Matching Items (904)
Filtering by

Clear all filters

150916-Thumbnail Image.png
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

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
150622-Thumbnail Image.png
Description
A notable feature of advanced eusocial insect groups is a division of labor within the sterile worker caste. However, the physiological aspects underlying the differentiation of behavioral phenotypes are poorly understood in one of the most successful social taxa, the ants. By starting to understand the foundations on which social

A notable feature of advanced eusocial insect groups is a division of labor within the sterile worker caste. However, the physiological aspects underlying the differentiation of behavioral phenotypes are poorly understood in one of the most successful social taxa, the ants. By starting to understand the foundations on which social behaviors are built, it also becomes possible to better evaluate hypothetical explanations regarding the mechanisms behind the evolution of insect eusociality, such as the argument that the reproductive regulatory infrastructure of solitary ancestors was co-opted and modified to produce distinct castes. This dissertation provides new information regarding the internal factors that could underlie the division of labor observed in both founding queens and workers of Pogonomyrmex californicus ants, and shows that changes in task performance are correlated with differences in reproductive physiology in both castes. In queens and workers, foraging behavior is linked to elevated levels of the reproductively-associated juvenile hormone (JH), and, in workers, this behavioral change is accompanied by depressed levels of ecdysteroid hormones. In both castes, the transition to foraging is also associated with reduced ovarian activity. Further investigation shows that queens remain behaviorally plastic, even after worker emergence, but the association between JH and behavioral bias remains the same, suggesting that this hormone is an important component of behavioral development in these ants. In addition to these reproductive factors, treatment with an inhibitor of the nutrient-sensing pathway Target of Rapamycin (TOR) also causes queens to become biased towards foraging, suggesting an additional sensory component that could play an important role in division of labor. Overall, this work provides novel identification of the possible regulators behind ant division of labor, and suggests how reproductive physiology could play an important role in the evolution and regulation of non-reproductive social behaviors.
ContributorsDolezal, Adam G (Author) / Amdam, Gro V (Thesis advisor) / Brent, Colin S. (Committee member) / Gadau, Juergen (Committee member) / Hoelldobler, Bert (Committee member) / Liebig, Juergen (Committee member) / Arizona State University (Publisher)
Created2012
150818-Thumbnail Image.png
Description
While exercising mammalian muscle increasingly relies on carbohydrates for fuel as aerobic exercise intensity rises above the moderate range, flying birds are extraordinary endurance athletes and fuel flight, a moderate-high intensity exercise, almost exclusively with lipid. In addition, Aves have long lifespans compared to weight-matched mammals. As skeletal muscle mitochondria

While exercising mammalian muscle increasingly relies on carbohydrates for fuel as aerobic exercise intensity rises above the moderate range, flying birds are extraordinary endurance athletes and fuel flight, a moderate-high intensity exercise, almost exclusively with lipid. In addition, Aves have long lifespans compared to weight-matched mammals. As skeletal muscle mitochondria account for the majority of oxygen consumption during aerobic exercise, the primary goal was to investigate differences in isolated muscle mitochondria between these species and to examine to what extent factors intrinsic to mitochondria may account for the behavior observed in the intact tissue and whole organism. First, maximal enzyme activities were assessed in sparrow and rat mitochondria. Citrate synthase and aspartate aminotransferase activity were higher in sparrow compared to rat mitochondria, while glutamate dehydrogenase activity was lower. Sparrow mitochondrial NAD-linked isocitrate dehydrogenase activity was dependent on phosphate, unlike the mammalian enzyme. Next, the rate of oxygen consumption (JO), electron transport chain (ETC) activity, and reactive oxygen species (ROS) production were assessed in intact mitochondria. Maximal rates of fat oxidation were lower than for carbohydrate in rat but not sparrow mitochondria. ETC activity was higher in sparrows, but no differences were found in ROS production between species. Finally, fuel selection and control of respiration at three rates between rest and maximum were assessed. Mitochondrial fuel oxidation and selection mirrored that of the whole body; in rat mitochondria the reliance on carbohydrate increased as the rate of oxygen consumption increased, whereas fat dominated under all conditions in the sparrow. These data indicate fuel selection, at least in part, can be modulated at the level of the mitochondrial matrix when multiple substrates are present at saturating levels. As an increase in matrix oxidation-reduction potential has been linked to a suppression of fat oxidation and high ROS production, the high ETC activity relative to dehydrogenase activity in avian compared to mammalian mitochondria may result in lower matrix oxidation-reduction potential, allowing fatty acid oxidation to proceed while also resulting in low ROS production in vivo.
ContributorsKuzmiak, Sarah (Author) / Willis, Wayne T (Thesis advisor) / Mandarino, Lawrence (Committee member) / Sweazea, Karen (Committee member) / Harrison, Jon (Committee member) / Gadau, Juergen (Committee member) / Arizona State University (Publisher)
Created2012
151184-Thumbnail Image.png
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

