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- Genre: Masters Thesis
- Creators: Arizona State University
- Member of: ASU Electronic Theses and Dissertations
Description
Given the success of science, weak forms of mind-brain dependence are commonly treated as uncontroversial within contemporary philosophies of mind. More controversial are the different metaphysical claims inferred from this dependence, many ascribing ontological priority to the brain. Consider the following three propositions: (i) neurological events are essentially identified by their role in material systems, laws, and causes that are constitutively non-rational; (ii) at least some mental events are essentially identified in virtue of their role in the use of reason; (iii) all mental events are realized by, identical to, or composed out of, neurological events. (i) is uncontroversial. However, (iii) is strictly materialistic. (i), (ii) and (iii) taken together appear incoherent. A fruitful task for philosophy is to resolve this apparent incoherence. In his 1997 book The Last Word Thomas Nagel offers an explication of reason that conceptually transcends the nature of material substrate. In his 2010 article "Modest Dualism" Tyler Burge offers reasons to think of propositional thought as irreducible to the concepts of the material sciences. Both focus on rationality as a unique form of intentionality. Both philosophers also reject materialism (iii). On their accounts it's reasonable to take 'rational intentionality' as exhibiting a logical priority of the mind with respect to the brain in inquiries into the nature of mind. Granting this, the diminished conception of mind presupposed by prevailing contemporary theories is seen to be the result of a more general failure to recognize the logical priority and intricate nature of rationality. The robust views of rationality expressed by Nagel and Burge constitute grounds for argument against even the weakest form of materialism. I develop such an argument in this thesis, showing that the propositional attitudes exhibited in thought and speech preclude all materialistic notions of mind. Furthermore, I take the nature of propositional attitudes to suggest a perspective for exploring the fundamental nature of mind, one that focuses not on composition but on rational powers.
ContributorsGoodrich, Gregory (Author) / Kobes, Bernard W (Thesis advisor) / White, Michael J. (Committee member) / Anderson, Owen (Committee member) / Arizona State University (Publisher)
Created2011
Description
ABSTRACT 1. Aposematic signals advertise prey distastefulness or metabolic unprofitability to potential predators and have evolved independently in many prey groups over the course of evolutionary history as a means of protection from predation. Most aposematic signals investigated to date exhibit highly chromatic patterning; however, relatives in these toxic groups with patterns of very low chroma have been largely overlooked. 2. We propose that bright displays with low chroma arose in toxic prey species because they were more effective at deterring predation than were their chromatic counterparts, especially when viewed in relatively low light environments such as forest understories. 3. We analyzed the reflectance and radiance of color patches on the wings of 90 tropical butterfly species that belong to groups with documented toxicity that vary in their habitat preferences to test this prediction: Warning signal chroma and perceived chromaticity are expected to be higher and brightness lower in species that fly in open environments when compared to those that fly in forested environments. 4. Analyses of the reflectance and radiance of warning color patches and predator visual modeling support this prediction. Moreover, phylogenetic tests, which correct for statistical non-independence due to phylogenetic relatedness of test species, also support the hypothesis of an evolutionary correlation between perceived chromaticity of aposematic signals and the flight habits of the butterflies that exhibit these signals.
ContributorsDouglas, Jonathan Marion (Author) / Rutowski, Ronald L (Thesis advisor) / Gadau, Juergen (Committee member) / McGraw, Kevin J. (Committee member) / Arizona State University (Publisher)
Created2013
Description
Gene-centric theories of evolution by natural selection have been popularized and remain generally accepted in both scientific and public paradigms. While gene-centrism is certainly parsimonious, its explanations fall short of describing two patterns of evolutionary and social phenomena: the evolution of sex and the evolution of social altruism. I review and analyze current theories on the evolution of sex. I then introduce the conflict presented to gene-centric evolution by social phenomena such as altruism and caste sterility in eusocial insects. I review gene-centric models of inclusive fitness and kin selection proposed by Hamilton and Maynard Smith. Based their assumptions, that relatedness should be equal between sterile workers and reproductives, I present several empirical examples that conflict with their models. Following that, I introduce a unique system of genetic caste determination (GCD) observed in hybrid populations of two sister-species of seed harvester ants, Pogonomyrmex rugosus and Pogonomyrmex barbatus. I review the evidence for GCD in those species, followed by a critique of the current gene-centric models used to explain it. In chapter two I present my own theoretical model that is both simple and extricable in nature to explain the origin, evolution, and maintenance of GCD in Pogonomyrmex. Furthermore, I use that model to fill in the gaps left behind by the contributing authors of the other GCD models. As both populations in my study system formed from inter-specific hybridization, I review modern discussions of heterosis (also called hybrid vigor) and use those to help explain the ecological competitiveness of GCD. I empirically address the inbreeding depression the lineages of GCD must overcome in order to remain ecologically stable, demonstrating that as a result of their unique system of caste determination, GCD lineages have elevated recombination frequencies. I summarize and conclude with an argument for why GCD evolved under selective mechanisms which cannot be considered gene-centric, providing evidence that natural selection can effectively operate on non-heritable genotypes appearing in groups and other social contexts.
