Theses and Dissertations
This collection includes both ASU Theses and Dissertations, submitted by graduate students, and the Barrett, Honors College theses submitted by undergraduate students.
Displaying 41 - 43 of 43
Description
Speciation, or the process by which one population diverges into multiple populations that can no longer interbreed with each other, has brought about the incredible diversity of life. Mechanisms underlying this process can be more visible in the early stages of the speciation process. The mechanisms that restrict gene flow in highly mobile species with no absolute barriers to dispersal, especially marine species, are understudied. Similarly, human impacts are reshaping ecosystems globally, and we are only just beginning to understand the implications of these rapid changes on evolutionary processes. In this dissertation, I investigate patterns of speciation and evolution in two avian clades: a genus of widespread tropical seabirds (boobies, genus Sula), and two congeneric passerine species in an urban environment (cardinals, genus Cardinalis). First, I explore the prevalence of gene flow across land barriers within species and between sympatric species in boobies. I found widespread evidence of gene flow over all land barriers and between 3 species pairs. Next, I compared the effects of urbanization on the spatial distributions of two cardinal species, pyrrhuloxia (Cardinalis sinuatus) and northern cardinals (Cardinalis cardinalis), in Tucson, Arizona. I found that urbanization has different effects on the spatial distributions of two closely related species that share a similar environmental niche, and I identified environmental variables that might be driving this difference. Then I tested for effects of urbanization on color and size traits of these two cardinal species. In both of these species, urbanization has altered traits involved in signaling, heat tolerance, foraging, and maneuverability. Finally, I tested for evidence of selection on the urban populations of both cardinal species and found evidence of both parallel selection and introgression between the species, as well as selection on different genes in each species. The functions of the genes that experienced positive selection suggest that light at night, energetics, and air pollution may have acted as strong selective pressures on these species in the past. Overall, my dissertation emphasizes the role of introgression in the speciation process, identifies environmental stressors faced by wildlife in urban environments, and characterizes their evolutionary responses to those stressors.
ContributorsJackson, Daniel Nelson (Author) / McGraw, Kevin J (Thesis advisor) / Amdam, Gro (Committee member) / Sweazea, Karen (Committee member) / Taylor, Scott (Committee member) / Arizona State University (Publisher)
Created2023
Description
The desire to start a family is something millions of people around the globe strive to achieve. However, many factors such as the societal changes in family planning due to increasing maternal age, use of birth control, and ever-changing lifestyles have increased the number of infertility cases seen in the United States each year. Infertility can manifest as a prolonged inability to conceive, or inability to carry a pregnancy full-term. Modern advancements in the field of reproductive medicine have begun to promote the use of Assisted Reproductive Technologies (ART) to circumvent reduced fertility in both men and women. Implementation of techniques such as In Vitro Fertilization, Intracytoplasmic Sperm Injection, and Pre-Implantation Genetic Testing have allowed many couples to conceive. There is continual effort being made towards developing more effective and personalized fertility treatments. This often begins in the form of animal research—a fundamental step in biomedical research. This dissertation examines infertility as a medical condition through the characterization of normal reproductive anatomy and physiology in the introductory overview of reproduction. Specific pathologies of male and female-factor infertility are described, which necessitates the use of ARTs. The various forms of ARTs currently utilized in a clinical setting are addressed including history, preparations, and protocols for each technology. To promote continual advancement of the field, both animal studies and human trials provide fundamental stepping-stones towards the execution of new techniques and protocols. Examples of research conducted for the betterment of human reproductive medicine are explored, including an animal study conducted in mice exploring the role of tyramine in ovulation. With the development and implementation of new technologies and protocols in the field, this also unearths ethical dilemmas that further complicate the addition of new technologies in the field. Combining an extensive review in assisted reproduction, research and clinical fieldwork, this study investigates the history and development of novel research conducted in reproductive medicine and explores the broader implications of new technologies in the field.
ContributorsPeck, Shelbi Marie (Author) / Baluch, Debra P (Thesis advisor) / Maienschein, Jane (Thesis advisor) / Sweazea, Karen (Committee member) / Ellison, Karin (Committee member) / Arizona State University (Publisher)
Created2021
Description
Chronic low-grade inflammation is a main pathogenic link between obesity and Type 2 Diabetes (T2D) and a putative target for treatment. While a wide array of pharmacologic agents is available to manage T2D, many patients still face perturbed glycemia and subclinical inflammation. Therefore, complementary nutraceutical strategies that target inflammation, metabolism, and resolution physiology hold promise as adjunctive options to quell the disturbed immuno-metabolic milieu observed in T2D. Omega-3 polyunsaturated fatty acids (PUFAs) and anthocyanins are two dietary components evidenced to mitigate inflammation and improve T2D risk factors, through distinct and similar targets. However, the combined use of such nutraceuticals has not yet been examined in individuals with T2D. This dissertation leveraged data from a larger randomized, double-blind, placebo-controlled trial conducted between January 2022—September 2023 investigating the use of combined supplementation (active treatment; [FOM]) of anthocyanins (600 mg/d maqui berry extract) and omega-3 PUFAs (3 g/day fish oil; 2 g/d EPA, 1 g/d DHA) for 8 weeks on cytokines and mental acuity in individuals with T2D, compared to a placebo (CON). The current study examined the effects of this supplemental strategy on markers of metabolic inflammation, oxidative stress, and cardiometabolic risk. The results indicated that a marker of sustained omega-3 dietary intake and tissue accumulation termed the Omega-3 Index was inversely associated with HbA1c (? = -8.5, 95%CI -15.1, -1.4, p = 0.022) and glucose (? = -12.4, 95%CI -22.9, -0.5, p = 0.042), after adjustment for covariates at baseline across all participants with T2D in this study. However, outcomes from linear mixed model analyses demonstrated that there were no significant differences in change from baseline between FOM and CON groups at week 8 in any of the inflammatory, oxidative stress, glycemic control, or circulating lipid markers assessed in this study. These null effects were observed despite a 93% greater increase from baseline in the Omega-3 Index observed in the FOM group compared to the CON group at week 8. Therefore, the findings do not support significant treatment effects associated with 2 months of combined marine omega-3 PUFAs and maqui berry extract on inflammatory and cardiometabolic outcomes in individuals with T2D.
ContributorsFessler, Samantha Nicole (Author) / Johnston, Carol S (Thesis advisor) / Sweazea, Karen (Committee member) / Wang, Shu (Committee member) / Kavouras, Stavros A (Committee member) / Grimm, Kevin J (Committee member) / Arizona State University (Publisher)
Created2024