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
151272-Thumbnail Image.png
Description
In social insect colonies, as with individual animals, the rates of biological processes scale with body size. The remarkable explanatory power of metabolic allometry in ecology and evolutionary biology derives from the great diversity of life exhibiting a nonlinear scaling pattern in which metabolic rates are not proportional to mass,

In social insect colonies, as with individual animals, the rates of biological processes scale with body size. The remarkable explanatory power of metabolic allometry in ecology and evolutionary biology derives from the great diversity of life exhibiting a nonlinear scaling pattern in which metabolic rates are not proportional to mass, but rather exhibit a hypometric relationship with body size. While one theory suggests that the supply of energy is a major physiological constraint, an alternative theory is that the demand for energy is regulated by behavior. The central hypothesis of this dissertation research is that increases in colony size reduce the proportion of individuals actively engaged in colony labor with consequences for energetic scaling at the whole-colony level of biological organization. A combination of methods from comparative physiology and animal behavior were developed to investigate scaling relationships in laboratory-reared colonies of the seed-harvester ant, Pogonomyrmex californicus. To determine metabolic rates, flow-through respirometry made it possible to directly measure the carbon dioxide production and oxygen consumption of whole colonies. By recording video of colony behavior, for which ants were individually paint-marked for identification, it was possible to reconstruct the communication networks through which information is transmitted throughout the colony. Whole colonies of P. californicus were found to exhibit a robust hypometric allometry in which mass-specific metabolic rates decrease with increasing colony size. The distribution of walking speeds also scaled with colony size so that larger colonies were composed of relatively more inactive ants than smaller colonies. If colonies were broken into random collections of workers, metabolic rates scaled isometrically, but when entire colonies were reduced in size while retaining functionality (queens, juveniles, workers), they continued to exhibit a metabolic hypometry. The communication networks in P. californicus colonies contain a high frequency of feed-forward interaction patterns consistent with those of complex regulatory systems. Furthermore, the scaling of these communication pathways with size is a plausible mechanism for the regulation of whole-colony metabolic scaling. The continued development of a network theory approach to integrating behavior and metabolism will reveal insights into the evolution of collective animal behavior, ecological dynamics, and social cohesion.
ContributorsWaters, James S., 1983- (Author) / Harrison, Jon F. (Thesis advisor) / Quinlan, Michael C. (Committee member) / Pratt, Stephen C. (Committee member) / Fewell, Jennifer H. (Committee member) / Gadau, Juergen (Committee member) / Arizona State University (Publisher)
Created2012
148283-Thumbnail Image.png
Description

Every year, nearly 1.5 shelter animals are euthanized.(1) By the end of 2020, California was reported to be responsible for the second most dog euthanasia’s in the United States, behind Texas by nearly 15,000 dogs. Sadly, these numbers do not include the euthanizing of cats which is generally a fraction

Every year, nearly 1.5 shelter animals are euthanized.(1) By the end of 2020, California was reported to be responsible for the second most dog euthanasia’s in the United States, behind Texas by nearly 15,000 dogs. Sadly, these numbers do not include the euthanizing of cats which is generally a fraction larger. Additionally, a majority of numbers tallied by euthanasia centers do not include animals that younger than 1 month old and under 2 pounds. These animals are referred to as “neonate,” which is essentially unsavable newborns. In fact, the New York Times writes, “Many of the shelters do not track outcomes uniformly or make historical data readily available online. Until recently, there has not been a concerted national effort to standardize and compile shelter records.”(2) If these numbers were to be included, we would see a large spike for shelter euthanasia’s in every state. <br/>Traveling Paws is a 501(c)3 Nonprofit Organization that was created to help reduce the number of shelter and stray animals euthanized in California. Our mission is to rehome animals from dangerous environments and kill shelters into their “forever homes,” or shelter facilities where they then can further be adopted and live out the rest of their lives happily. In addition to animal relocation, our team has begun programs such as sheltering, fostering, and put an emphasis on a trap, neuter, and return program to help increase the health and safety, while reducing reproduction rates of stray cats in the Southern California region. While we have been able to substantially help animals located in areas of Southern California, our work is nowhere near complete. <br/>Through this write up, I will tell you the story of my journey, creating and managing our nonprofit organization, along with our successes, problems faced, business plans to help guide us toward our future goals and success, and what I have learned throughout the process.

