Biology Commons^™

Liver X Receptor Α (Lxrα) Regulates 5Β-Reductase (Akr1d1) Expression In Avian Embryos: Implications For Yolk Steroid Metabolism, Ryan T. Paitz, Sara E. Waters, Delaney K. Reynolds, Emily M. Drew, Emily P. Harders

Faculty Publications – Biological Sciences

Steroid-mediated maternal effects are well-studied as a source of phenotypic variation. In bird eggs, the yolk contains various steroids that can influence embryonic development. However, one complicating factor in understanding how yolk steroids affect development is that the embryo metabolizes yolk steroids to regulate exposure. The 5β-reduction of steroids by the enzyme 5β-reductase (AKR1D1) has been identified as a pathway through which yolk progesterone, testosterone, and corticosterone are all metabolized early in avian development. We set out to characterize the mechanism through which AKR1D1 expression is regulated in chickens (Gallus gallus) during embryonic development. We found …

Geographic Variation In Proteomic Responses To Ocean Acidification In A Cold-Water Coral (Balanophyllia Elegans), Keana A. Richmond

Cal Poly Humboldt theses and projects

In the face of a rapidly changing climate, assessing organismal responses to future stressors in the context of current, natural exposure to stress could provide key insights to understanding marine ecosystem resilience. I used Balanophyllia elegans, a cold-water, solitary, azooxanthellate coral as a model to better understand how varying oceanographic conditions across its geographic range have shaped its ability to tolerate and potentially adapt to current and future ocean acidification conditions. I collected B. elegans individuals from four sites across 2,500km of their range and subjected them to two pH treatments to investigate site-specific protein expression in response to …

Species Boundaries Of The Rare Menzies’ Wallflower (Brassicaceae: Erysimum Menziesii), An Endemic Of The Northern California Coast, Cameron M. Jones

Cal Poly Humboldt theses and projects

Morphological similarity among geographically isolated populations can obscure deep evolutionary divergence, especially when convergent evolution under similar environmental conditions yields comparable phenotypes across independent lineages. Such cryptic diversity is likely underestimated in hotspots like the California Floristic Province (CFP), a global biodiversity hotspot, defined by its Mediterranean-like climate and encompassing most of California, southwestern Oregon, and northwest Baja California. The CFP is home to a disproportionate number of narrow endemics whose origins and evolutionary relationships remain poorly understood. Here, I investigate the evolutionary origins of Erysimum menziesii (Brassicaceae), a federally endangered California coastal dune endemic whose fragmented distribution has led …

The North American Diatom Symposium: A Brief History, 1970-2024, Mark B. Dlund, Julie Wolin, Adam J. Heathcote

Biological, Geological, and Environmental Faculty Publications

The 2024 North American Diatom Symposium (NADS) represents the twenty-seventh time that the group formally gathered and the fourth time the group convened at Iowa Lakeside Lab. The first NADS meeting, called "Ecology of Freshwater Diatoms," was held in October 1970 at the Cedar Creek Natural History Area in Minnesota and was organized by J. Platt Bradbury and Ryan Drum. Four years later, the group gathered at Hocking Hills in Ohio for the "Second North American Symposium on Diatom Systematics and Ecology", a meeting that set the stage for the now biennial gathering of this informal society. Over the last …

Exploring The Synergistic Effects Of Cisplatin And Curcumin In Osteosarcoma Cells, Ellis Stafford, Alexa Cabral, Andrea Florian Ph.D., Reese Nagy

SPARK Symposium Presentations

Osteosarcoma (OS) is a highly aggressive bone cancer characterized by rapid metastasis, which drastically reduces patient survival rates from 70% in localized cases to 30% upon metastasis. Current treatments combining chemotherapy with cisplatin and surgical intervention are often ineffective against metastatic OS and are associated with significant side effects. Cisplatin targets cancer cells by binding to DNA, disrupting transcription and replication, and inducing apoptosis. To address the challenges associated with current treatments, this study investigates the potential of combining cisplatin with curcumin, the bioactive compound derived from turmeric, as a novel therapeutic approach. Curcumin has shown anticancer properties by inducing …

A Sensory Ecology Of Fear: Moonlight-Mediated Predation Risk And Foraging Behavior In Neotropical Electric Fish, Chiu Lok Poon

Graduate Studies Theses and Dissertations 2026

Animals must forage to acquire energy for survival and reproduction, yet foraging exposes them to predators. This creates a trade-off between energy intake and safety, wherein the perception of predation risk alone can alter activity patterns. Within this trade-off, risk, energetic needs, and sensory adaptations vary, shifting the balance and favoring different foraging strategies. Using Neotropical electric fish as a study system, I investigated how foraging under predation risk is shaped across biological scales, including environmental dynamics, interspecific sensory differences, activity-timing mechanisms, and intraspecific variations. These nocturnal fish emit continuous electric signals to sense their environment, allowing non-invasive monitoring of …

