Matching Items (102)
Description
By increasing the mean and variance of environmental temperatures, climate change has caused local extinctions and range shifts of numerous species. However, biologists disagree on which populations and species are most vulnerable to future warming. This debate arises because biologists do not know which physiological processes are most vulnerable to temperature or how to model these processes in complex environments. Using the South American locust (Schistocerca cancellata) as a model system, my dissertation addressed this debate and explained how climate limits the persistence of locust populations. Locusts of S. cancellata are serious agricultural pests with occasional outbreaks covering up to 4 million km2 over six countries. Because outbreaks are largely driven by climate, understanding how climate limits the persistence of locusts may help predict crop losses in future climates. To achieve this aim, I integrated observational, experimental, and computational approaches. First, I tested a physiological model of heat stress. By measuring the heat tolerance of locusts under different oxygen concentrations, I demonstrated that heat tolerance depends on oxygen supply during the hatchling stage only. Second, I modeled the geographic distribution of locusts using physiological traits. I started by measuring thermal effects on consumption and defecation of field-captured locusts, and I then used these data to model energy gain in current and future climates. My results indicated that incorporating physiological mechanisms can improve the accuracy of models and alter predicted impacts of climate change. Finally, I explored the causes and consequences of intraspecific variation in heat tolerance. After measuring heat tolerance of locusts in different hydration states and developmental stages, I modeled survival in historical microclimates. My models indicated that recent climate change has amplified the risk of overheating for locusts, and this risk depended strongly on shade availability, hydration state, and developmental stage. Therefore, the survival of locusts in future climates will likely depend on their access to shade and water. Overall, my dissertation argues that modeling physiological mechanisms can improve the ability of biologists to predict the impacts of climate change.
ContributorsYoungblood, Jacob (Author) / Angilletta, Michael (Thesis advisor) / Buckley, Lauren (Committee member) / Cease, Arianne (Committee member) / Smith, Brian (Committee member) / Vanden Brooks, John (Committee member) / Arizona State University (Publisher)
Created2022
Description
Transorbital surgery has gained recent notoriety due to its incorporation into endoscopic skull base surgery. The body of published literature on the field is cadaveric and observation. The pre-clinical studies are focused on the use of the endoscope only. Furthermore the methodology utilised in the published literature is inconsistent and does not embody the optimal principles of scientific experimentation. This body of work evaluates a minimally invasive novel surgical corridor - the transorbital approach - its validity in neurosurgical practice, as well as both qualitatively and quantitatively assessing available technological advances in a robust experimental fashion. While the endoscope is an established means of visualisation used in clinical transorbital surgery, the microscope has never been assessed with respect to the transorbital approach. This question is investigated here and the anatomical and surgical benefits and limitations of microscopic visualisation demonstrated. The comparative studies provide increased knowledge on specifics pertinent to neurosurgeons and other skull base specialists when planning pre-operatively, such as pathology location, involved anatomical structures, instrument maneuvrability and the advantages and disadvantages of the distinct visualisation technologies. This is all with the intention of selecting the most suitable surgical approach and technology, specific to the patient, pathology and anatomy, so as to perform the best surgical procedure. The research findings illustrated in this body of work are diverse, reproducible and applicable. The transorbital surgical corridor has substantive potential for access to the anterior cranial fossa and specific surgical target structures. The neuroquantitative metrics investigated confirm the utility and benefits specific to the respective visualisation technologies i.e. the endoscope and microscope. The most appropriate setting wherein the approach should be used is also discussed. The transorbital corridor has impressive potential, can utilise all available technological advances, promotes multi-disciplinary co-operation and learning amongst clinicians and ultimately, is a means of improving operative patient care.
ContributorsHoulihan, Lena Mary (Author) / Preul, Mark C. (Thesis advisor) / Vernon, Brent (Thesis advisor) / O' Sullivan, Michael G.J. (Committee member) / Lawton, Michael T. (Committee member) / Santarelli, Griffin (Committee member) / Smith, Brian (Committee member) / Arizona State University (Publisher)
Created2021
Description
In 1996, a floral and faunal inventory of the southeastern slopes of the Marojejy Massif, which falls in a protected area known as the Parc national de Marojejy, was conducted in an ascending series of altitudinal transect zones. The 1996 research team worked in five altitudinal zones (referred to as transect zones). Between 3 October and 15 November 2021, a floral and faunal inventory was completed, replicating the locations surveyed in 1996 and closely the dates. Detected bird species were analyzed for changes in elevational distribution between 1996 and 2021. Birds were divided into three feeding behavior groups and tolerance to forest habitat degradation was considered.
