Matching Items (32)
Description
This project was designed to develop resources to highlight diverse career options for students achieving a degree within the School of Life Sciences. Many students have a very narrow view of what careers their degree prepares them for. In addition, if they have a career in mind, they have difficulty selecting an appropriate degree that will prepare them for their intended career. The goal of this project was to provide a broader view of career options, as well as illustrate the requirements each student would need to meet in order to pursue these careers. This was done by interviewing five career professionals and developing a major map that corresponds to the specific requirements of that career.
ContributorsBaber, Ariel Kate Elven (Author) / Wilson Sayres, Melissa (Thesis director) / DeNardo, Dale (Committee member) / Downing, Virginia (Committee member) / School of Life Sciences (Contributor) / School of Mathematical and Statistical Sciences (Contributor) / School of International Letters and Cultures (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
Description
Vertebral osteology varies greatly among snake species. This variation may be related to specialization in microhabitat and prey-capture. Radiographs of eight preserved male specimens were taken in order to analyze the vertebral length and morphology of snakes which exhibit extreme characteristics in microhabitat utilization and prey-capture methods (highly arboreal, effective constrictor). This group includes two representatives each from four major families within Serpentes: Boidae, Pythonidae, Viperidae, and Colubridae. The four boids and pythons are effective constrictors, while the four vipers and colubrids are non-constricting. One specimen of each pair is highly arboreal, while the other is terrestrial. Findings support previous research in that constrictors had larger total numbers of vertebrae than non-constrictors. When average maximum adult length and morphology of axial musculature was taken into consideration, however, flexibility gained by vertebral number alone does not theoretically confer a mechanical advantage during constriction, at least among the specimens examined. All arboreal specimens had tails with a greater number of vertebrae than their con-familial terrestrial counterpart, implicating greater flexibility in the caudal region as an important characteristic for arboreality across taxa. Examination of segments of 10 vertebrae revealed that the greatest vertebral elongation occurred at the midpoint of the thoracic region. Reduction in size and length of tail vertebrae appears to occur independently of thoracic vertebrae. Colubrids, specifically, demonstrated a unique caudal vertebral elongation pattern which could potentially be advantageous for quick locomotion. These results indicate that caudal morphology may be more important in behavioral specialization than previously thought.
ContributorsGuerrero, Anna Clemencia (Author) / Fisher, Rebecca (Thesis director) / DeNardo, Dale (Committee member) / Elliott, Steve (Committee member) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2016-12
Description
There is considerable recent interest in the dynamic nature of immune function in the context of an animal’s internal and external environment. An important focus within this field of ecoimmunology is on how availability of resources such as energy can alter immune function. Water is an additional resource that drives animal development, physiology, and behavior, yet the influence hydration has on immunity has received limited attention. In particular, hydration state may have the greatest potential to drive fluctuations in immunity and other physiological functions in species that live in water-limited environments where they may experience periods of dehydration. To shed light on the sensitivity of immune function to hydration state, I first tested the effect of hydration states (hydrated, dehydrated, and rehydrated) and digestive states on innate immunity in the Gila monster, a desert-dwelling lizard. Though dehydration is often thought to be stressful and, if experienced chronically, likely to decrease immune function, dehydration elicited an increase in immune response in this species, while digestive state had no effect. Next, I tested whether dehydration was indeed stressful, and tested a broader range of immune measures. My findings validated the enhanced innate immunity across additional measures and revealed that Gila monsters lacked a significant stress hormone response during dehydration (though results were suggestive). I next sought to test if life history (in terms of environmental stability) drives these differences in dehydration responses using a comparative approach. I compared four confamilial pairs of squamate species that varied in habitat type within each pair—four species that are adapted to xeric environments and four that are adapted to more mesic environments. No effect of life history was detected between groups, but hydration was a driver of some measures of innate immunity and of stress hormone concentrations in multiple species. Additionally, species that exhibited a stress response to dehydration did not have decreased innate immunity, suggesting these physiological responses may often be decoupled. My dissertation work provides new insight into the relationship between hydration, stress, and immunity, and it may inform future work exploring disease transmission or organismal responses to climate change.
