Biology Commons^™

Marine Heatwaves And Fish Reproduction: Endocrine Responses In The Eurythermal Sheepshead Minnow (Cyprinodon Variegatus), Isabel Villafuerte

Master's Theses

Marine heatwaves associated with climate change are increasing in frequency and severity, posing significant threats to fish populations in shallow habitats such as estuaries and salt marshes. Because temperature is a primary regulator of fish reproduction, understanding how heatwaves affect reproductive physiology is critical for anticipating the biological consequences of ongoing climate change for coastal fishes. Here we examined how simulated heatwave conditions affect the reproductive hypothalamic-pituitary-gonadal (HPG) endocrine axis in the estuarine sheepshead minnow (Cyprinodon variegatus), a eurythermal fish well suited to studying thermal stress responses in estuarine environments. Adult sheepshead minnows acclimated to a daily oscillating …

Evaluating The Commercial Aquaculture Potential Of The Native Pacific Littleneck Clam (Leukoma Staminea) As A Climate Resilient Alternative To The Non-Native Manila Littleneck Clam (Ruditapes Philippinarum)., Skylar M. Wuelfing

Master's Theses

The California shellfish industry’s near-exclusive reliance on the non-native Manila littleneck clam (Ruditapes philippinarum) creates an economic vulnerability to climate-driven disturbances, which can cause mortality events that eradicate up to 80% of stocks. This singular reliance on an introduced species highlights a need for the evaluation of native alternatives like the Pacific littleneck clam (Leukoma staminea). Our goal was to assess the feasibility of using the native Pacific littleneck in commercial aquaculture by comparing their performance to the non-native Manila littlenecks across the following conditions: 1) a five-month field outplant trial at high and low intertidal …

Hormonal, Cytokinetic, And Skeletal Response To A Single Weighted Vest Exercise Treatment: A Pilot Study To Determine Weighted Vest “Rucking” Treatment For Osteoporosis In Post-Menopausal Women, Eleanor Pell

Master's Theses

Osteoporosis is characterized by a deteriorating of bone tissue leading to brittleness and increased fracture risk that affects both men and women as they age. Postmenopausal women are of particular interest due to high risk of declining bone density, a characteristic of this population. Treatments for osteoporosis range from menopause hormone therapy, bisphosphonates, biologics, nutritional changes, and exercise. Load bearing exercise interventions have shown effectiveness for stimulating bone growth, but many factors such as lack of access, motivation, self-confidence or knowledge, prevent long term compliance. “Weighted vest rucking” refers to a variation of rucking, which is a form of exercise …

Investigating The Taxonomic Uncertainties Of Potentilla Rupincola, Natalie Elizabeth Hieber

Master's Theses

Landscape stewardship is an integral role for land managers that becomes more important when rare or endangered species occur within managed areas. Conservation across the landscape is a primary concern for land managers, but resources allocated for conservation can be limited due to many competing goals. Taxonomic uncertainty surrounding rare and endangered taxa, particularly plant taxa, that have historically been classified solely using morphological features further complicates conservation planning. One such taxon is Potentilla rupincola, a rare plant endemic to the eastern Rocky Mountains in Colorado. For over a century, botanists have debated whether P. rupincola is a distinct species …

Morphological Variation Of Lingual Glands In Wild American Alligator (Alligator Mississippiensis) Populations, Benjamin Angalet

Master's Theses

American alligators (Alligator mississippiensis) inhabit diverse aquatic ecosystems including freshwater wetlands, swamps, and estuarine rivers. As apex predators, their physiological resilience has implications for ecosystem stability and long-term conservation. With projected sea-level rise and increasing saltwater intrusion into coastal freshwater habitats, understanding the osmoregulatory capacity of alligators is increasingly important. Unlike marine-tolerant crocodilians such as the saltwater crocodile (Crocodylus porosus), which possess specialized salt-secreting lingual glands in addition to renal and cloacal mechanisms, the morphology and physiological significance of lingual glands in wild American alligators remain poorly understood. This study examined lingual gland morphology and plasma …

