Life Sciences Commons^™

Disturbance Ecology And Vegetation Dynamics At Varying Spatial And Temporal Scales In Southern Rocky Mountain Engelmann Spruce Forests, R. Justin Derose

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

High-severity disturbances are the primary drivers of Engelmann spruce-subalpine fir ecosystems in the southern Rocky Mountain. Recently, an unprecedented, landscape-wide (at least 250 km2) spruce beetle outbreak killed virtually all the Engelmann spruce on the Markagunt Plateau in southwestern Utah, USA. Results from dendroecological analyses suggested the combination of antecedent disturbance history and drought-driven stand development was responsible for creating suitable host conditions prior to the recent outbreak. Multiple and consistent lines of evidence suggested mixed- and high-severity fires shaped the development of the Markagunt Plateau. Subsequent stand development, influenced by species-specific differential tree-ring response to drought, resulted in the …

Investigating Methods To Reduce Black Bear (Ursus Americanus) Visitation To Anthropogenic Food Sources: Conditioned Taste Aversion And Food Removal, Kari D. Signor

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Conflicts between humans and black bears (Ursus americanus) jeopardize the safety of both humans and bears, especially when bears become food-conditioned to anthropogenic food sources in areas such as campgrounds. Interest in using non-lethal techniques, such as aversive conditioning, to manage such conflicts is growing. I conducted a captive experiment at The Wildlife Science Center in Minnesota and two field experiments in the La Sal Mountains, Utah, to investigate the effects of taste aversion conditioning using thiabendazole (TBZ) with a novel flavor cue and food removal on black bear food consumption and visitation to human food sources. In …

Herbicide, Salinity, And Flooding Tolerance Of Foxtail Barley (Hordeum Jubatum L.) And Desirable Pasture Grasses, Karl R. Israelsen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Research trials performed in the greenhouse compared the tolerance and response of Hordeum jubatum and desirable pasture grass species to herbicides, salinity, and flooding. Desirable grass species used in this study included: 'Fawn' tall fescue (Festuca arundinaceae), 'Garrison' creeping foxtail (Alopecurus arundinaceus), 'Palaton' reed canarygrass (Phalaris arundinacea), 'Climax' timothy (Phleum pratense), 'Alkar' tall wheatgrass (Thinopyrum ponticum), 'Potomac' orchardgrass (Dactylis glomerata), and 'Mustang' altai wildrye (Leymus angustus). Tolerance to herbicides, salinity, and flooding varied significantly among grass species. Herbicide tolerance was tested using four herbicides at five …

Seed Banks Of Sagebrush Communities Seeded With Crested Wheatgrass, Kevin L. Gunnell

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Crested wheatgrass (Agropyron cristatum [L.] Gaertn.) is one of the most commonly seeded exotic species in the western United States. Although many degraded Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis) plant communities have been seeded with crested wheatgrass during rehabilitation efforts, seed banks of these communities have not been characterized. I sought to characterize and explain the variation among 33 seeded communities in the northeastern Great Basin. Hierarchical clustering and principal components analysis identified four possible seed bank categories in these communities. Seed bank categories varied from high to low crested wheatgrass dominance. The crested wheatgrass-dominated category …

Effect Of Surface Stability On Core Muscle Activity During Dynamic Resistance Exercises, Brennan J. Thompson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The purpose of this study was to compare core muscle activity during resistance exercises performed on stable ground versus an unstable surface and to examine whether lifting at different relative intensities affects core muscle activity levels. Twelve trained men performed four different movements including the deadlift, back squat, military press, and curl. Surface electromyography (EMG) was utilized to assess the activity of the rectus abdominis, external oblique, transversus abdominis, and erector spinae muscles. Participants performed each movement under three separate conditions including standing on stable ground with 50% of their one repetition maximum (1-RM), standing on a BOSU balance trainer …

Consumer-Driven Nutrient Recycling In Arctic Alaskan Lakes: Controls, Importance For Primary Productivity, And Influence On Nutirient Limitation, Cody R. Johnson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

