Biology Commons^™

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 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 …

The Effects Of Low-Dose Ionizing Radiation On Voles From The Chernobyl Exclusion Zone, Justin Sindoni

Senior Theses

Much is known about the effects of high doses of ionizing radiation exposure, but little is known about the effects of low doses of ionizing radiation over extended periods of time. Nuclear power plant disasters, in particular the 1986 Chernobyl disaster, have led to long-term radioactive contamination of their surrounding areas, and more research is needed to learn about the effects of the contamination. In order to better understand the impacts of low-dose ionizing radiation on animal populations, bank voles (Myodes glareolus) from the Chernobyl exclusion zone were studied. Voles were captured from 64 sites throughout the exclusion zone, and …

Factors Influencing Induction Of Desiccation Tolerance In Bryophytes: Redefining Fundamental Aspects Of The Organism’S Relationship With The Environment In Xeric Habitats, Joshua Lee Greenwood

UNLV Theses, Dissertations, Professional Papers, and Capstones

If one wishes to understand the ecological role, range, habitat preferences, selective pressures, reproduction, response to climate change, and the potential for survival under climactic change, range expansion and range contraction for species and populations of bryophytes, an understanding of their survival of the desiccated state, is essential. In order to further our understanding of desiccation tolerance in mosses, three projects were undertaken. The first of these investigated the nature of desiccation tolerance in mosses, specifically if desiccation tolerance can be induced; thereby providing a desiccation tolerant phenotype in a moss species generally considered desiccation sensitive (Physcomitrella patens, the model …

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 …

Gene Expression Profiling In The Larval Fat Body Of Desiccation Selected Drosophila Melanogaster, Adriana Michelle Charles

UNLV Theses, Dissertations, Professional Papers, and Capstones

Drosophila melanogaster selected for resistance to desiccation (no food or water) display slower development and a higher body mass compared to fed controls due to an extended third larval instar. I hypothesize that desiccation selected D. melanogaster larvae will have a different gene expression profile compared to fed controls. Separate populations of D. melanogaster were subjected to desiccation (no food or water), starvation (no food) until 80-85% mortality, for 75 generations. mRNA from the larval fat body was collected at 88 hours, 96 hours, 112 hours and 120 hours post-hatching. Four replicate samples were used for each condition and time …

The Aerodynamic Effects On Flight Patterns And The Evolutionary Changes In Pterosaurs, Johnathan D. Talik

Maseeh Summer Undergraduate Research Experience

Early pterosaurs were the first vertebrates to achieve powered flight, and remained small-to-medium sized from the Triassic Period to the end of the Jurassic Period. During that interval, lasting from 210 million years ago to 66 million years ago, pterosaurs underwent a notable changes at the end of the Jurassic Period and through the Cretaceous Period. They were abruptly replaced by much larger forms, characterized by great size and peculiar head ornamentation, among other unique and notable morphological features. While many different explanations theorize why and how the features of the pterosaurs changed over the Cretaceous Period, the aerodynamic influences …

Timing And Consequences Of Pleistocene Megafaunal Population Collapse In South America, Marco Felipe Raczka

Theses and Dissertations

A key question for ecologists and paleontologists studying the extinction of the Pleistocene megafauna is: what caused the extinction of these animals? Was the extinction of megafauna caused solely by human-hunting pressure, or was it a consequence of climate change? Could these extinctions be caused by a combination of both factors? Was this wave of extinction temporally uniform across South America? Despite the recent surge of research on this subject, these questions remain largely unanswered. Spores of Sporormiella, a genus of obligate coprophilous fungi, are now widely used to detect mega-herbivore presence and even estimate their abundance in paleoecological reconstructions. …

The Vocal Babbling Behavior And Its Sibling Effects In A Wild Parrot, Tatiana Dolgushina

