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
The coordination of group behavior in the social insects is representative of a broader phenomenon in nature, emergent biological complexity. In such systems, it is believed that large-scale patterns result from the interaction of relatively simple subunits. This dissertation involved the study of one such system: the social foraging of the ant Temnothorax rugatulus. Physically tiny with small population sizes, these cavity-dwelling ants provide a good model system to explore the mechanisms and ultimate origins of collective behavior in insect societies. My studies showed that colonies robustly exploit sugar water. Given a choice between feeders unequal in quality, colonies allocate more foragers to the better feeder. If the feeders change in quality, colonies are able to reallocate their foragers to the new location of the better feeder. These qualities of flexibility and allocation could be explained by the nature of positive feedback (tandem run recruitment) that these ants use. By observing foraging colonies with paint-marked ants, I was able to determine the `rules' that individuals follow: foragers recruit more and give up less when they find a better food source. By altering the nutritional condition of colonies, I found that these rules are flexible - attuned to the colony state. In starved colonies, individual ants are more likely to explore and recruit to food sources than in well-fed colonies. Similar to honeybees, Temmnothorax foragers appear to modulate their exploitation and recruitment behavior in response to environmental and social cues. Finally, I explored the influence of ecology (resource distribution) on the foraging success of colonies. Larger colonies showed increased consistency and a greater rate of harvest than smaller colonies, but this advantage was mediated by the distribution of resources. While patchy or rare food sources exaggerated the relative success of large colonies, regularly (or easily found) distributions leveled the playing field for smaller colonies. Social foraging in ant societies can best be understood when we view the colony as a single organism and the phenotype - group size, communication, and individual behavior - as integrated components of a homeostatic unit.
ContributorsShaffer, Zachary (Author) / Pratt, Stephen C (Thesis advisor) / Hölldobler, Bert (Committee member) / Janssen, Marco (Committee member) / Fewell, Jennifer (Committee member) / Liebig, Juergen (Committee member) / Arizona State University (Publisher)
Created2014
Description
Corporations in biomedicine hold significant power and influence, in both political and personal spheres. The decisions these companies make about ethics are critically important, as they help determine what products are developed, how they are developed, how they are promoted, and potentially even how they are regulated. In the last fifteen years, for-profit private companies have been assembling bioethics committees to help resolve dilemmas that require informed deliberation about ethical, legal, scientific, and economic considerations. Private sector bioethics committees represent an important innovation in the governance of emerging technologies, with corporations taking a lead role in deciding what is ethically appropriate or problematic. And yet, we know very little about these committees, including their structures, memberships, mandates, authority, and impact. Drawing on an extensive literature review and qualitative analysis of semi-structured interviews with executives, scientists and board members, this dissertation provides an in-depth analysis of the Ethics and Public Policy Board at SmithKline Beecham, the Ethics Advisory Board at Advanced Cell Technology, and the Bioethics Committee at Eli Lilly and offers insights about how ideas of bioethics and governance are currently imagined and enacted within corporations. The SmithKline Beecham board was the first private sector bioethics committee; its mandate was to explore, in a comprehensive and balanced analysis, the ethics of macro trends in science and technology. The Advanced Cell Technology board was created to be like a watchdog for the company, to prevent them from making major errors. The Eli Lilly board is different than the others in that it is made up mostly of internal employees and does research ethics consultations within the company. These private sector bioethics committees evaluate and construct new boundaries between their private interests and the public values they claim to promote. Findings from this dissertation show that criticisms of private sector bioethics that focus narrowly on financial conflicts of interest and a lack of transparency obscure analysis of the ideas about governance (about expertise, credibility and authority) that emerge from these structures and hamper serious debate about the possible impacts of moving ethical deliberation from the public to the private sector.