In lakes, fish and zooplankton can be both sources and sinks of nitrogen (N) and phosphorus (P) through the consumption of organic N and P, and subsequent excretion of bioavailable inorganic forms. These source/sink dynamics, known as consumer-driven nutrient recycling (CNR), may, in turn, control the availability of potentially limiting nutrients for algal primary production. In this dissertation I investigate the importance and controls of CNR as a source of inorganic N and P for primary production (Chapter 2). I then examine zooplankton CNR as a mechanism for increasing nutrient mean resident time (MRT) in the mixed layer of lakes …

Watershed-Scale Analysis Of Riparian Buffer Function, Molly Van Appledorn

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The ability of riparian buffers to filter undesirable nutrients from upland sources has long been recognized as an important ecosystem service for maintaining or improving water quality, and as a result, many land management strategies have been built around the preservation or restoration of buffer zones. Newly derived flow-path metrics have shown great promise as a way to assess riparian buffer function at the watershed scale but a thorough investigation of metric performance was necessary. The goals of this study were to: 1) test the independence of flow-path metrics from traditional metrics using a spatially extensive, independent sample of watersheds, …

The Regulation Of Epithelial Sodium Channels In Mammalian Taste Receptor Cells, Arian F. Baquero Gonzalez

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Nutrient recognition is one of the main physiological roles of the gustatory system. In mammals, it is well established that the taste of sodium salts is primarily mediated by sodium influx through the epithelial sodium channel. The epithelial sodium channel is a sodium-specific ion channel that is expressed across a wide range of transporting epithelia such as colon, kidney, and taste. In addition to its role as a salt taste receptor, sodium influx through the epithelial sodium channel is important systemically for maintaining sodium balance and blood pressure. Following our earlier work on the endocrine regulation of salt taste at …

Targeting Fat-Sensitive Pathways In Enteroendocrine Cells Using Nanoparticle-Mediated Drug Delivery, Bhavik P. Shah

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The current epidemic of obesity has been linked to an increase in fat intake associated with the Western diet. Nutrient-induced stimulation of enteroendocrine cells in the small intestine leads to the release of hormones that contribute to satiety and the control of food intake. In particular, ingested fat, specifically in the form of free fatty acids, is potent activator of enteroendocrine cells in the proximal small intestine. However, the underlying signaling cascade that free fatty acids initiate in these enteroendocrine cells, which leads to secretion of satiety hormones, is not known. In general, my research is focused on identifying nutrient-responsive …

Inducing A Normal Phenotype In Breast Epithelial Cells Using A Three-Dimensional Basement Membrane Extract Culture System: A Study On The Reversion Of Cancer, Ross H. Booth

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Experimentally, traditional developmental models and transgenic animals consistently underscore the importance of studying cell behavior in the correct tissue context. However, live animal experimentation is inherently complex, and systematic assessment of the effects of individual variables, such as cell shape and matrix compliance on cell behavior, is extremely difficult at best. Two-dimensional monolayer culture of key individual cell types has provided abundant, fundamental information on cell response, but cannot be used to show the normal phenotype of breast epithelial cells. Furthermore, their results often fail to translate into in vivo and clinical studies. It has been previously established that normal …

The Use Of Reverse Genetics To Clone And Rescue Infectious, Recombinant Human Parainfluenza Type 3 Viruses, Jason Peter Roth

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Reverse genetics is a discipline that involves the use of genetic manipulation and modification to study an organism's altered phenotype. In this study, infectious recombinant viruses were rescued from altered cDNA clones encoding the antigenome of human parainfluenza virus type 3 and the resulting phenotypes were examined. In one clone, the gene for the enhanced green fluorescent protein was inserted into the virus antigenome to be expressed during viral replication, resulting in infected cells emitting green fluorescence. Viral titers, mRNA replication, and genomic replication for the virus expressing the enhanced green fluorescent protein were reduced when compared to the human …

Application Of Electrified Fladry To Decrease Risk Of Livestock Depredation By Wolves (Canis Lupus), Nathan J. Lance

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Wolf (Canis lupus) predation on livestock can cause economic and emotional hardships for livestock producers, complicating the balance of wolf conservation with other human interests. New management tools that decrease risk of predation may offer additional flexibility or efficiency for both livestock producers and management agencies. I examined 1) the efficacy of electrified fladry compared to fladry at protecting a food source from wolves in captivity, 2) the efficacy of electrified fladry for reducing wolf use of pastures and preventing depredations, and 3) the applicability of electrified-fladry. In captivity I tested the reaction from 15 groups (46 wolves) …