Theses and Dissertations

Vocal learning is a rare trait in the animal kingdom, defined as the sensorimotor imitation of sounds, and is only found in select groups of birds and mammals. Parrots are a behaviorally complex group of birds, famous for their ability to mimic social companions, but how they develop this ability in the wild has received little attention. The vocal learning period consists of a complex vocal babbling stage, a crucial developmental precursor for imitation of adult vocalizations in humans and songbirds, but has not been described in any of the 360+ parrot species. This project quantifies potential individual variation in …

Multifunctionality Of Cover Crops On Organic Vegetable Farms In South Texas, Savannah M. Rugg

Theses and Dissertations

Situated in deep South Texas, the Lower Rio Grande Valley (LRGV) is considered one the most productive agricultural regions in the southern US. With the highest concentration of organic farms in the state (Hidalgo county), finding management practices that comply with organic certification is increasingly pertinent. Cover cropping can serve multiple functions in an agroecosystem such as: suppressing weeds, increasing soil organic matter (SOM), increasing soil nitrates, and enhancing soil biodiversity. The four cover crops (lablab, sunn hemp, sudangrass, and pearl millet) were assessed to see their potential to increase soil nitrogen, to increase soil organic matter, and to suppress …

Social Dynamics, Network Structure, And Information Diffusion In Fish Shoals., Matthew Jerome Hasenjager

Electronic Theses and Dissertations

Animal populations are often highly structured, with individuals differing in terms of whom they interact with and how frequently they do so. The resulting pattern of relationships constitutes a population’s social network. In this dissertation, I examine how environmental variation can shape social networks and influence information flow within them. In Chapter I, I review the history of social network analysis in animal behavior research, and discuss recent insights generated by network approaches in behavioral ecology. I focus on the fields of: social learning, collective behavior, animal personalities, and cooperation. Animal network studies are often criticized for a lack of …

Function Of The Enterobactin Operon Of A. Actinomycetemcomitans In The Presence Of Catecholmines And Iron., Taylor Johnson

Electronic Theses and Dissertations

Background: Aggregatibacter actinomycetemcomitans (Aa) possesses a two-component system, QseBC, which is key in biofilm formation/virulence and is activated in the presence of iron-catecholamine complexes. Aa does not synthesize enterobactin, a catechol-based siderophore, yet possesses the machinery for recognition and uptake. We hypothesize that Aa is able to acquire iron by catecholamine mediation through the enterobactin receptor/transporter. Methods: By insertional mutation, we attempted to delete the enterobactin permease from the genome using suicide vector pJT1. A growth curve of truncated mutant ΔfepA was also conducted to observe growth in the presence of iron and catecholamines. Statistical significance was determined by ANOVA …

Molecular Analysis Of Β-Lactamase Genes In Antibiotic Resistant Bacteria, Neisha Medina Candelaria

Honors Projects

The wide overuse of antibiotics in both the medicine as well as agricultural has lead to a problem with antibiotic resistance. This present research experiment aims to identify various environmental bacterial samples to find antibiotic resistant strains. By looking at these strains we are then able to develop a system to monitor how antibiotic resistance spreads and develops over time. We can then compare different bacteria species to identify any similarities and the prevalence of the resistant strains.

Transcriptome Profiling And Long Non-Coding Rna Identification In Grapevine, Zachary Noel Harris

Graduate Theses/Dissertations

Next-generation sequencing technologies have provided access to vast quantities of nucleic acid sequence data. The resulting wealth of information enables biologists to address complex biological questions in species for which a high-quality well-annotated reference genome sequence has yet to be generated. The cultivated grapevine, Vitis vinifera, has a relatively poorly annotated reference genome. In addition, it is a highly heterozygous species which further hinders the annotation of its genome and the characterization of its transcriptome. Here, I annotated Version 2 of the 12X V. vinifera genome using RNA-seq data derived from the variety ‘Riesling' by employing the most up-to-date computational …

Establishing A Method Of Microrna Profiling In Addition To Comprehensive Chromosome Screening In The Same Trophectoderm Biopsy, Jessica Rajchel

Theses, Dissertations and Culminating Projects

Early embryo development in humans is a complex process. Due to recent advances in research, many improvements have been made in in vitro-fertilization (IVF) outcomes. Success has been credited to the application of comprehensive chromosome screening (CCS) however, not every euploid embryo will always implant due to various outside factors (1). More reproductive markers would need to be evaluated to optimize the success of implantation of euploid embryos.