Life History And Distribution Of Two Species Of Cownose Ray, Rhinoptera Bonasus And Rhinoptera Brasiliensis, In Mississippi Coastal Waters, Anna Millender

Master's Theses

Historically, the American Cownose Ray (Rhinoptera bonasus) was considered the only rhinopterid residing in the northern Gulf of Mexico (GOM); however, recent studies have confirmed the presence of the Brazilian Cownose Ray (Rhinoptera brasiliensis) throughout this region. The current study investigated the life history and distribution of both species within Mississippi waters, an area that previously represented a data gap for both species. From April 2016 – July 2025, 193 R. bonasus and 94 R. brasiliensis were analyzed to describe the reproductive biology. Reproductive timing, mating, gestation length, and parturition were similar among species. Although more …

Impacts Of Halophila Stipulacea Invasion On Organic Matter Dynamics In Thalassia Testudinum Dominated Seagrass Meadows, Puerto Rico, Jonathan D. Herald

Master's Theses

Halophila stipulacea (Forsskål & Niebuhr) is a tropical seagrass native to the Red Sea, Persian Gulf, and Indian Ocean. In 2002, invasive populations of H. stipulacea were identified in the Caribbean Sea where it now forms large meadows, displaces native seagrasses, alters invertebrate and fish communities, and potentially affects organic matter dynamics in invaded meadows. This study investigated differences in organic matter dynamics between meadows of H. stipulacea and native Thalassia testudinum within the Jobos Bay National Estuarine Research Reserve (JBNERR) on the southern coast of Puerto Rico. From March 2023-March 2024, sampling was conducted across four sites to investigate …

Effects Of Urbanization On The Population Genetics And Morphology Of The White-Footed Mouse (Peromyscus Leucopus) Across An Urban–Rural Gradient, Sydney A. Morton

Master's Theses

Urbanization alters landscapes in ways that can reshape wildlife populations by changing habitat connectivity, resource availability, and selective pressures. To investigate how urbanization influences both genetic differentiation and morphology in small mammals, I examined Peromyscus leucopus (PELE) across an urban–rural gradient in northern Georgia. Using RADseq SNP data from PELE individuals across 13 sites, I quantified pairwise genetic differentiation (F_ST) and tested how various environmental variables, including impervious surface cover, human population density, and tree canopy cover, predict genetic differentiation after accounting for geographic distance. Genetic differentiation increased with geographic distance and, after controlling for isolation by …

Using Livestreaming Technology To Answer Novel Questions About The Behavior And Physiological Ecology Of The Prairie Rattlesnake (Crotalus Viridis), Max C. Roberts

Master's Theses

Recent advances in remote monitoring technology are opening up new opportunities for developing innovative natural history and biological research methodologies. In particular, the emergence of livestreaming camera technology has made recording remote video of wild and secretive animals much easier and made it possible to collect data at extremely fine temporal resolutions. In 2024, Project RattleCam launched a livestreaming camera at a Prairie Rattlesnake (Crotalus viridis) den in Colorado. The goal of this work was to study Prairie Rattlesnake behavior 24-7 throughout the species’ active season with minimal human disturbance. Additionally, I used this system to study the …

Regulation Of Spermatogenesis By The Notch Signaling Pathway, Emma O'Flaherty

Master's Theses

The Notch signaling pathway plays a significant role in gonad development and spermatogenesis, but little is known about its specific targets in the testis. The Drosophila testis contains two populations of stem cells: germline stem cells and cyst stem cells, which give rise to differentiating germline and somatic cyst cells, respectively. Notch signaling is activated in the somatic cyst cells by the Delta ligand from the germline in a region of the testes coined the “transition zone”, where somatic cyst cells progress from early cyst cells surrounding gonialblasts and 2-cell germline cysts to late cyst cells surrounding 16-cell spermatocyte cysts. …

Anthropogenic Litter In Freshwater Ecosystems: Effect On Ecosystem Processes And Spatial Distribution, Emily Johnson

