<p>A saugeye is the progeny of a female walleye (<i>Sander vitreus)</i> and male sauger (<i>Sander canadensis)</i>. In the United States, hybrid saugeyes are considered important for recreational fisheries and as a potential food source. Saugeyes grow exceptionally faster than their non-hybrid parents and are more tolerant of a broader range of water conditions. They are also of interest to anglers due to their increased growth rate and ease to catch. Rather unexpectedly, biologists have recently observed fish that they believe to be saugeye in the Fort Wayne Rivers even though only walleye have been stocked in the area. The fish in Hurshtown Reservoir are believed to be walleye and the identification of those in the Three Rivers is unknown. A potential source for saugeye in the Fort Wayne Rivers is St. Marys State Fish Hatchery in Ohio. This research aims to determine if the fish found in the Fort Wayne Rivers are walleye or saugeye using microsatellite analysis. Microsatellites at seven loci were genotyped for 20 reference walleye, sauger, and saugeye as well as 21 unknown fish caught near Fort Wayne. Of the fish caught near Fort Wayne, three are from Hurshtown Reservoir and 18 are from the Three Rivers. Assignment tests of genotypes were completed using model and non-model based cluster analysis. Genotypic variation clearly resolved the two parent species from their hybrid offspring. Sixteen of eighteen <i>Sander</i> (unknown species) caught in Fort Wayne Rivers between 2018 and 2019 were determined to be first generation saugeye. The other two were walleye found in the Maumee River downstream of Hosey Dam. The three <i>Sander</i> caught in Hurshtown Reservoir were verified to be walleye. Sauger have never been stocked in the Fort Wayne Rivers and connecting waterways. Therefore, it is not likely that the saugeye found in the analysis are from natural reproduction. It is speculated that saugeye are swimming to Fort Wayne from hatcheries within the Maumee watershed. There are many potential sources for walleye in the Fort Wayne Rivers. </p>

<p>  </p> <p>Many species of turtle are facing serious declines from multiple anthropogenic causes. One such turtle native to the United States, the Blanding’s Turtle (<em>Emydoidea blandingii</em>), has faced declines in nearly every sector of their range, yet few populations have known recorded demographics, such as abundance, density, sex ratio, and body sizes. To inform managers of these crucial demographic measures of three spatially adjacent populations on Camp Grayling, MI, I implemented a capture-mark-recapture study from 2021 to 2022. I calculated Lincoln-Petersen Index and ran constant, time-varying, and behavioral response models for both full and conditional likelihoods in Program MARK. All best fit models estimated populations ≥30. The three populations sampled at Camp Grayling were low in abundance, densities, and biomass compared to some more well-known populations. Adult body weight means were 1456 g and 1223 g for males and females, respectively. Mean carapace lengths for males was 22.42 cm and females were 20.11 cm. The males of these populations were significantly larger than the mean found across the Blanding’ Turtles range. There is evidence of recruitment within these populations. A long-term research plan should be implemented and focus on investigating connectedness of these populations, as well as building data for population viability analyses. Additionally, immediate conservation action should take place to protect this vulnerable species.</p>

<p dir="ltr">Bat population numbers are declining in the Midwestern United States. Reasons for decline are multifaceted (habitat degradation, fatalities at wind turbines, White Nose Syndrome, and declining insect populations), and many species are listed as endangered (Myotis sodalis, Myotis septentrionalis, Perimyotis subflavus). Other species in the Midwestern United States have no conservation status (Eptesicus fuscus), or are only listed as a species of concern (Lasiurus cinereus, Lasiurus borealis, Lasionycteris noctivagans). Bats play a crucial role in our ecosystems, providing both ecological and economic benefit as pollinators and insect population regulators. Thus, conserving these species is vital. To gain better insight into the ecology of Midwestern bat species I studied five species in two respects. First, I investigated the availability of roosts for a colony of endangered Myotis sodalis near Indianapolis. This colony has withstood high levels of urbanization and habitat degradation. Therefore, understanding what aspects of the roosting area has allowed for continued use by the colony is crucial for future conservation efforts. I used an Akaike’s Information Criteria approach to rank models that best differentiate between the current roosting area and surrounding landscape. I identified that the roosting area contained a greater number of large standing dead trees (Snags >42.6 cm) that are able to serve as primary roosts for the colony. These results demonstrate that a colony of Indiana bats may be able to withstand urbanization if they have enough large DBH snags available in the area. Future conservation efforts in a heavily urbanized environment should focus on the maintaining large snags as primary roosts. Second, I studied the morphological variation of four species (Lasiurus cinereus, Lasiurus borealis, Lasionycteris noctivagans, and Eptesicus fuscus) to parse out differences that may lead to niche specialization. These four species share habitat and foraging range and therefore may directly compete for resources. However, despite declining insect populations these four species have moderately stable populations. I collected approximately 30 craniums and mandibles for each species and compared the linear size differences between landmarks and the overall shape variation from these landmarks. Due to different phylogenies and body sizes, the four species were different from one another in all 24 linear measurements. In regards to shape variation, the Eptesicini bat craniums had characteristics of more gracile species. In addition, the mandibles of Eptesicini were highly distinct. Lasionycteris noctivagans was the least durable and Eptesicus fuscus had 10 specialization for hard bodied prey consumption. These results suggest potential niche specialization due variation in morphology.</p>