MiRNAs are emerging as important regulators of cellular differentiation and may be involved in the human pre-implantation process. Any dysregulation of microRNA expression may play an important role in the progression or …

Green Tea Polyphenols As Potential Anti-Endospore Agents In Targeting Bacillus Spp., Giselle Lalata

Theses, Dissertations and Culminating Projects

Endospores are dormant structures of endospore-forming bacteria, such as Bacilli and Clostridia, which enable them to become resistant to any harsh environmental conditions such as heat, chemicals, and UV radiation, thus surviving for many years. When the environment is favored for growth, the spores undergo the germination process which enables them to become vegetative cells again. This becomes a threat to the food and medical industry as they can cause food spoilage, food poisoning, and contamination.

Green tea, made from the plant, Camellia sinensis, has become the second most consumed beverage in the world due to its medicinal benefits. It …

Plant-Microbial Interactions Are Strong Determinants Of Plant Population And Community Dynamics, Yan-Yi Anny Chung 9485698

Biology ETDs

Plant-microbial interactions are ubiquitous and yet the consequences of these interactions on plant population and community dynamics are relatively unknown. Here, we used two different classes of plant-microbial interactions to examine their effects on key plant population and community characteristics such as commonness and rarity, competition and coexistence, as well as community stability.

Vertically-transmitted endophytes had stage-dependent effects on the population growth of two grass species Poa sylvestris and Poa alsodes, and generally increased host population growth rates. However, it was the intrinsic demographic advantage of P. sylvestris that allowed its population to grow at a much faster rate …

Clinically Relevant Model Of Temporomandibular Disorder, Neelima Chelliboina

Graduate Theses/Dissertations

Temporomandibular joint disorders (TMD) is a debilitating orofacial pain condition that affects a significant portion of the population and is associated with a decrease in quality of life. Results from the Orofacial Pain Prospective Evaluation and Risk Assessment Study (OPPERA) study provide evidence that risk factors such as neck muscle tension, prolonged jaw opening, and female gender increase the likelihood of developing TMD. Routine visits to an orthodontist or dentist can result in injury to the jaw joint or muscles of mastication. I tested the hypothesis that neck muscle inflammation and female gender increase the risk of developing chronic pain …

Quantitative Behavioral Analyses Of Ozark Hellbender Reproduction And Paternal Care, Rachel Ann Settle

Graduate Theses/Dissertations

The Ozark hellbender (Cryptobranchus alleganiensis bishopi) is a federally endangered aquatic salamander. While some anecdotal observations have been reported, no quantitative assessments of reproductive behaviors have been made. I quantified video-recordings of two breeding events at the Saint Louis Zoo. Hellbenders were housed in an indoor stream outfitted with 4 cameras. General activity and agonistic behaviors increased through the first oviposition, peaked during inter-oviposition, and declined abruptly following the second oviposition. Following oviposition, males guard their eggs until hatching. I also quantified behavior of a guarding male from video footage collected by MDC from a nest in the North Fork …

Spatial Learning Of Shelter Locations And Associative Learning Of A Foraging Task In The Cottonmouth, (Agkistrodon Piscivorus), Rhyan Robert Friesen

Graduate Theses/Dissertations

Learning processes can have significant adaptive value in mediating behaviors with important fitness consequences. For snakes, learning may ensure the localization of key resources including food and shelter. Snakes are proportionately underrepresented in reptile learning studies, and the majority of research subjects are within the family Colubridae. I presented captive cottonmouth snakes with two types of learning challenges. In a spatial learning experiment, snakes learned the location of a cover object in a circular laboratory arena, as demonstrated by a 56% reduction of time and 57% reduction of distance travelled to a shelter across a series of training trials. In …