Master's Theses

The rapid increase of plastic production and disposal into the environment has resulted in anthropogenic litter (i.e., trash; AL) becoming a global problem. In aquatic ecosystems, macro- and microplastics are long-lived, mobile, and interact with the physical and chemical components of aquatic ecosystems. Our objectives were to: (1) assess the impact of microplastic pollution on the ecosystem processes of ecosystem metabolism and N2 flux in an oligotrophic lake and (2) to assess the abundance and assemblage of anthropogenic litter in a large urban river. For objective (1), we added microplastics at a range of concentrations to littoral mesocosms. Ecosystem metabolism …

The Impact Of Growth Hormone-Releasing Hormone Antagonist On Human Adipose-Derived Stem Cells, Jeanne Michelle Dugas

Master's Theses

Obesity is a condition that affects over 40% of American adults and contributes to numerous preventable health issues. This condition is caused by increased adipose tissue, which forms when stem cells transform into adipocytes. Mesenchymal stem cells, including human adipose-derived stem cells (hASC), are multipotent with the ability to differentiate into adipocytes, osteocytes, or chondrocytes. Many factors affect this transformation, including the peptide growth hormone-releasing hormone (GHRH). The main role of GHRH is to trigger the release of growth hormone, but it has also been found to play an important role in adipocyte metabolism. We expect that if the differentiation …

The Antioxidant Potential Of Rosemary Leaf-Derived Nanovesicles, Shani Akila Griffin

Master's Theses

Human dermal fibroblasts are essential for maintaining skin homeostasis. However, exposure to exogenous and endogenous stressors can lead to fibroblast instability, extracellular matrix degradation, and excessive reactive oxygen species (ROS) production. These factors contribute to skin aging and ROS-induced skin disorders leading to hair loss. Adverse effects from synthetic treatments have driven interest in natural alternatives like plant extracts for skin therapy. However, the polyphenols in these treatments require an effective delivery system to ensure their stability and targeted application. Plant derived nanovesicles (PDNVs) are emerging as a promising natural alternative for therapeutic applications. Their biocompatibility, stability, and encapsulated compounds …

Pollinator Plant Communities Within Restored Montane Longleaf Pine Ecosystems, Hanen Van Rossem

Master's Theses

Historically the fire-dependent and biodiverse longleaf pine (Pinus palustris) ecosystem was the dominant ecosystem of the Southeastern US. This ecosystem’s range was massively reduced due to land conversion and fire exclusion, causing the decline of many native species. Efforts to restore and protect longleaf pine stands are now ongoing with the goal of expanding habitat and refuge for threatened species. Differences in restoration practices and prior land use may influence the extent to which restored habitat patches can support pollinators and their plants. This study compared pollinator plant biodiversity between restored neighboring montane longleaf pine stands that differed in …

Identification Of Methylation Patterns, Associated Dna Methylating Proteins, And Methyltransferase Inhibitors On The Promoter Regions Of Dax-1, Brandon Tyler Toy

Master's Theses

The DAX-1 gene (Dosage-Sensitive Sex Reversal, Adrenal Hypoplasia Congenita, Critical Region on the X chromosome, gene 1) encodes for an orphan nuclear hormone receptor and its mutation is implicated in multiple diseases including congenital adrenal hypoplasia, adrenal cancer, and breast cancer. Previous research has linked DAX-1 downregulation to tumor initiation in breast tissue, suggesting the gene acts as a tumor suppressor with respect to breast cancer. Additional studies completed by the Tzagarakis-Foster laboratory have shown that methylation of the DAX-1 promoter region is heavily influential in breast cancer development, with release of epigenetic repression resulting in slowing of cellular proliferation …

Impact Of Temperature And Microbial Infection On The Honey Bee Hemocytes, Michael E. Oeth

Master's Theses

Introduction

Honey bees (Apis mellifera) rely on hemocytes for immunity, wound healing, and hemolymph homeostasis. While 32°C reflects optimal hive conditions, suboptimal temperatures (22°C) and stressors like pathogens (Varroa destructor, bacteria) or pesticides impair hemocyte function. Using clodronate liposomes (CLD) to deplete hemocytes, we assessed how immune suppression interacts with these stressors.

