ASU Electronic Theses and Dissertations
This collection includes most of the ASU Theses and Dissertations from 2011 to present. ASU Theses and Dissertations are available in downloadable PDF format; however, a small percentage of items are under embargo. Information about the dissertations/theses includes degree information, committee members, an abstract, supporting data or media.
In addition to the electronic theses found in the ASU Digital Repository, ASU Theses and Dissertations can be found in the ASU Library Catalog.
Dissertations and Theses granted by Arizona State University are archived and made available through a joint effort of the ASU Graduate College and the ASU Libraries. For more information or questions about this collection contact or visit the Digital Repository ETD Library Guide or contact the ASU Graduate College at gradformat@asu.edu.
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Description
Infectious diseases have emerged as a significant threat to wildlife. Environmental change is often implicated as an underlying factor driving this emergence. With this recent rise in disease emergence and the acceleration of environmental change, it is important to identify the environmental factors that alter host-pathogen dynamics and their underlying mechanisms. The emerging pathogen Batrachochytrium dendrobatidis (Bd) is a clear example of the negative effects infectious diseases can have on wildlife. Bd is linked to global declines in amphibian diversity and abundance. However, there is considerable variation in population-level responses to Bd, with some hosts experiencing marked declines while others persist. Environmental factors may play a role in this variation. This research used populations of pond-breeding chorus frogs (Pseudacris maculata) in Arizona to test if three rapidly changing environmental factors nitrogen (N), phosphorus (P), and temperature influence the presence, prevalence, and severity of Bd infections. I evaluated the reliability of a new technique for detecting Bd in water samples and combined this technique with animal sampling to monitor Bd in wild chorus frogs. Monitoring from 20 frog populations found high Bd presence and prevalence during breeding. A laboratory experiment found 85% adult mortality as a result of Bd infection; however, estimated chorus frog densities in wild populations increased significantly over two years of sampling despite high Bd prevalence. Presence, prevalence, and severity of Bd infections were not correlated with aqueous concentrations of N or P. There was, however, support for an annual temperature-induced reduction in Bd prevalence in newly metamorphosed larvae. A simple mathematical model suggests that this annual temperature-induced reduction of Bd infections in larvae in combination with rapid host maturation may help chorus frog populations persist despite high adult mortality. These results demonstrate that Bd can persist across a wide range of environmental conditions, providing little support for the influence of N and P on Bd dynamics, and show that water temperature may play an important role in altering Bd dynamics, enabling chorus frogs to persist with this pathogen. These findings demonstrate the importance of environmental context and host life history for the outcome of host-pathogen interactions.
ContributorsHyman, Oliver J. (Author) / Collins, James P. (Thesis advisor) / Davidson, Elizabeth W. (Committee member) / Anderies, John M. (Committee member) / Elser, James J. (Committee member) / Escalante, Ananias (Committee member) / Arizona State University (Publisher)
Created2012
Description
Salivary cortisol is the least invasive way in measuring hormonal response during exercise without interruption. In nationally ranked fencers (n=21), changes in cortisol were monitored by measurement of salivary cortisol sampled throughout different rounds of three North American Cup tournaments during the 2017-2018 United States fencing season. The changes were also compared when looking at if a bout ended in a victory or defeat; the difference in rank between opponents; and the difference in score at the end of the bout. Immediately before the tournament cortisol levels were sampled, changes were in comparison to the initial sample as well as change from one bout to the next. The primary purpose of this study was to (a) compare how cortisol levels fluctuate during a tournament and (b) analyze cortisol levels to see if there is an optimal rage for performance. Eustress, “good stress” was considered optimal when the athletes were at peak performance. Here, peak performance means accomplishing the task, with the task being the bout ending in a victory. It was hypothesized that (a) cortisol levels would peak after a loss or stressful bout and (b) there would be an optimal range of cortisol for peak performance. This study supports the findings that cortisol peaks after a loss, and could point to optimal cortisol levels being more of an individualized range for each athlete. If these athletes can explicitly see just how their hormones rise and fall, then perhaps being more aware of these levels and being able to embrace them could lead to peak performance.