<p> Per- and polyfluoroalkyl substances (PFAS) are a class of persistent environmental contaminants that have become ubiquitous, resulting in widespread exposure among humans and wildlife. Amphibians are regularly exposed in the field, making them susceptible to sublethal effects of PFAS exposure. In amphibians exposed to PFAS, deleterious effects have been observed, including reduction in body condition measured using the scaled mass index (SMI) and degraded hepatic condition, among others. PFAS may dysregulate lipid metabolism by altering signaling cascades regulated by peroxisome proliferator activated receptors (PPAR), but whether changes in energy stores can explain changes in amphibian SMI and/or hepatic condition remain underexplored. Since lipids are a critical energy reserve for anurans, understanding whether lipid metabolism is being perturbed is critical. The central objective of this thesis was to investigate the effect of PFAS on lipid homeostasis in <em>Xenopus laevis </em>tadpoles within the context of a PPAR mechanism of action (MOA), considering apical, molecular, and lipidomic endpoints. I conducted three studies: (a) a study to characterize SMI and the relative expression of the hepatic xPPARα/β/γ during metamorphosis, (b) a pharmaceutical exposure to assess the <em>in vivo</em> effects of xPPARα/β/γ agonism on hepatic gene expression for select downstream targets (<em>apoa5, fabp1, acox1,​ pck1</em>), and (c) a chronic PFAS exposure to investigate the effects of environmentally relevant concentrations (PFOS, PFHxS, PFOA, PFHxA at 0.5 ppb; binary mixture of PFOS:PFHxS at 1 ppb) on lipid homeostasis through apical endpoints (mass, snout vent length, SMI, hepatic condition), relative hepatic gene expression, and Multiple Reaction Monitoring (MRM) profiling of the hepatic lipidome for changes in relative class abundance. In study (a), I identified SMI and hepatic expression of <em>xPPARα/β/γ</em> is dynamic during late metamorphosis, indicating the potential for heightened susceptibility. However, in study (b), pharmaceutical agonists had no effect on <em>X. laevis</em> at high doses. For study (c), I did not observe effects on a majority of apical endpoints, including SMI, but detected a significant sex-specific reduction in hepatic condition for male<em> X. laevis</em> tadpoles exposed to single-chemical perfluorosulfonic acid (PFSA) treatments. For gene expression, I observed a transient downregulation for apolipoprotein-V (<em>apoa5</em>) at Nieuwkoop and Faber (NF) stage 62 for <em>X. laevis</em> tadpoles exposed to single-chemical perfluorocarboxylic acid (PFCA) treatments. Lipid profiling detected transient dysregulation of predominantly membrane lipids in-response to short-chain PFAS treatments at NF 58. Overall, our findings indicate PFAS may exert toxicity during anuran metamorphosis through multiple mechanisms of action (MOA) with sex-specific and developmental-stage specific outcomes.</p>

