Master of Science in Integrated Biosciences Theses

Persistent link for this collectionhttps://hdl.handle.net/11299/275127

This collection contains some of the theses produced by University of Minnesota Duluth master's degree students in the University of Minnesota systemwide Master of Science in Integrated Biosciences graduate program. Additional theses (also known as Plan As) can be found in the University of Minnesota Twin Cities Dissertations and Theses collection.

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Now showing 1 - 6 of 6

Exploring the impact of a perfluoroalkyl substance (PFAS) and interspecific variation in passerine metabolism
(2025) Smith, Angelica
A comprehensive understanding of physiology is essential for improving risk assessment and management as organisms face compounding stressors, such as environmental contaminants and climate change. Passerines are a diverse and abundant group of birds that are sometimes vulnerable to environmental stressors, making it important to study their physiological responses in greater detail. I approached this challenge by using field flow-through respirometry, a novel method in this context, to investigate the effects of a perfluoroalkyl substance (PFAS), perfluorooctane sulfonate (PFOS), on the metabolic regulation and thyroid function of Tree Swallows (Tachycineta bicolor). Additionally, interspecific differences were examined in metabolic rates and liver weights among three passerine species in northern Minnesota: Tree Swallows, Northern House Wrens (Troglodytes aedon), and Black-capped Chickadees (Poecile atricapillus). It was found that PFOS exposure impacts thyroid hormone concentrations in Tree Swallows but does not significantly impact metabolic rate or growth. Furthermore, interspecific differences in metabolic rates and liver weights were significant, and liver weight may be better at explaining differences in metabolic rate than whole animal mass alone. This integrative study contributes to both an understanding of ecotoxicological impacts of PFAS and a foundation for future comparative physiology studies in passerines.
Would you rather be sexy or healthy? relationships between the immune system and coloration in Common Redpolls (Acanthis flammea)
(2025) Swanson, Erika
Birds have long been studied as examples of sexual selection. There are many traits that can point to a bird’s quality as a mate, such as song, dance, and elaborate plumage features. Each of these traits has an energetic cost, and carotenoid-based plumage is one such trait. Carotenoid pigments are responsible for most yellow, orange, and red feathers, and almost a quarter of all bird species display carotenoid-based coloration. However, because carotenoids are only directly synthesized by plants, algae, and some fungi, birds must accumulate them in their diets before depositing them into their feathers. The pathway to produce red feathers, such as those displayed by Common Redpolls (Acanthis flammea), is more recently evolved and includes more carotenoid modification steps—and a potentially higher energetic cost—than yellow plumage. If a bird has enough energy to both produce these feathers and remain healthy, the plumage is an honest signal of quality. Conversely, if the bird is putting more energy towards plumage and gaining a mate, there may be a cost that affects other systems, such as the function of the immune system. Although limited, there have been studies conducted linking carotenoids and coloration to a stronger immune system and better condition. This work examines trends between coloration, body metrics, and immune system function in Common Redpolls to determine if plumage production is a direct signal of health. Ultimately, we found that the plumage coloration of redpolls is an honest signal of their health. Cap size in both males and females demonstrates immune health, where larger caps correlate with a stronger immune system. Also, redder breast coloration in mature males shows stronger humoral immunity.
Comparative RNA-seq analysis of fetal/neonatal iron deficient and thyroid hormone deficient neonatal rat brain and liver
(2024-12) Hanson, Benjamin
Thyroid hormone deficiency and iron deficiency are two prevalent nutritional disorders that significantly impact neonatal development, particularly in the context of brain. This study investigates the unique and overlapping effects of these deficiencies on gene expression in the context of neurodevelopment. Our findings reveal that TH deficiency leads to the downregulation of several key genes involved in peroxisomal lipid metabolism, particularly those associated with beta-oxidation. This downregulation compromises the liver's capacity to oxidize fatty acids, resulting in reduced ketone body production. Similarly, iron deficiency triggers a metabolic switch from fatty acid beta-oxidation to glycolytic dependence, with significant downregulation of genes involved in ketogenesis and upregulation of glycolytic genes. We also found that there is a compounded effect on myelination and extracellular matrix organization, essential for neuronal connectivity and function. Notably, the study highlights the role of insulin-like growth factor signaling, which is significantly perturbed in both deficiencies, linking liver function to neurodevelopmental outcomes. The implications of these findings underscore the necessity for early detection and intervention strategies in populations at risk for TH and iron deficiencies, particularly in neonates. Future research should focus on elucidating the molecular mechanisms underlying these interactions and their long-term impacts on cognitive and motor development.