ContributorsLangrand, Tahiry (Author) / Schoon, Michael (Thesis director) / Goodman, Steve (Committee member) / Barrett, The Honors College (Contributor) / School of Complex Adaptive Systems (Contributor) / School of International Letters and Cultures (Contributor) / School of Sustainability (Contributor)
Created2022-05
Description
Political boundaries often divide ecosystems and create the challenge of conserving the ecosystem across borders. Through transboundary ecosystem management multiple groups can come together and manage the ecosystem that spans their borders collaboratively. In the United States there are several examples of ecosystems that span borders, such as the Sonoran Desert along the US-Mexico frontier and the Rocky Mountains running through the US and Canada. To gain insight into what leads to effective transboundary resource management I compared two case studies that manage resources over borders with multiple collaborators: Glacier National Park and Organ Pipe Cactus National Monument. These two cases offer contrasting ecosystems and backgrounds in transboundary resource management in the United States. To compare the cases I coded them using a collaborative governance codebook (Schoon et al. 2020). The codebook uses a Context-Mechanisms-Outcomes framework to identify aspects of collaborative governance and contextual factors present in each park (Pawson & Tilley 1997; Salter & Kothari, 2014). Once coded, the cases were compared to identify what aspects were similar and different in the parks to help potentially explain what features did or did not lead to effective transboundary resource management.
ContributorsTaetle, Noah (Author) / Schoon, Michael (Thesis director) / Carr Kelman, Candice (Committee member) / Barrett, The Honors College (Contributor) / School of Sustainability (Contributor) / School of Politics and Global Studies (Contributor)
Created2022-05
Description
Heavy metals and persistent organic pollutants contribute to human health risks worldwide. Among the most common routes of exposure to pollutants for humans are through the consumption of contaminated water and food, with fish being among the greatest vectors for ingestion of heavy metals in humans, particularly mercury.This dissertation consists of three chapters with a central theme of investigating heavy metal and persistent organic pollutant concentrations in fish and corned beef, which are two commonly consumed food items in American Samoa. A literature review illustrated that historically the primary pollutants of concern in fish muscle tissue from American Samoa have been mercury, arsenic, and polycyclic aromatic hydrocarbon mixtures. To better understand the changes in heavy metals and persistent organic pollutants in fish, this study reports an updated data set, comparing concentrations in pollutants as they have changed over time. To further investigate pollutants in fish tissue, 77 locally caught and commonly consumed fish were analyzed for heavy metals and persistent organic pollutants, and baseline human health risk assessments were calculated for contaminants that had available oral reference doses. While in American Samoa collecting fish for contaminant analyses, it was realized that canned corned beef appeared to be more commonly consumed than fresh fish. An IRB approved consumption survey revealed that 89% of American Samoan adults regularly consume fish, which is the same percentage of people that reported eating canned corned beef, indicating a dramatic increase in this food item to their diet since its introduction in the 20th century.
Results of this study indicate that fish muscle tissue generally has higher heavy metal concentrations than canned corned beef, and that mercury continues to be a main contaminant of concern when consuming fresh and canned fish in American Samoa. While none of the heavy metal concentrations in corned beef exceeded calculated action levels, these foods might contribute to negative health outcomes in other ways. One of the main findings of this study is that either the presence or the ability to detect persistent organic pollutant concentrations are increasing in fish tissue and should be periodically monitored to adequately reflect current conditions.
ContributorsLewis, Tiffany Beth (Author) / Polidoro, Beth (Thesis advisor) / Neuer, Susanne (Thesis advisor) / Halden, Rolf (Committee member) / Schoon, Michael (Committee member) / Arizona State University (Publisher)
Created2023
Description
Olfactory perception is a complex and multifaceted process that involves the detection of volatile organic compounds by olfactory receptor neurons in the nasal neuroepithelium. Different odorants can elicit different perceived intensities at the same concentration, while direct intensity ratings are vulnerable to framing effects and inconsistent scale usage. Odor perception is genetically determined, with each individual having a unique olfaction "footprint" and sensitivity levels. Genetic factors, age, gender, race, and environmental factors influence olfactory acuity. The olfactory system's complexity makes it challenging to create a standardized comparison system for olfactory perception tests. The COVID-19 pandemic has underscored the importance of olfactory dysfunction, particularly the loss of smell and taste as common symptoms. Research has demonstrated the widespread occurrence of olfactory impairment in various populations, often stemming from post-viral origins, which is the leading cause of permanent smell loss. Utilizing quantitative ranking on a qualitative scale enhances the precision and accuracy when evaluating and drawing conclusions about odor perception and how to mitigate problems caused by external factors. Pairwise comparisons enhance the accuracy and consistency of results and provide a more intuitive way of comparing items. Such ranking techniques can lead to early detection of olfactory disorders and improved diagnostic tools. The COVID-19 pandemic has shed light on the significance of olfactory dysfunction, emphasizing the need for further research and standardized testing methods in olfactory perception.