<p dir="ltr">Primary cilia are hair-like structures found on nearly all mammalian cell types, including cells in the developing and adult brain. Cilia establish a unique signaling compartment for cells. For example, a diverse set of receptors and signaling proteins localize within cilia to regulate many physiological and developmental pathways including the Hh pathway. Defects in cilia structure, protein localization, or cilia function lead to genetic disorders called ciliopathies, which present with various clinical features including several neurodevelopmental phenotypes and hyperphagia associated obesity. Despite their dysfunction being implicated in several disease states, understanding their roles in CNS development and signaling has proven challenging. I hypothesize that dynamic changes to ciliary protein composition contributes to this challenge and may reflect unrecognized diversity of CNS cilia. The proteins ARL13B and ADCY3 are established ciliary proteins in the brain and assessing their localization is often used in the field to visualize cilia. ARL13B is a regulatory GTPase important for regulating cilia structure, protein trafficking, and Hh signaling, while ADCY3 is a ciliary adenylyl cyclase thought to be involved in ciliary GPCR singaling. Here, I examine the ciliary localization of ARL13B and ADCY3 in the perinatal and adult mouse brain by defining changes in the proportion of cilia enriched for ARL13B and ADCY3 depending on brain region and age. Furthermore, I identify distinct lengths of cilia within specific brain regions of male and female mice. As mice age, ARL13B cilia become relatively rare in many brain regions, including the hypothalamic feeding centers, while ADCY3 becomes a prominent cilia marker. It is important to understand the endogenous localization patterns of these proteins throughout development and under different physiological conditions as these common cilia markers may be more dynamic than initially expected. Understanding regional and development associated cilia signatures and physiological condition cilia dynamic changes in the CNS may reveal molecular mechanisms associated with ciliopathy clinical features such as obesity.</p>

<p>Management of predation on sea turtle nesting beaches is vital to conservation efforts for the vulnerable loggerhead turtles (<i>Caretta caretta</i>) and olive ridley turtles (<i>Lepidochelys olivacea</i>). Sea turtles increasingly face threats from invasive and human-tolerant mammalian predators as human disturbances on nesting beaches rises. The intensity of mammalian predation has increased in Las Baulas National Park in Costa Rica which is an important nesting site for several species of threatened and endangered sea turtles. I analyzed loggerhead and olive ridley nest predation on four beaches in the United States and Costa Rica that were chosen for variations in degree of human disturbance and management strategies. My objectives were to 1) determine if egg predation rates differ at the four sites, 2) determine the most destructive predators at each location, and 3) suggest management options to alleviate mammalian threats to turtle clutches on Playa Grande and Playa Cabuyal in Costa Rica. My results show that the beaches without a nest protection or predator control program had very high rates of predation. Invasive mammalian predators and mammalian predators associated with human disturbance were the most destructive at the four sites. I recommend that regulations regarding dogs and the take of eggs from the beach are enforced at Playa Cabuyal and that physical nest protection is rapidly implemented at Playa Grande. I also recommend that the National Park consider managing raccoon predation by removing problem individuals, but caution that they do so in a way that maintains the animals’ role in the ecosystem.</p>

<p dir="ltr">The aquaculture industry has experienced remarkable expansion over the past few decades, largely due to the development of modern technologies and intensive farming systems. However, as the industry continues to grow, farming-related and environmental stressors such as overcrowding, poor water conditions and handling have continued to pose major obstacles to the worldwide expansion of this sector. The presence of these stressors affect the growth potential and health of farmed animals leading to significant economic losses. Hence, efficient management of the stress response of farmed species via sustainable means is important to ensure continuous development of the aquaculture sector. This study, therefore, explores the potential of dietary tryptophan supplementation to mitigate stress and improve growth, immune response, and disease resistance in channel catfish (<i>Ictalurus punctatus</i>). The study comprised a 36-day feeding trial where juvenile catfish were fed a tryptophan-supplemented diet under stressed (cortisol-supplemented) and unstressed conditions, followed by a 72-hour disease challenge with <i>Aeromonas hydrophila </i>(vAh). At the end of the study, the results show tryptophan supplementation did not significantly enhance growth or nutrient utilization, likely due to its neuroendocrine effects on feed intake. However, tryptophan demonstrated potential in modulating stress physiology and immune responses, including upregulation of key immune-related genes post-infection and promoting survival against vAh infection. These findings suggest that while tryptophan may not directly improve growth in our specific experimental conditions, its role in stress and immune regulation warrants further investigation, particularly in optimizing its dosage and combination with other dietary additives.</p>