ContributorsVie, Jerica Nicole (Author) / Baluch, D. Page (Thesis advisor) / Sterner, Beckett (Committee member) / Cataldo, Donna (Committee member) / Arizona State University (Publisher)
Created2018
Description
The complex life cycle and widespread range of infection of Plasmodium parasites, the causal agent of malaria in humans, makes them the perfect organism for the study of various evolutionary mechanisms. In particular, multigene families are considered one of the main sources for genome adaptability and innovation. Within Plasmodium, numerous species- and clade-specific multigene families have major functions in the development and maintenance of infection. Nonetheless, while the evolutionary mechanisms predominant on many species- and clade-specific multigene families have been previously studied, there are far less studies dedicated to analyzing genus common multigene families (GCMFs). I studied the patterns of natural selection and recombination in 90 GCMFs with diverse numbers of gene gain/loss events. I found that the majority of GCMFs are formed by duplications events that predate speciation of mammal Plasmodium species, with many paralogs being neutrally maintained thereafter. In general, multigene families involved in immune evasion and host cell invasion commonly showed signs of positive selection and species-specific gain/loss events; particularly, on Plasmodium species is the simian and rodent clades. A particular multigene family: the merozoite surface protein-7 (msp7) family, is found in all Plasmodium species and has functions related to the erythrocyte invasion. Within Plasmodium vivax, differences in the number of paralogs in this multigene family has been previously explained, at least in part, as potential adaptations to the human host. To investigate this I studied msp7 orthologs in closely related non-human primate parasites where homology was evident. I also estimated paralogs’ evolutionary history and genetic polymorphism. The emerging patterns where compared with those of Plasmodium falciparum. I found that the evolution of the msp7 multigene family is consistent with a Birth-and-Death model where duplications, pseudogenization and gene lost events are common. In order to study additional aspects in the evolution of Plasmodium, I evaluated the trends of long term and short term evolution and the putative effects of vertebrate- host’s immune pressure of gametocytes across various Plasmodium species. Gametocytes, represent the only sexual stage within the Plasmodium life cycle, and are also the transition stages from the vertebrate to the mosquito vector. I found that, while male and female gametocytes showed different levels of immunogenicity, signs of positive selection were not entirely related to the location and presence of immune epitope regions. Overall, these studies further highlight the complex evolutionary patterns observed in Plasmodium.
ContributorsCastillo Siri, Andreina I (Author) / Rosenberg, Michael (Thesis advisor) / Escalante, Ananias (Committee member) / Taylor, Jesse (Committee member) / Collins, James (Committee member) / Arizona State University (Publisher)
Created2016
Description
Evolution is a key feature of undergraduate biology education: the AmericanAssociation for the Advancement of Science (AAAS) has identified evolution as one of
the five core concepts of biology, and it is relevant to a wide array of biology-related
careers. If biology instructors want students to use evolution to address scientific
challenges post-graduation, students need to be able to apply evolutionary principles to
real-life situations, and accept that the theory of evolution is the best scientific
explanation for the unity and diversity of life on Earth. In order to help students progress
on both fronts, biology education researchers need surveys that measure evolution
acceptance and assessments that measure students’ ability to apply evolutionary concepts.
This dissertation improves the measurement of student understanding and acceptance of
evolution by (1) developing a novel Evolutionary Medicine Assessment that measures
students’ ability to apply the core principles of Evolutionary Medicine to a variety of
health-related scenarios, (2) reevaluating existing measures of student evolution
acceptance by using student interviews to assess response process validity, and (3)
correcting the validity issues identified on the most widely-used measure of evolution
acceptance - the Measure of Acceptance of the Theory of Evolution (MATE) - by
developing and validating a revised version of this survey: the MATE 2.0.
ContributorsMisheva, Anastasia Taya (Author) / Brownell, Sara (Thesis advisor) / Barnes, Elizabeth (Committee member) / Collins, James (Committee member) / Cooper, Katelyn (Committee member) / Sterner, Beckett (Committee member) / Arizona State University (Publisher)
Created2023
Description
Increasingly, college courses have transitioned from traditional lecture to student-centered active learning, creating more opportunities for students to interact with each other in class. Recent studies have indicated that these increased interactions in active learning can create situations where students’ identities are more salient, which could result in novel challenges for students with marginalized identities. Christianity has been shown to be a marginalized identity in the context of undergraduate biology courses, but it is unknown whether Christian students experience challenges in their interactions with other students in class. The social psychology framework of concealable stigmatized identity (CSI) was used to explore the experiences of Christian students during peer interactions in undergraduate biology courses. Thirty students were interviewed, and most felt their religious identity was salient during peer interactions in biology. Students also reported that they have more opportunities to reveal their religious identity in courses that incorporate peer discussion than in courses that do not. Students claimed that revealing their religious identity to their peers could be beneficial because they could find other religious students in their courses, grow closer with their peers, and combat stereotypes about religious individuals in science. Though most students anticipated stigma, which caused some students to choose not to reveal their religious identities, comparatively few had experienced stigma during peer interactions in their college biology courses, and even fewer had experienced stigma from peers who knew they were religious. These findings indicate that it be may important to teach students how to be culturally competent to reduce Christian students’ anticipated and experienced stigma in active learning courses.
ContributorsEdwards, Baylee Anne (Author) / Brownell, Sara E. (Thesis advisor) / Barnes, M. Elizabeth (Committee member) / Sterner, Beckett (Committee member) / Cooper, Katelyn M. (Committee member) / Arizona State University (Publisher)
Created2022