ContributorsDarden, Jaelyn (Author) / Smith, Brian (Thesis advisor) / Gerkin, Richard (Thesis advisor) / Spackman, Christy (Committee member) / Arizona State University (Publisher)
Created2023
Description
Development of the central nervous system is an incredible process that relies on multiple extracellular signaling cues and complex intracellular interactions. Approximately 1500 genes are associated with neurodevelopmental disorders, many of which are linked to a specific biochemical signaling cascade known as Extracellular-Signal Regulated Kinase (ERK1/2). Clearly defined mutations in regulators of the ERK1/2 pathway cause syndromes known as the RASopathies. Symptoms include intellectual disability, developmental delay, cranio-facial and cardiac deficits. Treatments for RASopathies are limited due to an in complete understanding of ERK1/2’s role in brain development. Individuals with Neurofibromatosis Type and Noonan Syndrome, the two most common RASopathies, exhibit aberrant functional and white matter organization in non-invasive imaging studies, however, the contributions of neuronal versus oligodendrocyte deficits to this phenotype are not fully understood. To define the cellular functions of ERK1/2 in motor circuit formation, this body of work focuses on two long-range projection neuron subtypes defined by their neurotransmitter. With genetic mouse models, pathological ERK1/2 in glutamatergic neurons reduces axonal outgrowth, resulting in deficits in activity dependent gene expression and the ability to learn a motor skill task. Restricting pathological ERK1/2 within cortical layer V recapitulates these wiring deficits but not the behavioral learning phenotype. Moreover, it is uncovered that pathological ERK1/2 results in compartmentalized expression pattern of phosphorylated ERK1/2. It is not clear whether ERK1/2 functions are similar in cholinergic neuron populations that mediate attention, memory, and motor control. Basal forebrain cholinergic neuron development relies heavily on NGF-TrKA neurotrophic signaling known to activate ERK1/2. Yet the function of ERK1/2 during cholinergic neuronal specification and differentiation is poorly understood. By selectively deleting ERK1/2 in cholinergic neurons, ERK1/2 is required for activity-dependent maturation of neuromuscular junctions in juvenile mice, but not the establishment of lower motor neuron number. Moreover, ERK1/2 is not required for specification of choline acetyltransferase expressing basal forebrain cholinergic neurons by 14 days of age. However, ERK1/2 may be necessary for BFCN maturation by adulthood. Collectively, these data indicate that glutamatergic neuron-autonomous decreases in long-range axonal outgrowth and modest effects on later stages of cholinergic neuron maintenance may be important aspects of neuropathogenesis in RASopathies.
ContributorsRees, Katherina Pavy (Author) / Newbern, Jason (Thesis advisor) / Olive, Foster (Committee member) / Qiu, Shenfeng (Committee member) / Sattler, Rita (Committee member) / Smith, Brian (Committee member) / Arizona State University (Publisher)
Created2024
Description
Effective collaboration and cooperation across difference are at the heart of present and future sustainability challenges and solutions. Collaboration among social groups (intragenerational), across time (intergenerational), and across species (interspecies) is each central to achieving sustainability transitions in the 21st century. In practice, there are three types of differences that limit collaboration and cooperation toward sustainability outcomes: differences among social groups, differences across time, and differences across species. Each of these differences have corresponding cognitive biases that challenge collaboration. Social cognitive biases challenge collaboration among social groups; temporal cognitive biases challenge collaboration across time; and anthropocentric cognitive biases challenge collaboration across species. In this work, I present three correctives to collaboration challenges spanning the social, temporal, and species cognitive biases through intervention-specific methods that build beyond traditional framings of empathy, toward social, futures, and ecological empathy. By re-theorizing empathy across these domains, I seek to construct a multidimensional theory of empathy for sustainability, and suggest methods to build it, to bridge differences among people, time horizons, and species for sustainability practice.