The Effects Of Carbon Nanotubes And Silver Quantum Dots On Gas Exchange In Arabidopsis Thaliana, Maryam Ibrahim Subaylaa

Graduate Theses/Dissertations

Engineered nanoparticles (ENPs) are increasingly being used in commercial products, and may accumulate in soils when the products are disposed. I examined the effects of two common ENPs, carbon nanotubes (CNTs) and silver quantum dots (Ag-QDs), on plant gas exchange. To do this, I grew Arabidopsis thaliana in soil (n=36) for 6 weeks and added a CNT suspension at increasing concentrations (10, 30, 90, 150, 190, 250 μg/ ml) each week. I also grew A. thaliana in petri dishes (n=83) containing Murashige and Skoog (MS) medium, with a concentration of 4μg/ ml Ag-QDs or 4μg/ml CNTs. I measured carbon assimilation …

Thermal Response Of Behavior And Gene Expression Of Heat Shock Proteins In The Lined Seahorse, Hippocampus Erectus, Cara Johnson

Theses and Dissertations

The lined seahorse, Hippocampus erectus, is a dispersal-limited fish residing in the coastal and estuarine habitats of the Western Atlantic. With sea surface temperatures expected to rise +2°C in the next 85 years, these dispersal limited fish will experience varying degrees of short-term (acute) and long-term (chronic) heat stress events. Previous studies have indicated that these different durations of increased temperatures will elicit distinctive behavioral changes in seahorses, but the molecular mechanisms underlying these changes are yet unknown. Three-hundred captive-bred Hippocampus erectus were exposed to control, mild, severe, and lethal temperatures for different durations to assess how these animals respond …

The Impact Of Marine Protected Areas On Reef-Wide Population Structure And Fishing-Induced Phenotypes In Coral-Reef Fishes, Robert Young Fidler Iii

Theses and Dissertations

Overfishing and destructive fishing practices threaten the sustainability of fisheries worldwide. In addition to reducing population sizes, anthropogenic fishing effort is highly size-selective, preferentially removing the largest individuals from harvested stocks. Intensive, size-selective mortality induces widespread phenotypic shifts toward the predominance of smaller and earlier-maturing individuals. Fish that reach sexual maturity at smaller size and younger age produce fewer, smaller, and less viable larvae, severely reducing the reproductive capacity of exploited populations. These directional phenotypic alterations, collectively known as “fisheries-induced evolution” (FIE) are among the primary causes of the loss of harvestable fish biomass. Marine protected areas (MPAs) are one …

Circadian Rhythms In The Retina Of The Atlantic Tarpon, Megalops Atlanticus, Kristin Leigh Kopperud

Theses and Dissertations

Light is a critically important environmental variable in the lives of marine organisms, affecting physiology and behavior acutely and dictating daily biological rhythms and seasonal reproduction in the long-term. In unpolluted natural environments, the daily light-dark cycle is a reliable environmental cue, but with today’s rapid coastal development, light pollution is an increasingly serious threat to living things, including marine fish. Alterations to the natural light-dark cycle may have profound implications for the health and longevity of organisms by interfering with the function of their internal timekeeping mechanisms. While extensive research exists on the harmful effects of inappropriate light on …

Reef-Building Threatened By Ecosystem Decline: A Case Study From Buck Island, U.S. Virgin Islands, Elizabeth M. Whitcher

Theses and Dissertations

Coral reefs are critical barriers to coastal erosion and flooding throughout tropical regions, but their role in coastal protection is threatened by declining coral populations and sea-level rise. Climate change is causing widespread losses of live-coral cover on Caribbean reefs, and is reducing the capacity of reef-building to keep pace with sea-level rise. Reefs that lag behind rising sea level will struggle to maintain their role as protective barriers, as rising water-levels over shallow reef-crests result in a reduction of the dissipation of wave energy. A clear understanding of reef-building processes in the Caribbean will be a critical component in …