Population Genomics And Evolution Of Pseudomonas Aeruginosa, Samara T. Choudhury

Electronic Theses & Dissertations (2024 - present)

Pseudomonas aeruginosa is a Gram-negative bacterium ubiquitous in diverse environments and an opportunistic pathogen in humans. It is a leading cause of chronic lung infections in cystic fibrosis patients and of hospital-acquired pneumonia and sepsis. With a large flexible genome and abundant mobile genetic elements, P. aeruginosa exhibits high levels of antimicrobial resistance (AMR), making it a significant public health threat. Evolutionary processes such as homologous recombination, and horizontal gene transfer generate extensive genomic diversity in this species and facilitate the spread of resistance genes. In this dissertation, I investigate the genetic and evolutionary factors shaping P. aeruginosa population structure …

The Effect Of Sex On The Signal Transmission Of Duetting Bay Wrens, Rachel C. Schinzler

Theses and Dissertations

During communication, senders send signals for their benefit to elicit a behavioral response from a receiver. Acoustic signals are efficient for long-distance signaling; however, they are influenced by environmental features, such as foliage density, humidity, temperature, and time of day. Individuals can overcome these challenges by using signals with a trajectory of peak frequency, frequencies, volumes, and timing best suited to signal transmission in their environment. Signal transmission has been studied at the species level; however, not much is known about sex differences within the same species. Duetting species provide a useful system for examining sex-specific challenges in transmission, as …

Feral Horses And Native Ungulates: Evaluating The Potential For Competition In Predator–Prey Communities Of Alberta’S Upper Foothills, Birch Gano

Graduate Student Theses, Dissertations, & Professional Papers

Feral herbivores are expanding in range and numbers globally, yet their community-level effects in ecosystems are poorly resolved. We evaluated whether feral horses reshape predator–prey–vegetation dynamics in Alberta’s Upper Foothills, Canada, through two pathways; i) potential exploitative competition for forage and ii) apparent competition via shared predators. We combined fecal DNA metabarcoding with remote wildlife cameras to quantify diets, spatiotemporal co-occurrence, and the role of horses in carnivore diet. We analyzed 241 ungulate scats (feral horses, elk, bighorn sheep, cattle, moose, and deer), 96 combined camera-years at 23 sites, and 190 carnivore scats (wolves, cougars, coyotes, bears) from 2023–2025. The …

Evaluating Multi-Year Transferability Of Single- And Multi-Class Machine Learning For Remote Monitoring Of Beaver-Engineered Landscapes, Harris J. Sloan

Graduate Student Theses, Dissertations, & Professional Papers

Long-term satellite image archives enable ecological monitoring at large scales, but manual extraction of fine-grained features (e.g., beaver dams) remains time-consuming. Machine learning models may automate these tasks, but their temporal transferability for multiannual monitoring is still poorly resolved.

We evaluated the performance of two complementary neural-network frameworks across a 100,000-hectare watershed in Montana USA, using a decade of satellite imagery (2014-2024): (i) a single-class ResNet-50 beaver dam detector, and (ii) a multi-class ResU-Net landcover classifier.

In 2024, the dam detector identified 352 of 404 mapped dams, achieving balanced accuracy = 93.6%, precision = 79.8%, recall = 87.1%, F1 = …

Differentiation Of Cell Populations In Saliva-Skin Mixtures Using Autofluorescence Profiling, Kara Fairfax

Master of Science in Forensic Science Directed Research Projects

While DNA profiling of sexual assault evidence can identify biological contributors, determining the tissue source of recovered profiles remains a significant challenge, particularly in cases of suspected oral assault involving mixtures of epithelial cells. The initial goal of this study was to identify non-genetic signatures for differentiating two types of epithelial cells relevant to oral assaults, saliva epithelial cells and epidermal skin cells. To develop tissue-specific signatures, reference cell populations from saliva and epidermal skin surfaces were collected from 20 donors and analyzed using full spectrum flow cytometry.

Results from single-source reference samples showed that saliva-derived particle populations exhibited higher …

Friends In Niche Places: An Examination Of Anole Abundance And Habitat Use In An Urban Environment Using Point Transect Distance Sampling, Ethan Gau

Honors Undergraduate Theses

Lizards in the genus anolis occupy a wide range of ecological niches, often sharing the same environment due to niche partitioning. In central Florida, the main species of anoles found are the native A. carolinensis and the invasive A. sagrei, two generalist anole species that partition into trunk-crown and trunk-ground niches in each other’s presences respectively. I surveyed the UCF main campus using Apollo Circle as the border for my study area, and I used point sampling to estimate the population abundance and density, while also collecting data on perch substrate, height, and canopy coverage. Population estimates for A. …

Data And Code From: Migration Speed, Timing, And Long-Term Shifts In Age Structure In North American Passerines During Fall Migration, Dylan M. Osterhaus, Martha J. Desmond, Timothy F. Wright

Biology: Datasets

No abstract provided.