ContributorsLambert, Lauren Marie-Jasmine (Author) / Selin, Cynthia (Thesis advisor) / Schoon, Michael (Thesis advisor) / Tomblin, David (Committee member) / Berbés-Blázquez, Marta (Committee member) / Arizona State University (Publisher)
Created2023
Description
Wildlife rehabilitation as a practice in the United States exists in a complicated ethical landscape. The Wildlife Rehabilitator's Code of Ethics exists to guide the profession and states that rehabilitators must respect the wildness and maintain the dignity of an animal in their care. This thesis explores the question: How do the attitudes and actions of wildlife rehabilitators exemplify the ways in which they understand and enact respect for an animal’s dignity and wildness while in their care? Additionally, in what circumstances do rehabilitators align and diverge from each other in their interpretation and demonstration of this respect? These questions were answered through a literature review, interviews with rehabilitators, and site visits to wildlife rehabilitation centers in the Phoenix metropolitan area. My results suggest that rehabilitators are aligned in their understanding of respect for wildness and dignity as it applies to the animals in their care that are actively undergoing rehabilitation. Rehabilitators achieved consensus on the idea that they should interact with the animals as little as possible while providing their medically necessary care. Rehabilitators began to diverge when considering the animals in their sanctuary spaces. Specifically, they varied in their perception of wildness in sanctuary animals, which informed how some saw their responsibilities to the animals. Lesser perceived wildness correlated to increased acceptance of forming affectionate relationships with the sanctuary animals, and even feelings of obligation to form these relationships. Based on my research, I argue that the Wildlife Rehabilitator's Code of Ethics should be revised to reflect the specific boundary that wildlife rehabilitators identified in the rehabilitation space and provide substantive guidance as to what respecting wildness and dignity means in this field.
ContributorsBernat, Isabella Elyse (Author) / Minteer, Ben (Thesis advisor) / Ellison, Karin (Committee member) / Schoon, Michael (Committee member) / Arizona State University (Publisher)
Created2023
Description
Though controversial in its utility to the scientific study of nonhuman animals, anthropomorphism, or the attribution of human characteristics to a nonhuman being, is omnipresent in our interactions with other animals. Anthropomorphism is undeniably a fixture of modern zoos, but how anthropomorphism relates to zoos’ contributions to conservation is unclear. In this dissertation, I investigate these potentially dueling, potentially overlapping, messages within great ape exhibits in accredited zoos. Given the complexity of both anthropomorphism and conservation, this dissertation reveals some nuances of how both play out in zoological spaces. Human psychology literature on anthropomorphism indicates that there are a variety of uses for this lens that benefit humans; from feeling we can understand a confusing animal action, to feeling social connection. Whereas the comparative psychology literature highlights a contested utility of anthropomorphism in studies of nonhuman animals. The main findings from this study are four-fold. Firstly, surveys conducted with zoo visitors show that many bring anthropomorphic beliefs with them on their trek through the zoo. Visitors are prone to viewing great apes as strikingly like humans in terms of emotions, emotional expression, and understanding of the world. Secondly, surveyed zoo visitors who agreed more with anthropomorphic statements also agreed more with statements about feeling interconnected with nature. Thirdly, there is no uniform understanding within the zoo community about how zoo exhibits do or should contribute to conservation efforts given that exhibits have multiple goals, one being the safety and wellness of their animal residents. Fourthly, interviews of zoo staff show that they mediate a variety of messages for zoo visitors and walk a sometimes-divisive line between when it’s acceptable to use anthropomorphic framing to discuss zoo animals and when it’s inaccurate. By leveraging a better understanding of these attitudes and relationships, zoos can further empower their staff to navigate these complex issues and improve their mission-based goal of promoting conservation outcomes by acknowledging the human practices embedded in our perceptions of and interactions with zoo animals. This work speaks to the importance of carefully considering the ways we understand animals in zoos, in the wild, and all the places in-between.
ContributorsLyon, Cassandra (Author) / Minteer, Ben A. (Thesis advisor) / Wynne, Clive D.L. (Committee member) / Maynard, Lily (Committee member) / Schoon, Michael (Committee member) / Arizona State University (Publisher)
Created2024