Social Acceptability Of Conifer Control And Sagebrush Restoration In The Northern Rocky Mountain Region, Cameron G. Nay

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

In the past two centuries, woody plant species have increased in density and extent throughout the rangelands of North America. This encroachment generally has undesirable effects on hydrological function, forest resources, and plant community composition. Encroachment of Douglas-fir (Pseudotsuga menziesii) and ponderosa pine (Pinus ponderosa) into sagebrush communities is occurring in the Northern Rocky Mountain region. Removal and restoration treatments are often proposed to manage this issue, mainly prescribed fire, mechanical destruction, and/or herbicide use. Several contextual factors may affect public level of acceptability for such treatments. The issue frames used to present this problem to …

Evaluation Of Macroinvertebrates As A Food Resource In The Assessment Of Lotic Salmonid Habitat, Nicholas P. Weber

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Criteria used to characterize lotic salmonid habitat are often based on observed correlations between physical habitat characteristics and salmonid abundances. A focus on physical habitat features ignores other habitat components, such as an adequate supply of food that set the physiological limitations on salmonid growth and survival. This study outlines the development of a habitat assessment approach that focuses on how invertebrate food availability interacts with stream temperatures to determine salmonid growth potentials. Abundances of benthic and drifting invertebrate communities, stream temperatures, and juvenile steelhead trout (Onchorhynchus mykiss gairdneri) summer growth rates and abundances were measured within 10 …

Surgical Sterilization Of Coyotes To Reduce Predation On Pronghorn Fawns, Renee Seidler

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Coyote (Canis latrans) predation accounts for the majority of neonatal pronghorn (Antilocapra americana) mortality in many areas and may influence local population declines. Current techniques used to manage coyote predation on wildlife species generally focus on lethal control methods. However, these methods may be controversial to the general public. Coyote sterilization is an alternative predation control method which is more acceptable to the public and has been shown to be effective in reducing sheep predation. We hypothesized that surgical sterilization of coyotes may increase pronghorn fawn survival; in the same way it reduces coyote predation on …

Evolutionary Consequences Of The Introduction Of Eleutherodactylus Coqui To Hawaii, Eric Michael O'Neill

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The introduction of a species to areas outside its native range can result in ecological and genetic changes of evolutionary significance. The frog Eleutherodactylus coqui was introduced to Hawaii, from Puerto Rico, in the late 1980s and has lost genetic variation in mitochondrial DNA. The extent to which founder effects have influenced phenotypic variation in the introduced range is unknown. In this study I compared phenotypic variation in life-history traits, advertisement calls, and stripe patterns among introduced and native populations of the frog Eleutherodactylus coqui. I also conducted laboratory experiments to determine the influence of genetics and temperature on …

Patch-Scale Effects Of An Invasive Ecosystem Engineer On The Structure And Function Of A Eutrophic Stream, Samuel J. Hochhalter

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Recent theoretical and technological advances in ecosystem science have dramatically expanded the ways in which scientists can pursue and explore ecological questions. For my thesis research, I integrated the recent theoretical concept of organisms as ecosystem engineers with the relatively recent development of stable isotope tracer tests to ask the question: how does the invasive common carp affect stream ecosystem structure and function? To investigate the structuring role of carp, I measured autotroph seasonal distribution and abundance and macroinvertebrate seasonal abundance and diversity within two stream reaches in Spring Creek, Utah, USA; one with low carp biomass (LCB) and one …

River Network Structure: A Template For Understanding Predator-Prey Dynamics And Potential Anthropogenic Impacts, Catherine L. Hein

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

A landscape perspective is critically important for understanding community structure, particularly in systems dominated by migratory fauna. I aimed to understand how the structure of riverscapes in Puerto Rico mediates potential anthropogenic impacts, predator-prey interactions, and the migratory behavior of a diadromous species. I surveyed fishes and shrimps at sites throughout two watersheds, designed transplant experiments that investigated the role of natural barriers on predator-prey interactions, and developed models of shrimp migration specific to a particular river network. I did not detect an effect of anthropogenic changes to the landscape on fish and shrimp species distributions in two watersheds that …