ContributorsJacobson, Neal (Author) / Gadau, Juergen (Thesis advisor) / Laubichler, Manfred (Committee member) / Pratt, Stephen (Committee member) / Arizona State University (Publisher)
Created2012
Description
Infectious diseases have been a major threat to survival throughout human history. Humans have developed a behavioral immune system to prevent infection by causing individuals to avoid people, food, and objects that could be contaminated. This current project investigates how ambient temperature affects the activation of this system. Because temperature is positively correlated with the prevalence of many deadly diseases, I predict that temperature moderates the behavioral immune system, such that a disease prime will have a stronger effect in a hot environment compared to a neutral environment and one's avoidant behaviors will be more extreme. Participants were placed in a hot room (M = 85F) or a neutral room (M = 77F) and shown a disease prime slide show or a neutral slide show. Disgust sensitivity and perceived vulnerability surveys were used to measure an increased perceived risk to disease. A taste test between a disgusting food item (gummy bugs) and a neutral food item (gummy animals) measured food avoidance. There was no significant avoidance of the gummy and no significant difference in ratings of disgust sensitivity or perceived vulnerability as a function of temperature conditions. There were no significant interactions between temperature and disease. The conclusion is that this study did not provide evidence that temperature moderates the effect of disease cues on behavior.
ContributorsOsborne, Elizabeth (Author) / Cohen, Adam B. (Thesis advisor) / Kwan, Sau (Committee member) / Neuberg, Steven (Committee member) / Arizona State University (Publisher)
Created2012
Description
Proper regulation of the Transforming Growth Factor-beta (TGF-b) pathway is important for maintaining homeostasis and development in various tissues across vertebrates and invertebrates. When TGF-b pathway signaling is disrupted it leads to tumor growth, birth defects, and other diseases. The identification and study of the various regulatory methods utilized within TGF-b pathway signaling is important to aid the understanding of disease prognosis and prevention. In the TGF-b pathway in Drosophila, dCORL functions in the dActivin subpathway and acts as a regulator of dSmad2 in the larval brain. dCORL is encoded by a gene on the fourth chromosome, in Drosophila. To learn more about dCORL’s role in the pathway, two fourth chromosomes were created that allow clonal analysis to be conducted. Clonal analysis is needed to determine dCORL’s role in TGF-b regulation in the adult brain. In my first project, both chromosomes were successfully created. Though, the importance of understanding regulatory mechanisms goes past one protein. In my second project, multiple conserved prodomain cysteines were identified in human amino acid alignments of 33 TGF-b family proteins across the three TGF-b subfamilies. Database mining identified conserved prodomain cysteine mutations in 10 proteins and their mutant phenotypes. Common phenotypes for conserved cysteine mutations suggest new heterodimer pairs. The most frequent mutant phenotypes associated with new heterodimers were tumors. Conserved prodomain cysteine mutations were connected to cysteine mutations in known regulatory partner proteins by mutant phenotype, yielding numerous new regulatory interactions. The most frequent mutant phenotypes connecting new regulatory interactions between TGF-b proteins and regulatory partners proteins were tumors. Together, my projects expand knowledge of regulatory mechanisms within the TGF-b pathway in Drosophila and humans, while providing hypotheses for further investigation.