ContributorsMoeller, Karla T (Author) / DeNardo, Dale (Thesis advisor) / Angilletta, Michael (Committee member) / French, Susannah (Committee member) / Rutowski, Ronald (Committee member) / Sabo, John (Committee member) / Arizona State University (Publisher)
Created2016
Description
In species with highly heteromorphic sex chromosomes, the degradation of one of the sex chromosomes can result in unequal gene expression between the sexes (e.g., between XX females and XY males) and between the sex chromosomes and the autosomes. Dosage compensation is a process whereby genes on the sex chromosomes achieve equal gene expression which prevents deleterious side effects from having too much or too little expression of genes on sex chromsomes. The green anole is part of a group of species that recently underwent an adaptive radiation. The green anole has XX/XY sex determination, but the content of the X chromosome and its evolution have not been described. Given its status as a model species, better understanding the green anole genome could reveal insights into other species. Genomic analyses are crucial for a comprehensive picture of sex chromosome differentiation and dosage compensation, in addition to understanding speciation.
In order to address this, multiple comparative genomics and bioinformatics analyses were conducted to elucidate patterns of evolution in the green anole and across multiple anole species. Comparative genomics analyses were used to infer additional X-linked loci in the green anole, RNAseq data from male and female samples were anayzed to quantify patterns of sex-biased gene expression across the genome, and the extent of dosage compensation on the anole X chromosome was characterized, providing evidence that the sex chromosomes in the green anole are dosage compensated.
In addition, X-linked genes have a lower ratio of nonsynonymous to synonymous substitution rates than the autosomes when compared to other Anolis species, and pairwise rates of evolution in genes across the anole genome were analyzed. To conduct this analysis a new pipeline was created for filtering alignments and performing batch calculations for whole genome coding sequences. This pipeline has been made publicly available.
In order to address this, multiple comparative genomics and bioinformatics analyses were conducted to elucidate patterns of evolution in the green anole and across multiple anole species. Comparative genomics analyses were used to infer additional X-linked loci in the green anole, RNAseq data from male and female samples were anayzed to quantify patterns of sex-biased gene expression across the genome, and the extent of dosage compensation on the anole X chromosome was characterized, providing evidence that the sex chromosomes in the green anole are dosage compensated.
In addition, X-linked genes have a lower ratio of nonsynonymous to synonymous substitution rates than the autosomes when compared to other Anolis species, and pairwise rates of evolution in genes across the anole genome were analyzed. To conduct this analysis a new pipeline was created for filtering alignments and performing batch calculations for whole genome coding sequences. This pipeline has been made publicly available.
ContributorsRupp, Shawn Michael (Author) / Wilson Sayres, Melissa A (Thesis advisor) / Kusumi, Kenro (Committee member) / DeNardo, Dale (Committee member) / Arizona State University (Publisher)
Created2016
Description
In wild birds, the stress response can inhibit the activity of the innate immune system, which serves as the first line of defense against pathogens. By elucidating the mechanisms which regulate the interaction between stress and innate immunity, researchers may be able to predict when birds experience increased susceptibility to infections and can target specific mediators to mitigate stress-induced suppression of innate immune activity. Such elucidation is especially important for urban birds, such as the House Sparrow (Passer domesticus), because these birds experience higher pathogen prevalence and transmission when compared to birds in rural regions. I investigated the role of corticosterone (CORT) in stress-induced suppression of two measures of innate immune activity (complement- and natural antibody-mediated activity) in male House Sparrows. Corticosterone, the primary avian glucocorticoid, is elevated during the stress response and high levels of this hormone induce effects through the activation of cytosolic and membrane-bound glucocorticoid receptors (GR). My results demonstrate that CORT is necessary and sufficient for stress-induced suppression of complement-mediated activity, and that this relationship is consistent between years. Corticosterone, however, does not inhibit complement-mediated activity through cytosolic GR, and additional research is needed to confirm the involvement of membrane-bound GR. The role of CORT in stress-induced inhibition of natural antibody-mediated activity, however, remains puzzling. Stress-induced elevation of CORT can suppress natural antibody-mediated activity through the activation of cytosolic GR, but the necessity of this mechanism varies inter-annually. In other words, both CORT-dependent and CORT-independent mechanisms may inhibit natural antibody-mediated activity during stress in certain years, but the causes of this inter-annual variation are not known. Previous studies have indicated that changes in the pathogen environment or food availability can alter regulation of innate immunity, but further research is needed to test these hypotheses. Overall, my dissertation demonstrates that stress inhibits innate immunity through several mechanisms, but environmental pressures may influence this inhibitory relationship.