Drivers of reproductive variability in Vaccinium cespitosum and vaccinium vitis-idaea in northeastern Minnesota
(2024-07) Hainlen, David
Multiple factors affect reproductive variability within a population, and understanding these factors is important for making informed land management decisions. I investigated how clonality impacts reproductive variability in Vaccinium cespitosum and Vaccinium vitis-idaea (Ericaceae), and how the history of land management affects reproductive variability in V. cespitosum. Vaccinium populations with a history of land management are expected to have higher reproductive potential than populations that have not been managed, as land management has been shown to positively impact stem, flower, and fruit production. Additionally, both species are partially clonal and are capable of sexual or clonal reproduction. In populations with high clone densities, the likelihood of self-pollination via geitonogamy and subsequent early-acting inbreeding depression increases. Potential impacts due to early acting inbreeding depression include reduced fruit production and reduced fecundity of populations, which reduces the efficacy of land management. I established multiple survey sites (populations) in northeastern and northcentral Minnesota and collected measures of sexual reproductive effort (proportion of flowering ramets and number of flowers per ramet) and sexual reproductive success (percent fruit set, proportion of viable to inviable seeds, and berry mass and diameter) for both species. For V. cespitosum, populations were selected based on contrasting disturbed vs established land management histories. Between study years, land management history and clonality were not significant predictors of reproductive effort or subsequent success. There is a complex interplay of many factors, both large scale, such as yearly climatic conditions and geographic range, and small scale, such as soil nutrient quality, that likely interact to influence reproductive variability among our populations.
The Breeding Ecology of Boreal Chickadees in the Red Lake Wildlife Management Area in Northern Minnesota
(2023-08) Snow, Kara
We examined the impacts of fragmentation on the breeding ecology of the Boreal Chickadee (Poecile hudsonicus) in the Red Lake WMA in Minnesota. Boreal Chickadees are listed as a Species in Greatest Conservation Need (SGCN), with declines attributed to habitat loss, degradation and fragmentation. We used linear mixed-effect models to examine the impacts of fragmentation on Boreal Chickadee food availability, nestling growth rates, body condition and provisioning rates. We modeled nest survival in relation to landscape, patch and nest site scale metrics of fragmentation using the program MCEstimate. We found evidence that fragmentation negatively impacts nest survival, nestling growth rates and food availability. Additionally, we elucidated the diet of nestling Boreal Chickadees by extracting DNA from fecal samples and using DNA metabarcoding techniques. We found that Boreal Chickadee nestlings are primarily being provisioned prey from the orders: Lepidoptera, Aranea and Diptera; and are likely actively selecting for Lepidoptera.
Cloacal swabbing as a tool to study diet in migrating raptors using DNA metabarcoding
(2021-05) Brouellette, Lisa
While much research has gone into understanding the timing and patterns of migration, little has been done to understand the diet of raptors during migration. Most raptor dietary studies focus on the breeding season or winter, but migratory diet may be quite different due to differences in habitat type and prey availability along migration flyways. Here, we tested the efficacy of DNA metabarcoding to detect prey DNA on cloacal swabs. In 2019, we collected cloacal swabs from raptors during spring and fall migration in Duluth, MN. We analyzed 287 cloacal swabs from 11 species of raptors. We hypothesized that detection of dietary DNA on cloacal swabs would be influenced by the species of raptor swabbed, the size of the raptor, and migratory flight strategy (passive/soaring flight vs. active flight). Prey DNA was detected on 18.46% of cloacal swabs. Using a generalized linear model, we found that neither species, size, nor migratory flight strategy were better than the null model at explaining differences in detection of dietary DNA. To our knowledge, this is the first study to use cloacal swabbing and DNA metabarcoding to detect dietary DNA and our results indicate that this method has potential for further use.

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