Methods

Newly emerged (5-day-old) and older (15-day-old) bees were assigned to: CLD, control liposomes (LP), PBS, injection wound, or no treatment. Cohorts were exposed to 32°C (optimal) or 22°C (stressful for non-immunosuppressed bees). Fifteen-day-old bees were challenged with Escherichia coli or Staphylococcus aureus. Survival, hemolymph volume, and hemocyte …

Using Camera Stations To Investigate Occupancy Probability And Habitat Associations Of Island Spotted Skunks (Spilogale Gracilis Amphiala) On Santa Rosa And Santa Cruz Islands, Desirae Thomaier

Master's Theses

The California Channel Islands are unique in that two islands (Santa Rosa and Santa Cruz) support two endemic mesocarnivores, the island fox (Urocyon littoralis) and the island spotted skunk (Spilogale gracilis amphiala). Following the near-extinction of island foxes in the early 2000s, island spotted skunk populations increased significantly. Now that foxes have recovered, skunk captures have precipitously declined - possibly due to interspecific competition with foxes who have a similar diet but a larger body size and wider temporal niche. It has been proposed that skunks selectively use canyon bottoms and drainages with high vegetation cover and that these areas …

Plasmodium Berghei Subpellicular Microtubule Protein-1 (Pbspm-1) Is A Microtubule Stabilizing Protein That Affects Schizont Development, Manuel Joseph Widuch

Master's Theses

In eukaryotes, microtubules (MTs) are regulated by microtubule-associated proteins (MAP), only a few of which have been characterized in the malaria parasite to date. Here we present the functional characterization of STOP axonemal protein 1 (SAXO1) of the rodent parasite Plasmodium berghei. The protein exhibits high sequence and organizational conservation to the subpellicular microtubule protein 1 (SPM1) of the apicomplexan parasite Toxoplasma gondii and SAXO1 of Trypanosoma brucei. SAXO1 proteins are conserved in most eukaryotes where they form a protein family. We refer to this protein as PbSPM1. It is a 38 kD protein that is organized into an N-terminal …

Genetic Influences On Individual Variability In Western Lowland Gorilla (Gorilla Gorilla Gorilla) Social Behavior, Hadley Mueller-Hill

Master's Theses

While primates are considered highly social animals, the evolutionary origins and mechanisms underlying their social behaviors remain unclear. Not only do they exhibit an extensive range of behaviors, but individuals within the same species can also vary widely in their social interactions. Genetics play a significant role in shaping these individual variations in behavior; multiple genetic variants have been associated with differences in social behavior in mammals. Examples of these include MAOA and OXTR genes, which influence the expression of behaviors associated with antisocial and prosocial temperaments. Genetic polymorphisms affect primate interactions, impacting an individual’s ability to maintain its status …

Tricolored Bat (Perimyotis Subflavus) Population Genetic Structure In The Southeastern United States, Laura Henderson

Master's Theses

Tricolored bats (Perimyotis subflavus) have experienced substantial population losses from white-nose syndrome (WNS), a disease caused by the pathogenic fungus Pseudogymnoascus destructans (Pd) which infects hibernating bats. Determining population genetic structure helps assess genetic diversity and the impacts of wildlife threats to populations. Pre-WNS data shows weak-to-negligible structure and panmictic P. subflavus populations at core portions of their range. However, current genetic data from their southeastern U.S. range is lacking. I sought to determine whether recent genetic data help resolve genetic structure among southeastern populations and assess genetic differences at two stages of impact: post-WNS and …

Geomorphic Assessment And Flow Modeling Of Pearl Darter (Percina Aurora) Habitat In The Pascagoula River Watershed, Malia Davidson