ContributorsGao, Sisi (Author) / Deviche, Pierre (Thesis advisor) / DeNardo, Dale (Committee member) / McGraw, Kevin (Committee member) / Orchinik, Miles (Committee member) / Moore, Michael C. (Committee member) / Arizona State University (Publisher)
Created2017
Description
Many animals thermoregulate to maximize performance. However, interactions with other animals, such as competitors or predators, limit access to preferred microclimates. For instance, an animal may thermoregulate poorly when fighting rivals or avoiding predators. However, the distribution of thermal resources should influence how animals perceive and respond to risk. When thermal resources are concentrated in space, individuals compete for access, which presumably reduces the thermoregulatory performance while making their location more predictable to predators. Conversely, when thermal resources are dispersed, several individuals can thermoregulate effectively without occupying the same area. Nevertheless, interactions with competitors or predators impose a potent stress, often resulting in both behavioral and physiological changes that influence thermoregulation. To assess the costs of intraspecific competition and predation risk during thermoregulation, I measured thermoregulation, movement, and hormones of male lizards (Sceloporus jarrovi) in experiment landscapes, with clumped to patchy distributions of microclimates. I found lizards aggressively competed for access to microclimates, with larger males gaining priority access when thermal resources were aggregated. Competition reduced thermoregulatory performance, increased movements, and elevated plasma corticosterone in large and small males. However, the magnitude of these responses decreased as the patchiness of the thermal environment increased. Similarly, under simulated predation risk, lizards reduced thermoregulatory performance, decreased movements, and elevated plasma corticosterone. Again, with the magnitude of these responses decreased with increasing thermal patchiness. Interestingly, even without competitors or predators, lizards in clumped arenas moved greater distances and circulated more corticosterone than did lizards in patchy arenas, indicating the thermal quality of the thermal landscape affected the energetic demands on lizards. Thus, biologists should consider species interactions and spatial structure when modeling impacts of climate change on thermoregulation.
ContributorsRusch, Travis W (Author) / Angilletta, Michael (Thesis advisor) / Sears, Mike (Committee member) / DeNardo, Dale (Committee member) / Deviche, Pierre (Committee member) / McGraw, Kevin (Committee member) / Arizona State University (Publisher)
Created2017
Description
Desert environments provide considerable challenges to organisms because of high temperatures and limited food and water resources. Accordingly, desert species have behavioral and physiological traits that enable them to cope with these constraints. However, continuing human activity as well as anticipated further changes to the climate and the vegetative community pose a great challenge to such balance between an organism and its environment. This is especially true in the Arabian Desert, where climate conditions are extreme and environmental disturbances substantial. This study combined laboratory and field components to enhance our understanding of dhub (Uromastyx aegyptius) ecophysiology and determine whether habitat protection influences dhub behavior and physiology.
Results of this study showed that while body mass and body condition consistently diminished as the active season progressed, they were both greater in protected habitats compared to non-protected habitats, regardless of season. Dhubs surface activity and total body water decreased while evaporative water loss and body temperature increased as the active season progressed and ambient temperature got hotter. Total body water was also significantly affected by habitat protection.
Overall, this study revealed that, while habitat protection provided more vegetation, it had little effect on seasonal changes in surface activity. While resource availability in protected areas might allow for larger dhub populations, unprotected areas showed similar body morphometrics, activity, and body temperatures. By developing an understanding of how different coping strategies are linked to particular ecological, morphological, and phylogenetic traits, we will be able to make more accurate predictions regarding the vulnerability of species. By combining previous studies pertaining to conservation of protected species with the results of my study, a number of steps in ecosystem management are recommended to help in the preservation of dhubs in the Kuwaiti desert.
Results of this study showed that while body mass and body condition consistently diminished as the active season progressed, they were both greater in protected habitats compared to non-protected habitats, regardless of season. Dhubs surface activity and total body water decreased while evaporative water loss and body temperature increased as the active season progressed and ambient temperature got hotter. Total body water was also significantly affected by habitat protection.
Overall, this study revealed that, while habitat protection provided more vegetation, it had little effect on seasonal changes in surface activity. While resource availability in protected areas might allow for larger dhub populations, unprotected areas showed similar body morphometrics, activity, and body temperatures. By developing an understanding of how different coping strategies are linked to particular ecological, morphological, and phylogenetic traits, we will be able to make more accurate predictions regarding the vulnerability of species. By combining previous studies pertaining to conservation of protected species with the results of my study, a number of steps in ecosystem management are recommended to help in the preservation of dhubs in the Kuwaiti desert.