A Field Test Of The Role Of Biofluorescence In Territorial Salamanders, Kasey Watterson, Cari-Ann M. Hickerson, Carl Anthony

2026 Faculty Bibliography

Biofluorescence is recognized as an important form of visual communication, yet its function remains largely untested in many terrestrial species. In Eastern Red-Backed Salamanders (Plethodon cinereus), fluorescence of the postcloacal gland is a sexually dimorphic trait most strongly expressed in males. Because fluorescence can be displayed during territorial contests, we hypothesized that fluorescence in male P. cinereus would be positively related to resource holding potential (RHP) of territorial residents in the field. To test this hypothesis, we examined the relationship between fluorescence and two separate variables: body condition (as a proxy for RHP) and territory quality (the expected payoff from …

An Exploratory Analysis Of The Role Of Sex In Load Carriage, Rachel E. Perez, Dustin R. Slivka, Brent C. Ruby

Graduate Student Theses, Dissertations, & Professional Papers

Axially loaded weight may impose a metabolic demand equivalent to that of fat mass (FM) during load carriage. Males (M) typically have a lower body fat percentage than females (F), resulting in metabolic demand differences during load carriage that may be mitigated by accounting for FM in pack loads. PURPOSE: To determine whether normalizing pack load to FM equalizes metabolic cost across sexes during load carriage. METHODS: Twenty-eight participants (14M, 23 ± 5 y, 1.81 ± 0.07 m, 78.7 ± 10.0 kg, 12.7 ± 5.4% body fat, VO₂peak 4.18 ± 0.54 L·min^-1; 14F, 22 ± 4 …

Wattage- And Composition-Dependent Ocular Surface Toxicity: An In Vitro Study On E-Cigarette Aerosol Exposure In Human Corneal Epithelial Cells, Tzu-Ling Lin

Masters Theses

As electronic cigarette consumption continues to escalate globally, its impact on non-respiratory mucosal surfaces, particularly the ocular surface, remains largely understudied. This study investigated the toxicological effects of e-cigarette aerosols using a human corneal epithelial cell (HCE-2) model. Our findings reveal that aerosol exposure induces a significant, dose-dependent reduction in cell viability, exacerbated by higher device wattage and specific flavor agents such as watermelon. Exposure was found to trigger intracellular oxidative stress and the activation of apoptotic pathways, leading to programmed cell death. Furthermore, the upregulation of proinflammatory cytokines suggests that vaping may predispose users to chronic inflammatory conditions of …

Moth Assemblages Of Fort Leonard Wood, Missouri, Kimberly Anne Steese

Masters Theses

"Moths (Lepidoptera) are ecologically important insects that function as herbivores, pollinators, prey resources, and indicators of ecosystem integrity. Despite their ecological significance, moth communities in the Missouri Ozarks remain poorly documented, particularly within military-managed landscapes. This thesis examined patterns of moth diversity, assemblage structure, and environmental drivers at Fort Leonard Wood (FLW), Missouri, while also assessing the distribution and genetic diversity of species within the genus Papaipema.

Field surveys were conducted from 2019 through 2021 across prairie, savanna, forest, and restoration habitats at FLW using UV bucket traps, sheet trapping, and targeted larval surveys. Across all sampling efforts, 29,116 individual …

A Metabolite-Dependent Mechanism By Which Bifidobacterium Animalis Subsp. Lactis Promotes Bacteroides Colonization, Khashayar Shahin, Liang Wang, Zihan He, Bomin Lv, Arya Van Alin, Richard Lo-Man, Hao Wu, Philippe Sansonetti, Jean Marc Collard

Research outputs 2022 to 2026

Prokaryote-prokaryote symbiotic relationships influence interactions within microbial communities, affecting colonization, survival, and organization. Unlike competition, consortium species facilitate growth via metabolite cross-feeding. This study explored interactions between two early human gut colonizers: partially aerotolerant Bifidobacterium spp. and strict anaerobic Bacteroides spp., using omics techniques. Promotion of Bacteroides spp. growth by Bifidobacterium animalis subsp. lactis was demonstrated through co-culture experiments in anaerobic conditions. Metabolomic analysis revealed over 150 unique metabolites present in B. animalis subsp. lactis supernatants are absent in other Bifidobacterium species, including 3-hydroxycapric acid, D-alanyl-D-alanine, 2-isopropylmalic acid, and D-glucose 2-phosphate. These compounds served as nutritional substrates, including carbon and …