Master's Theses

Freshwater ecosystems are complex ecosystems driven by hydrologic, geomorphic, and biological processes. Considering both abiotic and biotic factors is important to understanding resident species habitat. Geomorphology is a known, but often neglected factor in habitat assessment for freshwater fishes. A crucial feature commonly seen in alluvial stream systems are sandbars, which are dynamic and variable sediment structures that are known to have many associated species. One such species is the Pearl Darter, Percina aurora, a federally threatened species that only resides in the Pascagoula River watershed. Despite its status, habitat preference remains unclear. To fill this knowledge gap, I …

Drivers Of Microparticles Abundance In Freshwater Fish And Macroinvertibrates, Elizabeth Kazmierczak

Master's Theses

Anthropogenic microparticles (MP) (i.e., particles < 5 mm) are defined as materials of manufactured origin found in the environment. They are widespread and a rapidly emerging global contaminant. MP include microplastics (< 5 mm), as well as other microfibers or particles, which can be synthetic, semi-synthetic and non-synthetic. Rivers are a critical source of plastics to oceans, and MP within rivers are retained in part though biological processes, including ingestion. MP ingestion by freshwater biota varies by proximity to point sources (e.g., wastewater treatment plants; WWTP), overall environmental concentrations, and trophic level and functional feeding groups, but few studies have examined these factors together. In our first study we examined fish collected in the North Shore Channel of the Chicago River to determine MP abundance within organisms. We then compared trophic position (i.e., δ15N) and proximity to a WWTP. With all species combined, MP concentration were not significantly different across study sites, but stable isotopes increased downstream. Considered individually, MP abundance relative to WWTP proximity varied by species, which we attributed to habitat preference and mobility. In a second project, we collected macroinvertebrates from three different watersheds in North America and compared the abundance of MP in macroinvertebrates to concentration within the environment (i.e., water column, surface, and benthic). Functional feeding groups were a significant predictor in the amount of microparticles found in macroinvertebrates. Additionally, the concentration of water column microparticles showed a positive relationship with all macroinvertebrate’s microparticle abundance. Results will aid in understanding the ecological impacts of MPs on aquatic food webs and the pathways in which they can enter.

The Skin Microbiome And Cutaneous T-Cell Lymphoma, Gail Hillary Lantaca Enriquez

Master's Theses

Skin microbiota is associated with disease activity in cutaneous T-cell lymphoma (CTCL). A common treatment for CTCL, narrowband ultraviolet B (nbUVB) phototherapy, has shown to shape the skin microbiome in association with disease improvement in other skin disorders such as atopic dermatitis. To assess the effect of nbUVB phototherapy on the skin microbiome, we performed a longitudinal analysis of skin samples of CTCL patients receiving nbUVB. We found that the treatment led to increased bacterial diversity and reduced abundances of Staphylococcus aureus and Staphylococcus lugdunensis, both bacteria known to be pathogenic. These findings imply that nbUVB treatment changes the skin …

Impacts Of Stormwater And Land Cover On The Abundance, Transport, And Composition Of Anthropogenic Litter In Urban Watersheds, Bailey Austin Schwenk

Master's Theses

Anthropogenic litter (AL; trash) is defined as any manufactured item that ends up in the environment. AL consists of many different materials including glass, metal, and plastic, the latter of which typically represents a dominant constituent and has been a major focus of research. Plastic litter and other AL types are pervasive to all types of ecosystems, are persistent in the environment, and are increasing. Rivers are a major conduit transporting AL to oceans. However, rivers also retain and transform AL. More research is needed to understand AL dynamics within rivers, which will improve global models of AL movement and …

Pattern, Process And The Evolution Of Sexual Dimorphism In Three-Spine Stickleback Fish Gasterosteus Aculeatus From Vancouver Island, British Columbia, Katie Van Dame