ContributorsBrian, Jennifer (Author) / Robert, Jason S (Thesis advisor) / Maienschein, Jane (Committee member) / Hurlbut, James B (Committee member) / Sarewitz, Daniel (Committee member) / Brown, Mark B. (Committee member) / Moreno, Jonathan D. (Committee member) / Arizona State University (Publisher)
Created2012
Description
Here I present a phylogeographic study of at least six reproductively isolated lineages of harvester ants within the Pogonomyrmex barbatus and P. rugosus species group. The genetic and geographic relationships within this clade are complex: four of the identified lineages are divided into two pairs, and each pair has evolved under a mutualistic system that necessitates sympatry. These paired lineages are dependent upon one another because interlineage matings within each pair are the sole source of hybrid F1 workers; these workers build and sustain the colonies, facilitating the production of the reproductive caste, which results solely from intralineage fertilizations. This system of genetic caste determination (GCD) maintains genetic isolation among these closely related lineages, while simultaneously requiring co-expansion and emigration as their distributions have changed over time. Previous studies have also demonstrated that three of the four lineages displaying this unique genetic caste determination phenotype are of hybrid origin. Thus, reconstructing the phylogenetic and geographic history of this group allows us to evaluate past insights and plan future inquiries in a more complete historical biogeographic context. Using mitochondrial DNA sequences sampled across most of the morphospecies' ranges in the U.S. and Mexico, I employed several methods of phylogenetic and DNA sequence analysis, along with comparisons to geological, biogeographic, and phylogeographic studies throughout the sampled regions. These analyses on Pogonomyrmex harvester ants reveal a complex pattern of vicariance and dispersal that is largely concordant with models of late Miocene, Pliocene, and Pleistocene range shifts among various arid-adapted taxa in North America.
ContributorsMott, Brendon (Author) / Gadau, Juergen (Thesis advisor) / Fewell, Jennifer (Committee member) / Anderson, Kirk (Committee member) / Arizona State University (Publisher)
Created2012
Description
Despite the minor differences in the inclusiveness of the word, there is a general assumption among the scientific community that the 'pursuit of knowledge' is the most fundamental element in defining the word 'science'. However, a closer examination of how science is being conducted in modern-day South Korea reveals a value system starkly different from the value of knowledge. By analyzing the political discourse of the South Korean policymakers, mass media, and government documents, this study examines the definition of science in South Korea. The analysis revealed that the Korean science, informed by the cultural, historical, and societal contexts, is largely focused on the values of national economic prosperity, international competitiveness, and international reputation of the country, overshadowing other values like the pursuit of knowledge or even individual rights. The identification of the new value system in South Korean science deviating from the traditional definition of science implies that there must be other definitions of science that also deviates, and that even in the Western world, the definition of science may yield similar deviations upon closer examination. The compatibility of the South Korean brand of science to the international scientific community also implies that a categorical quality is encompassing these different contextual definitions of science.
ContributorsHyun, Byunghun (Author) / Hurlbut, Ben (Thesis advisor) / Maienschein, Jane (Committee member) / Ellison, Karin (Committee member) / Arizona State University (Publisher)
Created2011
Description
Evolution is the foundation of biology, yet it remains controversial even among college biology students. Acceptance of evolution is important for students if we want them to incorporate evolution into their scientific thinking. However, students’ religious beliefs are a consistent barrier to their acceptance of evolution due to a perceived conflict between religion and evolution. Using pre-post instructional surveys of students in introductory college biology, Study 1 establishes instructional strategies that can be effective for reducing students' perceived conflict between religion and evolution. Through interviews and qualitative analyses, Study 2 documents how instructors teaching evolution at public universities may be resistant towards implementing strategies that can reduce students' perceived conflict, perhaps because of their own lack of religious beliefs and lack of training and awareness about students' conflict with evolution. Interviews with religious students in Study 3 reveals that religious college biology students can perceive their instructors as unfriendly towards religion which can negatively impact these students' perceived conflict between religion and evolution. Study 4 explores how instructors at Christian universities, who share the same Christian backgrounds as their students, do not struggle with implementing strategies that reduce students' perceived conflict between religion and evolution. Cumulatively, these studies reveal a need for a new instructional framework for evolution education that takes into account the religious cultural difference between instructors who are teaching evolution and students who are learning evolution. As such, a new instructional framework is then described, Religious Cultural Competence in Evolution Education (ReCCEE), that can help instructors teach evolution in a way that can reduce students' perceived conflict between religion and evolution, increase student acceptance of evolution, and create more inclusive college biology classrooms for religious students.