Late Holocene Climate And Vegetation Change In Central Michigan, Rachel Kathleen Sales

Theses and Dissertations

Understanding the effects of drought and temperature change on eastern North America will be key in the context of future climate change. Perhaps the best method to understand how drought and temperature will impact this area is to study its paleoecological record. The records presented here, from Houghton Bog (44°23'4.50"N; 84°44'18.90"W) and Higgins Bog (44°28'58.90"N; 84°47'41.40"W) provide an opportunity to study the effects of drought and temperature on the interior of the Lower Peninsula of Michigan (hereafter central Michigan) during the Late Holocene (c. 4200 cal BP to present day). Pollen, charcoal, and testate amoebae records were analyzed to infer …

Effects Of Marsh Fragmentation And Patch Area On Fish And Nekton Assemblages In Mississippi, Jennifer R. Main

Honors Theses

Fragmentation divides continuous habitat into smaller patches. Fragmentation can also produce smaller populations of species, because fragmentation can split a population into smaller groups. Both terrestrial and aquatic ecosystems suffer from fragmentation. There are a variety of fishes that live along marsh, each depending upon the marsh for protection, food, and sometimes even competition. Species richness of fishes can be altered due to marsh fragmentation. I predict islands with a larger patch index should have a higher species richness of fishes. For this study, fish assemblages at 20 islands of marsh were sampled in the months of June and July …

On The Identity Of The Adventive Species Of Eufriesea Cockerell In The Usa: Systematics And Potential Distribution Of The Coerulescens Species Group (Hymenoptera, Apidae), Victor H. Gonzalez, Terry Griswold, Marianna Simões

All PIRU Publications

In the summer of 2010, two male specimens of the neotropical orchid bee genus Eufriesea Cockerell were collected in the Guadalupe Mountains of western Texas and southeastern New Mexico, USA. We tentatively identified them as E. coerulescens (Lepeletier de Saint Fargeau) because of the uncertainty surrounding the limits of this taxon and hypothesized that they were members of a persistent bee population, rather than long-distance transient vagrants. The goals of this paper are to clarify the identity of these specimens, assess the species limits of E. coerulescens, and to evaluate suitability of habitats in the USA for this adventive …

Isolation Of A Mycobacterium Virus With The Infectivity Rate Tested At Various Temperatures, Katie Wegenast

Undergraduate Theses

Isolation techniques developed by the HHMI and the SEA-PHAGES program were used to obtain a bacteriophage from a mixture of loamy clay soil. The sample was retrieved from a forest edge in central Kentucky. The isolate produced large lytic plaques on a lawn of the bacterium Mycobacterium smegmatis. The bacteriophage was purified, amplified, and analyzed using restriction digest analysis with visualization by gel electrophoresis. Restriction digest analysis suggests the virus belongs to a group known as “A”. Mycobacteriophages are placed into distinct groups based on DNA sequences comparison. The next step in the procedure will be to document with …

Spatial Ecology Of The Adult And Neonate Eastern Box Turtle In A Forested Landscape, Patrick B. Laarman

Masters Theses

A thorough understanding of spatial ecology is fundamental when developing and implementing conservation strategies for imperiled turtle species. I investigated spatial ecology of adult and neonate eastern box turtles in the Manistee National Forest (MNF), Michigan. My primary objectives were to evaluate relative habitat preferences of adults and document residency time of neonates in natal openings. I radio-fitted 25 adults, protected 64 nests, and radio-fitted 66 neonates. Mean home range size for adults (n = 25 turtles) was 16.4 ha ± 2.4 SE (100% Minimum Convex Polygon). I detected non-random habitat use by adults (Wilks Ʌ = 0.202, df = …