ContributorsAl-Sayegh, Mohammed (Author) / DeNardo, Dale (Thesis advisor) / Angilletta, Michael (Committee member) / Smith, Andrew (Committee member) / Sabo, John (Committee member) / Majeed, Qais (Committee member) / Arizona State University (Publisher)
Created2017
Description
An organism's ability to maintain optimal body temperature is extremely important for sustaining physiological and behavioral processes necessary for survival. However, like other physiological systems, thermobiology can be influenced by the availability of resources. Water is a vital resource that has profound implications on many aspects of biological function, including thermoregulatory pathways. However, water availability has a tendency fluctuate within any given ecosystem. While several studies have investigated the influence of water availability on a range of thermoregulatory pathways, very little attention has been given to its influence on Voluntary Maximum Temperature (VMT). We investigated the effects of dehydration on Voluntary Maximum Temperature in a captive population of Gila monsters (Heloderma suspectum). Gila monsters are large-bodied, desert dwelling lizards that experience periods of seasonal dehydration. Additionally, the effects of dehydration on their physiology and behavior have been extensively studied. We hypothesized that dehydration would reduce VMT. As expected, there was a significant decrease in exit temperature as blood osmolality increased. This is presumed to be in an effort to decrease water loss. Adaptations that allow desert dwelling organisms to conserve water are highly advantageous due to seasonal water constraints. Our findings offer insight on how the behavior of these organisms may change in response to changes in climate.
ContributorsHartson, Callie Elizabeth (Author) / DeNardo, Dale (Thesis director) / Angilletta, Michael (Committee member) / Camacho, Agus (Committee member) / School of Life Sciences (Contributor) / School of Human Evolution and Social Change (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
Objective: To explore the dimensions of the human animal bond and provide a community needs assessment to inform the community stake holders such as the Arizona Humane Society and Nina Mason Pulliam Charitable Trust Foundation how many animals are in need of veterinary services within the homeless population of Phoenix, Arizona. In addition to this, pets of the homeless individuals will be able to gain access to veterinary services for eight consecutive weeks. Background: Pets have an important impact on human mental, physical, social, and emotional health. It has been reported that about one third of the homeless population in Arizona has pets that are not able to gain access to veterinary care (Wang, 2015). Most homeless shelters will not allow people to access services with pets. As a consequence people will sleep out in the streets. Animals as Lifechangers and Lifesavers: Pets in the Redemption Narratives of Homeless People (Irvine, 2013) contains interviews of homeless people based on their life stories. A common theme among interviewees was that they felt they had a responsibility to their pets that served as a motivating purpose for giving up horrible personal habits because they had a sense of responsibility. Methods/Materials: Wandering Paws was launched in February 2015, but did not officially start as an eight-week study until March 2016. This pilot program serves the homeless populations' dogs and cats with veterinary care. The Arizona Humane Society was approached to acquire their services for this project including a veterinarian, a technician, and usage of their seventy-one foot mobile unit. Homeless individuals who wanted veterinary services were recruited and asked to fill out a twenty-three-question survey. Secondary data was procured from the Arizona Humane Society about the animal and services rendered for that pet. Results: Over the course of the first four weeks 22 surveys have been completed. 86% of the surveys completed indicate a strong bond between the owner and animal. The remaining 14% of the surveys completed indicate a weaker bond between the animal and owner. Conclusion/Implications: The research indicates a strong connection between most people and their animals. The veterinary services provided for the homeless population should be continued on a monthly basis as a wellness clinic in the future, as these services are in great demand.
ContributorsHowarth, Amber (Author) / DeNardo, Dale (Thesis director) / Thatcher, Craig (Committee member) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
Suicide is one of the leading causes of death worldwide and statistical analysis of suicide by profession reveals that physicians and veterinarians experience abnormally high suicide rates. This paper seeks to provide a comprehensive literature review over what some general theories of suicide are, why these professions exhibit high suicide rates, what assistance is currently being provided, and where do these assistance efforts succeed or fail. Moreover, this paper addresses what advancements may be made within these fields to further combat suicide in physicians and veterinarians. To achieve this, general theories behind suicide, risk factors unique to or heavily prevalent in these professions, and current assistance efforts are read, organized, and summarized.<br/><br/>A summary of these risk factors includes stress and mental health disorders accumulated through school and work, personal and professional isolation, access to lethal substances, suicide contagion, exposure to euthanasia, and the role of perfectionism. There are several assistance efforts in place with the most successful ones being highly personalized, but many are still underutilized. Moreover, the stigma of suicide pervades these professions and is addressed by several researchers as something to combat or prevent. Going forward, it is hopeful that not only will more assistance efforts will be created and provided for physicians and veterinarians suffering from suicidal tendencies, but efforts to reduce the stigma of suicide be implemented and utilized as soon as possible.
ContributorsSinclair, Andrew (Author) / DeNardo, Dale (Thesis director) / Sterner, Beckett (Committee member) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2021-05