ContributorsDaly, Samantha M. (Author) / Newfeld, Stuart J. (Thesis advisor) / Capco, David G. (Committee member) / Ugarova, Tatiana P. (Committee member) / Arizona State University (Publisher)
Created2022
Description
Insecticide resistance is a continuing issue that negatively affects both public health and agriculture and allows vector-borne diseases to spread throughout the globe. To improve resistance management strategies (RMS), robust susceptibility bioassays need to be performed in order to fill the gap of the relationship between resistant and susceptible genotype and phenotype, and a deeper knowledge of how bioassay data relates to vector control success or failure is imperative. A bioassay method that is infrequently used but yields robust results is the topical application bioassay, where the insect is directly treated with a constant volume and concentration of an insecticide via a syringe. To bring more attention to this method, my colleagues and I published a paper in the Journal of Visualized Experiments where the optimized protocol of the topical application bioassay for mosquitoes and fruit flies is described, and the strengths and limitations to the method are explained. To further investigate insecticide susceptibility tests, I set up my individual project where I used Aedes aegypti mosquitoes to compare the topical application bioassay to the commonly used Centers for Disease Control and Prevention (CDC) bottle bioassay and World Health Organization (WHO) tube test. The objective of this study was to test which method exhibited the most variability in mortality results, which would guide the choice of assay to determine the link between resistant and susceptible genotype and phenotype. The results showed that the topical application method did indeed exhibit the least amount of variation, followed by the CDC bottle bioassay (WHO data is currently being collected). This suggests that the topical application bioassay could be a useful tool in insecticide resistance surveillance studies, and, depending on the goal, may be better than the CDC and WHO tube tests for assessing resistance levels at a given site. This study challenges the value of the widely used CDC and WHO assays and provides a discussion on the importance of technical and practical resistance assays. This will help vector control specialists to collect accurate surveillance data that will inform effective RMS.
ContributorsAlthoff, Rachel (Author) / Huijben, Silvie (Thesis advisor) / Harris, Robin (Committee member) / Collins, James (Committee member) / Arizona State University (Publisher)
Created2022
Description
This review aims to provide a comprehensive review of the most recent literature on adaptive therapy, a promising new approach to cancer treatment that leverages evolutionary theory to prolong tumor control1. By capitalizing on the competition between drug-sensitive and drug-resistant cells, adaptive therapy has led to a paradigm shift in oncology. Through mathematical and in silico models, researchers have examined key factors such as dose timing, cost of resistance, and spatial dynamics in tumor response to adaptive therapy. With a partial focus on preclinical experiments involving ovarian and breast cancer, this review will discuss the demonstrated effectiveness of adaptive therapy in improving progression free survival and tumor control. Through the review process, it was determined that dose modulation outperformed drug-vacation strategies, emphasizing the significance of tumor heterogeneity and spatial structure in accurately modeling adaptive therapy mechanisms. The potential of ongoing clinical trials to improve patient outcomes and long-term treatment efficacy is emphasized, while a thorough analysis of study methodologies shapes the future direction of adaptive therapy research.
ContributorsRichker, Harley (Author) / Maley, Carlo C (Thesis advisor) / Compton, Carolyn (Committee member) / Wilson, Melisaa (Committee member) / Arizona State University (Publisher)
Created2023
Description
An ancient endosymbiosis involving early eukaryotic cells and cyanobacteriaresulted in the modern chloroplast organelle of the Archaeplastida clade, including all land plants. Throughout chloroplast evolution, many genes from the chloroplast genome were transferred to the nuclear genome, including the genetic pathway for synthesis of the bacterial polymer peptidoglycan (PG). In the ~1 billion years since the acquisition of the chloroplast, seed plants can now be grouped into species that retain ten PG genes (“full-PG”) or only four of the ten (“4-PG”). In Arabidopsis thaliana, a 4-PG flowering plant, knockout mutants for the PG gene murE show a proplastid phenotype, where chloroplast development is completely halted. In this report, A. thaliana mutants for the remaining three PG genes (mraY, murG, and ddl) were phenotyped to test for their functions.