ContributorsBarnes, Maryann Elizabeth (Author) / Brownell, Sara (Thesis advisor) / Nesse, Randolph (Committee member) / Collins, James (Committee member) / Husman, Jenefer (Committee member) / Maienschein, Jane (Committee member) / Arizona State University (Publisher)
Created2018
Description
Persistent cooperation between unrelated conspecifics rarely occurs in mature eusocial insect societies. In this dissertation, I present evidence of non-kin cooperation in the Nearctic honey ant Myrmecocystus mendax. Using microsatellite markers, I show that mature colonies in the Sierra Ancha Mountain of central Arizona contain multiple unrelated matrilines, an observation that is consistent with primary polygyny. In contrast, similar analyses suggest that colonies in the Chiricahua Mountains of southeastern Arizona are primarily monogynous. These interpretations are consistent with field and laboratory observations. Whereas cooperative colony founding was observed frequently among groups of Sierra Ancha foundresses, founding in the Chiricahua population was restricted to individual foundresses. Furthermore, Sierra Ancha foundresses successfully established incipient laboratory colonies without undergoing queen culling following emergence of the first workers. Multi-queen laboratory Sierra Ancha colonies also produced more workers and repletes than haplometrotic colonies, and when brood raiding was induced between colonies, queens of those with more workers had a higher survival probability.
Microsatellite analyses of additional locations within the M. mendax range suggest that polygyny is also present in some other populations, especially in central-northern Arizona, albeit at lower frequencies than that in the Sierra Anchas. In addition, analyses of multiple types of genetic data, including microsatellites, the mitochondrial barcoding region, and over 2000 nuclear ultra-conserved elements indicate that M. mendax populations within the southwestern U.S. and northwestern Mexico are geographically structured, with strong support for the existence of two or more divergent clades as well as isolation-by-distance within clades. This structure is further shown to correlate with variation in queen number and hair length, a diagnostic taxonomic feature used to distinguish honey ant species.
Together, these findings suggest that regional ecological pressures (e.g. colony density , climate) may have acted on colony founding and social strategy to select for increasing workforce size and, along with genetic drift, have driven geographically isolated M. mendax populations to differentiate genetically and morphologically. The presence of colony fusion in the laboratory and life history traits in honey ant that are influenced by colony size, including repletism, brood raiding, and tournament, support this evolutionary scenario.
Microsatellite analyses of additional locations within the M. mendax range suggest that polygyny is also present in some other populations, especially in central-northern Arizona, albeit at lower frequencies than that in the Sierra Anchas. In addition, analyses of multiple types of genetic data, including microsatellites, the mitochondrial barcoding region, and over 2000 nuclear ultra-conserved elements indicate that M. mendax populations within the southwestern U.S. and northwestern Mexico are geographically structured, with strong support for the existence of two or more divergent clades as well as isolation-by-distance within clades. This structure is further shown to correlate with variation in queen number and hair length, a diagnostic taxonomic feature used to distinguish honey ant species.
Together, these findings suggest that regional ecological pressures (e.g. colony density , climate) may have acted on colony founding and social strategy to select for increasing workforce size and, along with genetic drift, have driven geographically isolated M. mendax populations to differentiate genetically and morphologically. The presence of colony fusion in the laboratory and life history traits in honey ant that are influenced by colony size, including repletism, brood raiding, and tournament, support this evolutionary scenario.