Terrestrial Small Mammals From The Gamba Complex In Gabon: Distribution Patterns And Landscape Influences, Carrie J. O'Brien

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The small mammal communities of central Africa are not well understood, and the southwestern section of Gabon has not been previously surveyed except for some recent work in Monts Doudou. At five sites within the Gamba Complex we set out to 1) document the species of terrestrial rodents (Muridae) and shrews (Soricidae) weighing less than 100 g, 2) compare the community composition between inland and coastal sites, and 3) evaluate our sampling protocols. Using a combination of pitfall lines, Sherman live traps, and snap traps we captured 721 individuals of 12 rodent and 10 shrew species in 15,792 trap-nights. The …

Linking Space Use And Behavior In Clark's Nutcracker: An Explanation For Seasonal Variation In Space Use, Teresa J. Lorenz

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Clark's Nutcrackers (Nucifraga columbiana) are important seed dispersers for at least 10 species of conifer in western North America and are obligate mutualists for the subalpine tree, whitebark pine (Pinus albicaulis). Despite the important role they play in forest regeneration, space use by nutcrackers has not been formally studied. Several hypotheses exist to explain their year-round space use patterns. I tested one hypothesis that Clark's Nutcrackers migrate altitudinally between summer and autumn in one population in the Cascade Range, Washington. In 2006 and 2007, I compared seasonal differences in summer and autumn space use by 26 …

Prediction Of Protein Function And Functional Sites From Protein Sequences, Jing Hu

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

High-throughput genomics projects have resulted in a rapid accumulation of protein sequences. Therefore, computational methods that can predict protein functions and functional sites efficiently and accurately are in high demand. In addition, prediction methods utilizing only sequence information are of particular interest because for most proteins, 3-dimensional structures are not available. However, there are several key challenges in developing methods for predicting protein function and functional sites. These challenges include the following: the construction of representative datasets to train and evaluate the method, the collection of features related to the protein functions, the selection of the most useful features, and …

Sustaining The Allideghi Grassland Of Ethiopia: Influences Of Pastoralism And Vegetation Change, Almaz Tadesse Kebede

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The Allideghi Wildlife Reserve in the Amibara District of Afar Regional State, Ethiopia, has international significance for harboring endangered Grevy's Zebra and other wildlife dependent on grasslands. The reserve is increasingly used by pastoral people and their herds. Impacts of livestock on native vegetation include direct effects of grazing and indirect effects from livestock-facilitated dispersal of an invasive plant, Prosopis juliflora. The main research objective was to determine effects of pastoralism and vegetation change on prospects for sustaining the Allideghi Wildlife Reserve as grassland habitat for Grevy's Zebra. Methods included use of driving surveys to quantify resource use by …

A Comparative Study Of The Structural Features And Kinetic Properties Of The Mofe And Vfe Proteins From Azotobacter Vinelandii, Miguel Alejandro Pabon Sanclemente

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Biological nitrogen fixation is accomplished in the bacterium Azotobacter vinelandii by means of three metalloenzymes: The molybdenum, vanadium, and iron-only nitrogenase. The knowledge regarding biological nitrogen fixation has come from studies on the Mo-dependent reaction. However, the V- and Fe-only-dependent reduction of nitrogen remains largely unknown.

By using homology modeling techniques, the protein folds that contain the metal cluster active sites for the V- and Fe-only nitrogenases were constructed. The models uncovered similarities and differences existing among the nitrogenases regarding the identity of the amino acid residues lining pivotal structural features for the correct functioning of the proteins. These differences, …

Cognitive Inference And Resulting Behaviors In Response To Ambiguous Threat In The Coyote, Canis Latrans, Sarah Shawnee Dawson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

While antipredator strategies have been a focus of behavioral research for decades, scientists generally study the responses of prey toward overt, explicit threat. However, risk can also be significant when a threat is covert, such as when an ambush predator may be nearby or a secondary threat remains after a predator's departure. Little is known about the mechanism that prey use to assess risk in a predator's absence. Tests were conducted to determine the manner in which coyotes respond to these ambiguous threats. Specifically, I tested whether coyotes respond to prior anthropogenic activity that has occurred near their only food …

Effects Of Targeted Grazing And Prescribed Burning On Fire Behavior And Community Dynamics Of A Cheatgrass (Bromus Tectorum)-Dominated Landscape, Joel M. Diamond