Two T-DNA insertion lines for each gene were selected from the Arabidopsis Biological Resource Center, and either confirmed as homozygotes or selfed to produce homozygous lines. These lines were then grown for at least two generations to confirm homozygous status and the location of the T-DNA insertion was identified using Sanger sequencing. All mutant lines had an insertion in either an exon or 5’ UTR of target genes. All lines were then grown on soil in conjunction with wild type plants for comparison of germination, morphology, and transcriptomics. No differences were observed in time to germination or morphology compared to the wild type control. Transcriptomics showed that target PG genes were differentially expressed in each line, but usually at a non-significant value. Genes related to flowering and reproduction were significantly differentially expressed in the mraY lines.
Protoplasts were produced to image chloroplasts and identify any morphological or developmental effects. Chloroplast morphology was comparable to wild type; additionally, measurements of photosynthetic efficiency were not found to be significantly different than wild type. Together these data show that A. thaliana mutants for three PG genes do not display a phenotype like those for mutants of the fourth gene, murE. The results suggest that PG genes in A. thaliana are no longer linked to PG production and have diverged from the ancestral bacterial pathway.
ContributorsTemnyk, Stephanie (Author) / McCutcheon, John (Thesis advisor) / Mazor, Yuval (Committee member) / Chen, Changbin (Committee member) / Arizona State University (Publisher)
Created2024
Description
Teaching evolution has been shown to be a challenge for faculty, in both K-12 and postsecondary education. Many of these challenges stem from perceived conflicts not only between religion and evolution, but also faculty beliefs about religion, it's compatibility with evolutionary theory, and it's proper role in classroom curriculum. Studies suggest that if educators engage with students' religious beliefs and identity, this may help students have positive attitudes towards evolution. The aim of this study was to reveal attitudes and beliefs professors have about addressing religion and providing religious scientist role models to students when teaching evolution. 15 semi-structured interviews of tenured biology professors were conducted at a large Midwestern universiy regarding their beliefs, experiences, and strategies teaching evolution and particularly, their willingness to address religion in a class section on evolution. Following a qualitative analysis of transcripts, professors did not agree on whether or not it is their job to help students accept evolution (although the majority said it is not), nor did they agree on a definition of "acceptance of evolution". Professors are willing to engage in students' religious beliefs, if this would help their students accept evolution. Finally, professors perceived many challenges to engaging students' religious beliefs in a science classroom such as the appropriateness of the material for a science class, large class sizes, and time constraints. Given the results of this study, the author concludes that instructors must come to a consensus about their goals as biology educators as well as what "acceptance of evolution" means, before they can realistically apply the engagement of student's religious beliefs and identity as an educational strategy.
ContributorsBarnes, Maryann Elizabeth (Author) / Brownell, Sara E (Thesis advisor) / Brem, Sarah K. (Thesis advisor) / Lynch, John M. (Committee member) / Ellison, Karin (Committee member) / Arizona State University (Publisher)
Created2014
Description
Regulation of transcription initiation is a critical factor in the emergence of diverse biological phenotypes, including the development of multiple cell types from a single genotype, the ability of organisms to respond to environmental cues, and the rise of heritable diseases. Transcription initiation is regulated in large part by promoter regions of DNA. The identification and characterization of cis-regulatory regions, and understanding how these sequences differ across species, is a question of interest in evolution. To address this topic, I used the model organism Daphnia pulex, a well-characterized microcrustacean with an annotated genome sequence and selected a distribution of well-defined populations geographically located throughout the Midwestern US, Oregon, and Canada. Using isolated total RNA from adult, female Daphnia originating from the selected populations as well as a related taxon, Daphnia pulicaria (200,000 years diverged from D. pulex), I identified an average of over 14,000 (n=14,471) promoter regions using a novel transcription start site (TSS) profiling method, STRIPE-seq. Through the identification of sequence architecture, promoter class, conservation, and transcription start region (TSR) width, of cis-regulatory regions across the aforementioned Daphnia populations, I constructed a system for the study of promoter evolution, enabling a robust interpretation of promoter evolution in the context of the population-genetic environment. The methodology presented, coupled with the generated dataset, provides a foundation for the study of the evolution of promoters across both species and populations.
ContributorsSnyder, Shannon (Author) / Lynch, Michael (Thesis advisor) / Harris, Robin (Committee member) / Raborn, Randolph T (Committee member) / Wideman, Jeremy (Committee member) / Arizona State University (Publisher)
Created2020