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
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
Urbanization provides an excellent opportunity to examine the effects of human-induced rapid environmental change (HIREC) on natural ecosystems. Certain species can dominate in urban habitats at the expense of biodiversity. Phenotypic plasticity may be the mechanism by which these 'urban exploiters' flourish in urban areas. Color displays and condition-dependent phenotypes are known to be highly plastic. However, conspicuous color displays are perplexing in that they can be costly to produce and may increase detection by enemies. The Western black widow spider () is a superabundant pest species that forms dense aggregations throughout metropolitan Phoenix, Arizona, USA. Adult female display a red hourglass on their abdomen, which is speculated to function as a conspicuous warning signal to enemies. Here, I performed field studies to identify how widow morphology and hourglass color differ between urban and desert subpopulations. I also conducted laboratory experiments to examine the dietary sensitivity of hourglass coloration and to identify its functional role in the contexts of agonism, mating, and predator defense. My field data reveal significant spatial variation across urban and desert subpopulations in ecology and color. Furthermore, hourglass coloration was significantly influenced by environmental factors unique to urban habitats. Desert spiders were found to be smaller and less colorful than urban spiders. Throughout, I observed a positive correlation between body condition and hourglass size. Laboratory diet manipulations empirically confirm the condition-dependence of hourglass size. Additionally, widows with extreme body conditions exhibited condition-dependent coloration. However, hourglass obstruction and enlargement did not produce any effects on the outcome of agonistic encounters, male courtship, or predator deterrence. This work offers important insights into the effects of urbanization on the ecology and coloration of a superabundant pest species. While the function of the hourglass remains undetermined, my findings characterize the black widow's hourglass as extremely plastic. Plastic responses to novel environmental conditions can modify the targets of natural selection and subsequently influence evolutionary outcomes. Therefore, assuming a heritable component to this plasticity, the response of hourglass plasticity to the abrupt environmental changes in urban habitats may result in the rapid evolution of this phenotype.
ContributorsGburek, Theresa (Author) / Johnson, James C. (Thesis advisor) / McGraw, Kevin J. (Committee member) / Rutowski, Ronald L (Committee member) / Arizona State University (Publisher)
Created2014
Description
The phycologist, M. R. Droop, studied vitamin B12 limitation in the flagellate Monochrysis lutheri and concluded that its specific growth rate depended on the concentration of the vitamin within the cell; i.e. the cell quota of the vitamin B12. The Droop model provides a mathematical expression to link growth rate to the intracellular concentration of a limiting nutrient. Although the Droop model has been an important modeling tool in ecology, it has only recently been applied to study cancer biology. Cancer cells live in an ecological setting, interacting and competing with normal and other cancerous cells for nutrients and space, and evolving and adapting to their environment. Here, the Droop equation is used to model three cancers.
First, prostate cancer is modeled, where androgen is considered the limiting nutrient since most tumors depend on androgen for proliferation and survival. The model's accuracy for predicting the biomarker for patients on intermittent androgen deprivation therapy is tested by comparing the simulation results to clinical data as well as to an existing simpler model. The results suggest that a simpler model may be more beneficial for a predictive use, although further research is needed in this field prior to implementing mathematical models as a predictive method in a clinical setting.
Next, two chronic myeloid leukemia models are compared that consider Imatinib treatment, a drug that inhibits the constitutively active tyrosine kinase BCR-ABL. Both models describe the competition of leukemic and normal cells, however the first model also describes intracellular dynamics by considering BCR-ABL as the limiting nutrient. Using clinical data, the differences in estimated parameters between the models and the capacity for each model to predict drug resistance are analyzed.
Last, a simple model is presented that considers ovarian tumor growth and tumor induced angiogenesis, subject to on and off anti-angiogenesis treatment. In this environment, the cell quota represents the intracellular concentration of necessary nutrients provided through blood supply. Mathematical analysis of the model is presented and model simulation results are compared to pre-clinical data. This simple model is able to fit both on- and off-treatment data using the same biologically relevant parameters.
First, prostate cancer is modeled, where androgen is considered the limiting nutrient since most tumors depend on androgen for proliferation and survival. The model's accuracy for predicting the biomarker for patients on intermittent androgen deprivation therapy is tested by comparing the simulation results to clinical data as well as to an existing simpler model. The results suggest that a simpler model may be more beneficial for a predictive use, although further research is needed in this field prior to implementing mathematical models as a predictive method in a clinical setting.
Next, two chronic myeloid leukemia models are compared that consider Imatinib treatment, a drug that inhibits the constitutively active tyrosine kinase BCR-ABL. Both models describe the competition of leukemic and normal cells, however the first model also describes intracellular dynamics by considering BCR-ABL as the limiting nutrient. Using clinical data, the differences in estimated parameters between the models and the capacity for each model to predict drug resistance are analyzed.