ContributorsRhodes, Colton A (Author) / Eaton, John (Thesis director) / Mokwa, Michael (Committee member) / Dean, W.P. Carey School of Business (Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
148189-Thumbnail Image.png
Description

This study was conducted to determine the difference in compressive strength between decayed and healthy teeth. The teeth were subjected to a compressive force to simulate the process of mastication. This was done to show that healthy teeth would be better at handling these compressive forces since they have more

This study was conducted to determine the difference in compressive strength between decayed and healthy teeth. The teeth were subjected to a compressive force to simulate the process of mastication. This was done to show that healthy teeth would be better at handling these compressive forces since they have more enamel. 26 teeth samples were collected (19 molars, 4 canines, and 3 premolars) evenly distributed between healthy and decayed. The samples were dimensionally analyzed using electronic calipers and then categorized as either decayed or healthy. The samples were then placed in a nut bolt with epoxy so that the samples could be compressed. Each sample was recorded on video while they were being exposed to the compressive force. This was done to observe how the samples were coming in contact with the Shimadzu compression machine. The amount of force that was required for the samples to exhibit the first point of breakage was recorded by the machine in pounds of force. Various analyses were conducted to determine relationships between several variables. The results showed that as the total and occlusal surface area increased, so did the amount of force the samples could absorb before breakage. As the machine came in contact with more cusps among the molar samples, those samples were able to absorb a larger compressive force. The average force that the decayed and healthy molar samples endured before breakage was roughly even, with the decayed samples average being slightly greater.

ContributorsHenscheid, Keaton J (Author) / Quaranta, Kimberly (Thesis director) / Peoples, Samuel (Committee member) / College of Health Solutions (Contributor) / Dean, W.P. Carey School of Business (Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
148191-Thumbnail Image.png
Description

This thesis examines the value creation potential of renovating an existing commercial real estate asset to a medical office. It begins by examining commercial real estate and the medical sector at a high level. It then discusses the various criteria used to select a subject property for renovation. This renovation

This thesis examines the value creation potential of renovating an existing commercial real estate asset to a medical office. It begins by examining commercial real estate and the medical sector at a high level. It then discusses the various criteria used to select a subject property for renovation. This renovation is then depicted through a modified pitch book that contains a financial model and pro forma.

ContributorsBerger, Nicholas James (Co-author) / Larrea, Justin (Co-author) / Peters, Matthew (Co-author) / Simonson, Mark (Thesis director) / Gray, William (Committee member) / School of Accountancy (Contributor) / Dean, W.P. Carey School of Business (Contributor) / Department of Finance (Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
Description

The academic environment has historically been somewhat slow to implement and adopt new technologies. However, developments in video games have created an opportunity for students to learn new skills and topics through nontraditional mediums of education. The disruption caused by the COVID-19 pandemic further highlighted the need for flexible learning

The academic environment has historically been somewhat slow to implement and adopt new technologies. However, developments in video games have created an opportunity for students to learn new skills and topics through nontraditional mediums of education. The disruption caused by the COVID-19 pandemic further highlighted the need for flexible learning opportunities. Joystick Education is our approach to addressing this need. Through online, game-based tutoring and a database of video games with high educational value, Joystick Education creates a learning environment that is effective, fun, and engaging for students. We analyzed popular, mainstream video games for educational content and selected nine games that teach concepts like history, biology, or physics while playing the game. Through promotion on social media, we generated buzz around our website which led to 103 unique visitors over our first month online and two customers requesting to book our tutoring service. We are confident that given more time to grow, Joystick Education can generate profit and become a successful business.

ContributorsVanlue, Aleczander Bryce (Co-author) / Bartels, Parker (Co-author) / Barrong, Tanner (Co-author) / Byrne, Jared (Thesis director) / Pierce, John (Committee member) / Department of Marketing (Contributor) / Department of Management and Entrepreneurship (Contributor, Contributor) / Dean, W.P. Carey School of Business (Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
148327-Thumbnail Image.png
Description

Stress for college students is nothing new and as more kids go to college the number of cases are on the rise. This issue is apparent at colleges across the nation including Arizona State University. StreetWise aims to help students prevent or appropriately deal with stress through interactive lessons teaching

Stress for college students is nothing new and as more kids go to college the number of cases are on the rise. This issue is apparent at colleges across the nation including Arizona State University. StreetWise aims to help students prevent or appropriately deal with stress through interactive lessons teaching students life skills, social skills, and emotional intelligence.<br/>In order to prove the value of our service, StreetWise conducted a survey that asked students about their habits, thoughts on stress, and their future. Students from Arizona State University were surveyed with questions on respondent background, employment, number one stressor, preferred learning method, and topics that students were interested in learning. We found that students’ number one stressor was school but was interested in learning skills that would prepare them for their future after graduation. We used the results to make final decisions so that StreetWise could offer lessons that students would get the most value out of. This led to us conducting a second survey which included mock ups of the website, examples of interactive lesson plans, and an overview of the app. Students from the first survey were surveyed in addition to new respondents. This survey was intended for us to ensure that our service would maintain its value to students with the aesthetic and interface that we envisioned.

ContributorsCompton, Katherine May (Co-author) / Ahir, Hiral (Co-author) / Ward, William (Co-author) / Byrne, Jared (Thesis director) / Hall, Rick (Committee member) / Dean, W.P. Carey School of Business (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2021-05