmonids across the Western United States. To effectively conserve these fish, managers need tools to evaluate habitat quality in physically diverse streams and watersheds. Traditionally, habitat assessment for stream fish has focused on the physical characteristics of sites. Thus, such research has often overlooked important biological factors, such as the availability of prey or the presence and abundance of competitors or predators. In recent years, however, researchers have considered habitat from both physical and biological dimensions.

Bioenergetics models offer a way to combine the both the biotic …

Foraging Ecology Of Mountain Lions In The Sierra National Forest, California, Bradley C. Nichols

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

We conducted this research to gain insight into mountain lion (Puma concolor) prey composition in the Sierra National Forest of California. Managers in the region are concerned with both causes of declines and inability to increase fisher (Pekania pennanti) populations. Research has shown that mountain lions are a threat to fishers due to direct predation of this forest specialist. We radio-collared 5 adult mountain lions in order to determine prey composition and kill rates. As expected, mountain lions selected primarily for mule deer (Odocoileus hemionus). However we did detect other prey such as gray …

Predicting The Impact Of A Northern Pike (Esox Lucius) Invasion On Endangered June Sucker (Chasmistes Liorus) And Sport Fishes In Utah Lake, Ut, Jamie Reynolds

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Invasive species introductions are associated with negative economic and environmental impacts, including reductions in native species populations. Successful invasive species populations often grow rapidly and a new food web structure is established. The ability of invasive species to outcompete and prey upon native species are two characteristics that make them a leading cause of fish extinctions in North America.

Northern pike (Esox lucius; hereafter pike) are voracious ambush top predators \native to the upper Midwest and Mid-Atlantic regions of the lower 48 United States, Alaska, and southern Canada. Pike have been spreading across the Intermountain West and Pacific …

Evaluating Habitat-Based Niche Requirements And Potential Recruitment Bottlenecks For Imperiled Bluehead Sucker (Catostomus Discobolus), Bryan C. Maloney

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Changes to rivers that alter physical and thermal habitat may cause fish population abundance to decline, due to fewer individuals maturing and entering the adult population. The Weber River has become highly degraded with many dams and diversions altering fish habitat, river volume, velocity, and temperature, and limiting movement between reaches. Bluehead suckers (Catostomus discobolus) occupy only 47% of their historical range and the genetically-distinct Weber River (northern UT) population is declining and contains few young, juvenile fish. My objectives were to determine whether spawning and rearing habitat available in the Weber River may be limiting bluehead sucker …

Interactions Between Plant Water-Stress And Neonicotinoid Insecticides On Spider Mite Infestations In Corn, Alice Ruckert

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Spider mites (Acari: Tetranychidae) are an important agricultural pest of many crops and landscape plants. They can reproduce rapidly and quickly develop resistance to many pesticides, making them difficult to manage. Plant water-stress and high temperatures promote spider mite infestations, while spider mite outbreaks can also result from neonicotinoid insecticide applications. Drought is predicted to increase in the Intermountain West due to increases in temperature and reduced frequency of precipitation events in the region, and neonicotinoids are currently one of the most widely used classes of insecticides in field crops. I studied the interactive effect of these two simultaneously occurring …

Evaluating The Effectiveness Of Utah Farm Field Days, Paige Wray

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Utah farm field day events seek to increase agricultural literacy among elementary students. Although these events are occurring statewide, no formal evaluation has been conducted to determine student increases in agricultural literacy related to these events. The purpose of this study was to evaluate two such events to see what students knew about agriculture before they attended the farm field day, what they wanted to learn about concerning agriculture, and what they learned after attending the event. Results showed that these children were below average for expected grade level understandings or agricultural awareness before the event. However, after the event, …

Direct And Indirect Effects Of Climate Change On Plant Populations And Communities In Sagebrush Steppe, Andrew R. Kleinhesselink

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Rapid climate change presents humanity with a number of big problems. Foremost among these is the sad fact that the climate we will pass on to our children will likely be nothing like the climate that we inherited from our parents. Ecologists have collected solid evidence that climate change has already begun to affect the living things around us and the ecosystems humans depend on. Unfortunately, predicting the future effects of climate change on life on earth is not easy. We focused on three research goals as part of an effort to improve our ability to predict how plants and …