Last, a simple model is presented that considers ovarian tumor growth and tumor induced angiogenesis, subject to on and off anti-angiogenesis treatment. In this environment, the cell quota represents the intracellular concentration of necessary nutrients provided through blood supply. Mathematical analysis of the model is presented and model simulation results are compared to pre-clinical data. This simple model is able to fit both on- and off-treatment data using the same biologically relevant parameters.
ContributorsEverett, Rebecca Anne (Author) / Kuang, Yang (Thesis advisor) / Nagy, John (Committee member) / Milner, Fabio (Committee member) / Crook, Sharon (Committee member) / Jackiewicz, Zdzislaw (Committee member) / Arizona State University (Publisher)
Created2015
Description
In 1968, phycologist M.R. Droop published his famous discovery on the functional relationship between growth rate and internal nutrient status of algae in chemostat culture. The simple notion that growth is directly dependent on intracellular nutrient concentration is useful for understanding the dynamics in many ecological systems. The cell quota in particular lends itself to ecological stoichiometry, which is a powerful framework for mathematical ecology. Three models are developed based on the cell quota principal in order to demonstrate its applications beyond chemostat culture.
First, a data-driven model is derived for neutral lipid synthesis in green microalgae with respect to nitrogen limitation. This model synthesizes several established frameworks in phycology and ecological stoichiometry. The model demonstrates how the cell quota is a useful abstraction for understanding the metabolic shift to neutral lipid production that is observed in certain oleaginous species.
Next a producer-grazer model is developed based on the cell quota model and nutrient recycling. The model incorporates a novel feedback loop to account for animal toxicity due to accumulation of nitrogen waste. The model exhibits rich, complex dynamics which leave several open mathematical questions.
Lastly, disease dynamics in vivo are in many ways analogous to those of an ecosystem, giving natural extensions of the cell quota concept to disease modeling. Prostate cancer can be modeled within this framework, with androgen the limiting nutrient and the prostate and cancer cells as competing species. Here the cell quota model provides a useful abstraction for the dependence of cellular proliferation and apoptosis on androgen and the androgen receptor. Androgen ablation therapy is often used for patients in biochemical recurrence or late-stage disease progression and is in general initially effective. However, for many patients the cancer eventually develops resistance months to years after treatment begins. Understanding how and predicting when hormone therapy facilitates evolution of resistant phenotypes has immediate implications for treatment. Cell quota models for prostate cancer can be useful tools for this purpose and motivate applications to other diseases.
First, a data-driven model is derived for neutral lipid synthesis in green microalgae with respect to nitrogen limitation. This model synthesizes several established frameworks in phycology and ecological stoichiometry. The model demonstrates how the cell quota is a useful abstraction for understanding the metabolic shift to neutral lipid production that is observed in certain oleaginous species.
Next a producer-grazer model is developed based on the cell quota model and nutrient recycling. The model incorporates a novel feedback loop to account for animal toxicity due to accumulation of nitrogen waste. The model exhibits rich, complex dynamics which leave several open mathematical questions.
Lastly, disease dynamics in vivo are in many ways analogous to those of an ecosystem, giving natural extensions of the cell quota concept to disease modeling. Prostate cancer can be modeled within this framework, with androgen the limiting nutrient and the prostate and cancer cells as competing species. Here the cell quota model provides a useful abstraction for the dependence of cellular proliferation and apoptosis on androgen and the androgen receptor. Androgen ablation therapy is often used for patients in biochemical recurrence or late-stage disease progression and is in general initially effective. However, for many patients the cancer eventually develops resistance months to years after treatment begins. Understanding how and predicting when hormone therapy facilitates evolution of resistant phenotypes has immediate implications for treatment. Cell quota models for prostate cancer can be useful tools for this purpose and motivate applications to other diseases.