Master's Theses

Males and females of a species often differ from one another in phenotype—a phenomenon known as sexual dimorphism. Sexual dimorphism is most often attributed to sexual selection. However, sexual dimorphism also derives from natural selection when resource competition generates disruptive selection favoring specialization on different resources, resulting in niche partitioning and the evolution of dimorphism in traits related to competition. Sexual dimorphism may be an important route to increased individual fitness (i.e., more resources, more survival). For example, ecologically driven divergent selection between sexes may derive from differences in their environments, resulting in the evolution of dimorphism in traits related …

Terrestrial Salinization Impacts On Growth And Behavior Of A Common Detritivore Armadillidium Vulgare (Isopoda), Danielle Harmoney Orcutt

Master's Theses

Climate change and human activities are changing the nutritional landscape by increasing the availability of some essential elements and decreasing others. Sodium (Na) is an essential element in heterotrophs, which is required for water regulation, nerve function, and muscle function. Heterotrophs can acquire Na through diet and environment, often experiencing limited availability of Na due to plants concentrating Na 10-100 times less than heterotrophs need. The Sodium Subsidy-Stress (SSS) hypothesis posits that organismal performance follows a hump-shaped curve of a physiological response, where Na acts as a subsidy, increasing organismal performance such as growth until an optimal threshold is reached, …

Division I Collegiate Baseball Pitching Performance In Relation To Forearm Kinematics And Kinetics, Christopher W. Watson

Master's Theses

This thesis investigates physical and anthropometric factors influenced by forearm rotation biases associated with supination and pronation on pitch characteristics among Division I college baseball pitchers. The study involved twenty-two participants who underwent comprehensive physical assessments, including measures of forearm strength, range of motion, and grip strength, as well as finger and hand length measurements. Ball flight metrics were collected during intrasquad scrimmages using advanced radar tracking technology. Results revealed significant relationships between distinct physical biases of strength in pronation and supination, pinch strength, anthropometrics such as middle finger length, and specific pitch characteristics. This study lays the groundwork for …

Evolutionary Patterns Of Anolis Lizard Skulls: An Investigation In Geometric Morphometrics And An Educational Exploration Of Structure And Function, Katherine Beyer Starr

Master's Theses

This study explores the evolutionary patterns of Anolis lizard skulls and integrates findings into a curriculum focused on elucidating the structure and function of a lizard's head. The first objective was to develop an understanding of how the evolutionary patterns, of an extraordinary group of lizards (Anolis) compares to their relatives. Most of the prior research on Anolis morphology has focused on the post-cranium because of its significance towards subdivision of the arboreal habitat. But the group’s remarkable diversity in head shape has been seriously under-investigated. By performing geometric morphometric analysis of skull shape across a large sample of anoles …

Observations Of Currents, Waves, And Turbulence Within A Giant Kelp Forest In Stillwater Cove, Carmel, California, Logan A. Grady

Master's Theses

Nutrient distribution and propagule dispersal within Giant kelp (Macrocystis pyrifera) forests are significantly influenced by turbulence. In-situ measurements of turbulence within giant kelp forests are limited and driving mechanisms are primarily informed by controlled-flume experiments. This study investigates relationships between currents, surface gravity waves, and turbulence within a kelp forest through deployment of moored instrumentation and kelp surveys in Stillwater Cove, California during summer of 2022. Oceanographic conditions were primarily driven by coastal upwelling and a semi-diurnal internal tide, which was associated with cooling events and enhanced onshore velocity within the kelp forest during rising tides. Estimates of gradient Richardson …

Seasonal Dynamics Of The Introduced Sponge Hymeniacidon Perlevis In The Elkhorn Slough, California, Usa, Jackson Hoeke

Master's Theses

Hymeniacidon perlevis is a cosmopolitan sponge with a seasonal life cycle We investigated seasonal and interannual dynamics of H. perlevis in Elkhorn Slough estuary, where it is an introduced species, and explored correlations between sponge cover and environmental conditions. We used sponge cover to estimate the potential effects H. perlevis on its environment and how those could vary across its seasonal life cycle. We found that successful recruitment is currently restricted to the upper estuary and while it varies annually, the frequency and density of sponge recruits have generally increased from 2007 to 2023. A seasonal life cycle was confirmed …