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Studies were conducted to determine the effectiveness of using targeted grazing and prescribed burning as tools to reduce fire hazards and cheatgrass (Bromus tectorum) dominance on rangelands in the northern Great Basin. A field study, with four grazing-burning treatments (graze and no-burn, graze and burn, no-graze and burn, and no-graze and no-burn), was conducted on a B. tectorum-dominated site near McDermitt, Nevada from 2005-2007. Cattle removed 80-90% of standing biomass in grazed plots in May 2005 and 2006 when B. tectorum was in the boot (phenological) stage. Grazed and ungrazed plots were burned in October 2005 and …

Predicting The Growth Potential Of A Shallow, Warm-Water Sport Fishery: A Spatially Explicit Bioenergetics Approach, Samuel Kirk Dahle

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Capturing the range of fish consumption and growth potential of large, heterogeneous lentic systems can be challenging due to strong gradients in productivity, the diversity of habits types present, and in some cases, site-specific water quality issues. Cutler Reservoir (Utah, USA) displays a high degree of spatial and temporal variation in physical conditions and potential water quality limitations for fish, including high summertime water temperature and large, diel fluctuations in dissolved oxygen concentrations. The combination of bioenergetics modeling and GIS spatial analysis offers a promising interface for quantifying the fish consumptive and growth potential across a spatially and temporally heterogeneous …

Maintaining Population Persistence In The Face Of An Extremely Altered Hydrograph: Implications For Three Sensitive Fishes In A Tributary Of The Green River, Utah, Jared L. Bottcher

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The ability of an organism to disperse to suitable habitats, especially in modified and fragmented systems, determines individual fitness and overall population viability. The bluehead sucker (Catostomus discobolus), flannelmouth sucker (Catostomus latipinnis), and roundtail chub (Gila robusta) are three species native to the upper Colorado River Basin that now occupy only 50% of their historic range. Despite these distributional declines, populations of all three species are present in the San Rafael River, a highly regulated tributary of the Green River, Utah, providing an opportunity for research. Our goal was to determine the timing and …

Greater Sage-Grouse Ecology, Chick Survival, And Population Dynamics, Parker Mountain, Utah, David K. Dahlgren

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

We estimated survival of ~ 1-day-old chicks to 42 days based on radio-marked individuals for the Parker Mountain greater sage-grouse (Centrocercus urophasianus) population. Chick survival was relatively high (low estimate of 0.41 and high estimate of 0.50) compared to other studies. Brood-mixing occurred for 21 % of radio-marked chicks, and within 43 % of radio-marked broods. Our study showed that brood-mixing may be an important ecological strategy for sage-grouse, because chicks that brood-mixed experienced higher survival. Additionally, modeling of chick survival suggested that arthropod abundance is important during the early brood-rearing period (1 - 21 days). We also …

Predation On Domestic Sheep On Summer Range Lands In Southwestern Utah, Brian Carl Palmer

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Much of the decline of the U.S. sheep industry has been attributed to losses caused by predators. Most predatory losses are inflicted on lambs rather than ewes. Losses have historically ranged from 4-8% of lamb crops, inflicting significant financial loss on ranchers. However, most research providing data on sheep predation is over 20 years old. Changes in the sheep industry as well as predation rates may make previous loss rates inapplicable to current conditions. Coyotes (Canis latrans) are the primary predator of concern when it comes to sheep losses, but increasingly, cougars (Felis concolor) and black …

Speciation, Species Concepts, And Biogeography Illustrated By A Buckwheat Complex (Eriogonum Corymbosum), Mark W. Ellis

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The focus of this research project is the complex of infraspecific taxa that make up the crisp-leaf buckwheat species Eriogonum corymbosum (Polygonaceae), which is distributed widely across southwestern North America. This complex provides an ideal taxonomic group for research into population relationships and speciation. To avoid unnecessary debates about taxonomic validity or contentious issues regarding appropriate species definitions, the historical evolution of the species concept is first reviewed in detail, demythologizing an often-assumed species problem. Following that review, the E. corymbosum complex is examined specifically.

Although eight varieties of E. corymbosum are currently recognized based on morphological characters, this group …