ContributorsEriksson, Ti (Author) / Gadau, Jürgen (Thesis advisor) / Taylor, Jay (Thesis advisor) / Fewell, Jennifer (Committee member) / Hӧlldobler, Bert (Committee member) / Johnson, Robert (Committee member) / Pratt, Stephen (Committee member) / Arizona State University (Publisher)
Created2018
Description
The most abundantly studied societies, with the exception of humans, are those of the eusocial insects, which include all ants. Eusocial insect societies are typically composed of many dozens to millions of individuals, referred to as nestmates, which require some form of communication to maintain colony cohesion and coordinate the activities within them. Nestmate recognition is the process of distinguishing between nestmates and non-nestmates, and embodies the first line of defense for social insect colonies. In ants, nestmate recognition is widely thought to occur through olfactory cues found on the exterior surfaces of individuals. These cues, called cuticular hydrocarbons (CHCs), comprise the overwhelming majority of ant nestmate profiles and help maintain colony identity. In this dissertation, I investigate how nestmate recognition is influenced by evolutionary, ontogenetic, and environmental factors. First, I contributed to the sequencing and description of three ant genomes including the red harvester ant, Pogonomyrmex barbatus, presented in detail here. Next, I studied how variation in nestmate cues may be shaped through evolution by comparatively studying a family of genes involved in fatty acid and hydrocarbon biosynthesis, i.e., the acyl-CoA desaturases, across seven ant species in comparison with other social and solitary insects. Then, I tested how genetic, developmental, and social factors influence CHC profile variation in P. barbatus, through a three-part study. (1) I conducted a descriptive, correlative study of desaturase gene expression and CHC variation in P. barbatus workers and queens; (2) I explored how larger-scale genetic variation in the P. barbatus species complex influences CHC variation across two genetically isolated lineages (J1/J2 genetic caste determining lineages); and (3) I experimentally examined how CHC development is influenced by an individual’s social environment. In the final part of my work, I resolved discrepancies between previous findings of nestmate recognition behavior in P. barbatus by studying how factors of territorial experience, i.e., spatiotemporal relationships, affect aggressive behaviors among red harvester ant colonies. Through this research, I was able to identify promising methodological approaches and candidate genes, which both broadens our understanding of P. barbatus nestmate recognition systems and supports future functional genetic studies of CHCs in ants.
ContributorsCash, Elizabeth I (Author) / Gadau, Jürgen (Thesis advisor) / Liebig, Jürgen (Thesis advisor) / Fewell, Jennifer (Committee member) / Hölldobler, Berthold (Committee member) / Kusumi, Kenro (Committee member) / Arizona State University (Publisher)
Created2016
Description
This thesis explores concept of "global bioethics" in both its development as well as its current state in an effort to understand exactly where it fits into the larger field of bioethics. Further, the analysis poses specific questions regarding what it may contribute to this field and related fields, and the possibility and scope associated with the continued development of global bioethics as its own discipline. To achieve this, the piece addresses questions regarding current opinions on the subject, the authorities and their associated publications related to global bioethics, and what the aims of the subject should be given its current state. "Global Bioethics" is a term that, while seen frequently in bioethics literature, is difficult to define succinctly. While many opinions are provided on the concept, little consensus exists regarding its application and possible contributions and, in some cases, even its very possibility. Applying ethical principles of health and medicine globally is undoubtedly complicated by the cultural, social, and geographical considerations associated with understanding health and medicine in different populations, leading to a dichotomy between two schools of thought in relation to global bioethics. These two sides consist of those who think that universality of bioethics is possible whereas the opposing viewpoint holds that relativism is the key to applying ethics on a global scale. Despite the aforementioned dichotomy in addressing applications of global bioethics, this analysis shows that the goals of the subject should be more focused on contributing to ethical frameworks and valuable types of thinking related to the ethics health and medicine on a global scale. This is achieved through an exploration of bioethics in general, health as a function of society and culture, the history and development of global bioethics itself, and an exploration of pertinent global health topics. While primarily descriptive in nature, this analysis critiques some of the current discussions and purported goals surrounding global bioethics, recommending that the field focus on fostering valuable discussion and framing of issues rather than the pursuit of concrete judgments on moral issues in global health and medicine.