ContributorsPacker, Aaron (Author) / Kuang, Yang (Thesis advisor) / Nagy, John (Committee member) / Smith, Hal (Committee member) / Kostelich, Eric (Committee member) / Kang, Yun (Committee member) / Arizona State University (Publisher)
Created2014
Description
There is increasing evidence that ovarian status influcences behavioral phenotype in workers of the honey bee Apis mellifera. Honey bee workers demonstrate a complex division of labor. Young workers perform in-hive tasks (e.g. brood care), while older bees perform outside tasks (e.g. foraging for food). This age correlated division of labor is known as temporal polyethism. Foragers demonstrate further division of labor with some bees biasing collection towards protein (pollen) and others towards carbohydrates (nectar). The Reproductive Ground-plan Hypothesis proposes that the ovary plays a regulatory role in foraging division of labor. European honey bee workers that have been selectively bred to store larger amounts of pollen (High strain) also have a higher number of ovarioles per ovary than workers from strains bred to store less pollen (Low strain). High strain bees also initiate foraging earlier than Low strain bees. The relationship between ovariole number and foraging behavior is also observed in wild-type Apis mellifera and Apis cerana: pollen-biased foragers have more ovarioles than nectar-biased foragers. In my first study, I investigated the pre-foraging behavioral patterns of the High and Low strain bees. I found that High strain bees progress through the temporal polyethism at a faster rate than Low strain bees. To ensure that the observed relationship between the ovary and foraging bias is not due to associated separate genes for ovary size and foraging behavior, I investigated foraging behavior of African-European backcross bees. The backcross breeding program was designed to break potential gene associations. The results from this study demonstrated the relationship between the ovary and foraging behavior, supporting the proposed causal linkage between reproductive development and behavioral phenotype. The final study was designed to elucidate a regulatory mechanism that links ovariole number with sucrose sensitivity, and loading decisions. I measured ovariole number, sucrose sensitivity and sucrose solution load size using a rate-controlled sucrose delivery system. I found an interaction effect between ovariole number and sucrose sensitivity for sucrose solution load size. This suggests that the ovary impacts carbohydrate collection through modulation of sucrose sensitivity. Because nectar and pollen collection are not independent, this would also impact protein collection.
ContributorsSiegel, Adam J (Author) / Page, Jr., Robert E (Thesis advisor) / Hamilton, Andrew L. (Committee member) / Brent, Colin S (Committee member) / Amdam, Gro V (Committee member) / McGraw, Kevin J. (Committee member) / Arizona State University (Publisher)
Created2011
Description
Sexual and social signals have long been thought to play an important role in speciation and diversity; hence, investigations of intraspecific communication may lead to important insights regarding key processes of evolution. Though we have learned much about the control, function, and evolution of animal communication by studying several very common signal types, investigating rare classes of signals may provide new information about how and why animals communicate. My dissertation research focused on rapid physiological color change, a rare signal-type used by relatively few taxa. To answer longstanding questions about this rare class of signals, I employed novel methods to measure rapid color change signals of male veiled chameleons Chamaeleo calyptratus in real-time as seen by the intended conspecific receivers, as well as the associated behaviors of signalers and receivers. In the context of agonistic male-male interactions, I found that the brightness achieved by individual males and the speed of color change were the best predictors of aggression and fighting ability. Conversely, I found that rapid skin darkening serves as a signal of submission for male chameleons, reducing aggression from winners when displayed by losers. Additionally, my research revealed that the timing of maximum skin brightness and speed of brightening were the best predictors of maximum bite force and circulating testosterone levels, respectively. Together, these results indicated that different aspects of color change can communicate information about contest strategy, physiology, and performance ability. Lastly, when I experimentally manipulated the external appearance of chameleons, I found that "dishonestly" signaling individuals (i.e. those whose behavior did not match their manipulated color) received higher aggression from unpainted opponents. The increased aggression received by dishonest signalers suggests that social costs play an important role in maintaining the honesty of rapid color change signals in veiled chameleons. Though the color change abilities of chameleons have interested humans since the time of Aristotle, little was previously known about the signal content of such changes. Documenting the behavioral contexts and information content of these signals has provided an important first step in understanding the current function, underlying control mechanisms, and evolutionary origins of this rare signal type.
ContributorsLigon, Russell (Author) / McGraw, Kevin J. (Committee member) / DeNardo, Dale F (Committee member) / Karsten, Kristopher B (Committee member) / Rutowski, Ronald L (Committee member) / Deviche, Pierre (Committee member) / Arizona State University (Publisher)
Created2015
Description
Predicting resistant prostate cancer is critical for lowering medical costs and improving the quality of life of advanced prostate cancer patients. I formulate, compare, and analyze two mathematical models that aim to forecast future levels of prostate-specific antigen (PSA). I accomplish these tasks by employing clinical data of locally advanced prostate cancer patients undergoing androgen deprivation therapy (ADT). I demonstrate that the inverse problem of parameter estimation might be too complicated and simply relying on data fitting can give incorrect conclusions, since there is a large error in parameter values estimated and parameters might be unidentifiable. I provide confidence intervals to give estimate forecasts using data assimilation via an ensemble Kalman Filter. Using the ensemble Kalman Filter, I perform dual estimation of parameters and state variables to test the prediction accuracy of the models. Finally, I present a novel model with time delay and a delay-dependent parameter. I provide a geometric stability result to study the behavior of this model and show that the inclusion of time delay may improve the accuracy of predictions. Also, I demonstrate with clinical data that the inclusion of the delay-dependent parameter facilitates the identification and estimation of parameters.
ContributorsBaez, Javier (Author) / Kuang, Yang (Thesis advisor) / Kostelich, Eric (Committee member) / Crook, Sharon (Committee member) / Gardner, Carl (Committee member) / Nagy, John (Committee member) / Arizona State University (Publisher)
Created2017