ContributorsRuffenach, Stephen Charles (Author) / Robert, Jason S (Thesis advisor) / Maienschein, Jane (Committee member) / Hruschka, Daniel J (Committee member) / Arizona State University (Publisher)
Created2011
Climate Sensitivity in Mature Versus Pre-Reproductive Saguaro Determined from Spine Isotopic Signals
Description
The saguaro cactus is vital to the unique biodiversity of the Sonoran Desert. Many animals rely on it for survival and shelter. Due to its thick waxy exterior, it is able to retain a massive amount of water in its succulent stems, making it an ideal habitat for many birds that are native to the region. It also holds a large cultural significance for many native tribes of this region. Thus, it is important to understand how these magnificent plants are affected by changing environmental conditions in order to protect them in the future. Measurements of carbon isotope (13C) signals in saguaros spine tissues have been shown to be a robust approach for evaluating plant responses to climate variation over multiple seasons and years. This study investigated growth and 13C signals in young saguaros (< 2.5 m tall) at a location north of Phoenix to compare with large saguaros (> 4 m tall) that actively flower in the spring. Adolescent saguaros were examined to determine how they responded to variation in moisture between the years 2012 through 2016. As with a previous study by Hultine et al. (2018), this research demonstrated a strong relationship between height growth and precipitation. Stem growth was also highly correlated with the number of areoles produced across both young and old plants. Winter and late summer moisture from the previous year had a significant effect on stem growth, and a legacy effect could be seen in the low growth rates in 2014 which may be a result of low precipitation during the previous fall and winter. This study also established that the adolescent saguaro may be less sensitive to seasonal changes than the mature saguaro. When comparing the large plants with the adolescent plants, spine 13C values were similar between mature and adolescent plants, indicating that perhaps flower does not impose a significant added cost to saguaro water budgets. However, identifying the cost of flowering requires more investigation than that from only spine carbon isotope measurements and coarse measurements of plant productivity.
ContributorsDe Leon, Isabella (Author) / Hultine, Kevin (Thesis advisor) / Pigg, Kathleen (Thesis advisor) / Maienschein, Jane (Committee member) / Arizona State University (Publisher)
Created2021
Description
Dominance behavior can regulate a division of labor in a group, such as that between reproductive and non-reproductive individuals. Manipulations of insect societies in a controlled environment can reveal how dominance behavior is regulated. Here, I examined how morphological caste, fecundity, group size, and age influence the expression of dominance behavior using the ponerine ant Harpegnathos saltator. All H. saltator females have the ability to reproduce. Only those with a queen morphology that enables dispersal, however, show putative sex pheromones. In contrast, those with a worker morphology normally express dominance behavior. To evaluate how worker-like dominance behavior and associated traits could be expressed in queens, I removed the wings from alate gynes, those with a queen morphology who had not yet mated or left the nest, making them dealate. Compared to gynes with attached wings, dealates frequently performed dominance behavior. In addition, only the dealates demonstrated worker-like ovarian activity in the presence of reproductive individuals, whereas gynes with wings produced sex pheromones exclusively. Therefore, the attachment of wings determines a gyne’s expression of worker-like dominance behavior and physiology. When the queen dies, workers establish a reproductive hierarchy among themselves by performing a combination of dominance behaviors. To understand how reproductive status depends on these interactions as well as a worker’s age, I measured the frequency of dominance behaviors in groups of different size composed of young and old workers. The number of workers who expressed dominance scaled with the size of the group, but younger ones were more likely to express dominance behavior and eventually become reproductive. Therefore, the predisposition of age integrates with a self-organized process to form this reproductive hierarchy. A social insect’s fecundity and fertility signal depends on social context because fecundity increases with colony size. To evaluate how a socially dependent signal regulates dominance behavior, I manipulated a reproductive worker’s social context. Reproductive workers with reduced fecundity and a less prominent fertility signal expressed more dominance behavior than those with a stronger fertility signal and higher fecundity. Therefore, dominance behavior reinforces rank to compensate for a weak signal, indicating how social context can feed back to influence the maintenance of dominance. Mechanisms that regulate H. saltator’s reproductive hierarchy can inform how the reproductive division of labor is regulated in other groups of animals.
ContributorsPyenson, Benjamin (Author) / Liebig, Jürgen (Thesis advisor) / Hölldobler, Bert (Committee member) / Fewell, Jennifer (Committee member) / Pratt, Stephen (Committee member) / Kang, Yun (Committee member) / Arizona State University (Publisher)
Created2022