Matching Items (37)
Description
Conditions during development can shape the expression of traits at adulthood, a phenomenon called developmental plasticity. In this context, factors such as nutrition or health state during development can affect current and subsequent physiology, body size, brain structure, ornamentation, and behavior. However, many of the links between developmental and adult phenotype are poorly understood. I performed a series of experiments using a common molecular currency - carotenoid pigments - to track somatic and reproductive investments through development and into adulthood. Carotenoids are red, orange, or yellow pigments that: (a) animals must acquire from their diets, (b) can be physiologically beneficial, acting as antioxidants or immunostimulants, and (c) color the sexually attractive features (e.g., feathers, scales) of many animals. I studied how carotenoid nutrition and immune challenges during ontogeny impacted ornamental coloration and immune function of adult male mallard ducks (Anas platyrhynchos). Male mallards use carotenoids to pigment their yellow beak, and males with more beaks that are more yellow are preferred as mates, have increased immune function, and have higher quality sperm. In my dissertation work, I established a natural context for the role that carotenoids and body condition play in the formation of the adult phenotype and examined how early-life experiences, including immune challenges and dietary access to carotenoids, affect adult immune function and ornamental coloration. Evidence from mallard ducklings in the field showed that variation in circulating carotenoid levels at hatch are likely driven by maternal allocation of carotenoids, but that carotenoid physiology shifts during the subsequent few weeks to reflect individual foraging habits. In the lab, adult beak color expression and immune function were more tightly correlated with body condition during growth than body condition during subsequent stages of development or adulthood. Immune challenges during development affected adult immune function and interacted with carotenoid physiology during adulthood, but did not affect adult beak coloration. Dietary access to carotenoids during development, but not adulthood, also affected adult immune function. Taken together, these results highlight the importance of the developmental stage in shaping certain survival-related traits (i.e., immune function), and lead to further questions regarding the development of ornamental traits.
ContributorsButler, Michael (Author) / McGraw, Kevin J. (Thesis advisor) / Chang, Yung (Committee member) / Deviche, Pierre (Committee member) / DeNardo, Dale (Committee member) / Rutowski, Ronald (Committee member) / Arizona State University (Publisher)
Created2012
Description
Land management practices such as domestic animal grazing can alter plant communities via changes in soil structure and chemistry, species composition, and plant nutrient content. These changes can affect the abundance and quality of plants consumed by insect herbivores with consequent changes in population dynamics. These population changes can translate to massive crop damage and pest control costs. My dissertation focused on Oedaleus asiaticus, a dominant Asian locust, and had three main objectives. First, I identified morphological, physiological, and behavioral characteristics of the migratory ("brown") and non-migratory ("green") phenotypes. I found that brown morphs had longer wings, larger thoraxes and higher metabolic rates compared to green morphs, suggesting that developmental plasticity allows greater migratory capacity in the brown morph of this locust. Second, I tested the hypothesis of a causal link between livestock overgrazing and an increase in migratory swarms of O. asiaticus. Current paradigms generally assume that increased plant nitrogen (N) should enhance herbivore performance by relieving protein-limitation, increasing herbivorous insect populations. I showed, in contrast to this scenario, that host plant N-enrichment and high protein artificial diets decreased the size and viability of O. asiaticus. Plant N content was lowest and locust abundance highest in heavily livestock-grazed fields where soils were N-depleted, likely due to enhanced erosion and leaching. These results suggest that heavy livestock grazing promotes outbreaks of this locust by reducing plant protein content. Third, I tested for the influence of dietary imbalance, in conjunction with high population density, on migratory plasticity. While high population density has clearly been shown to induce the migratory morph in several locusts, the effect of diet has been unclear. I found that locusts reared at high population density and fed unfertilized plants (i.e. high quality plants for O. asiaticus) had the greatest migratory capacity, and maintained a high percent of brown locusts. These results did not support the hypothesis that poor-quality resources increased expression of migratory phenotypes. This highlights a need to develop new theoretical frameworks for predicting how environmental factors will regulate migratory plasticity in locusts and perhaps other insects.
ContributorsCease, Arianne (Author) / Harrison, Jon (Thesis advisor) / Elser, James (Thesis advisor) / DeNardo, Dale (Committee member) / Quinlan, Michael (Committee member) / Sabo, John (Committee member) / Arizona State University (Publisher)
Created2012
Description
Parental care provides many benefits to offspring. One widely realized benefit is enhanced regulation of offspring's thermal environment. The developmental thermal environment during development can be optimized behaviorally through nest site selection and brooding, and it can be further enhanced by physiological heat production. In fact, enhancement of the developmental thermal environment has been proposed as the initial driving force for the evolution of endothermy in bird and mammals. I used pythons (Squamata: Pythonidae) to expand existing knowledge of behavioral and physiological parental tactics used to regulate offspring thermal environment. I first demonstrated that brooding behavior in the Children's python (Antaresia childreni) is largely driven by internal mechanisms, similar to solitary birds, suggesting that the early evolution of the parent-offspring association was probably hormonally driven. Two species of python are known to be facultatively thermogenic (i.e., are endothermic during reproduction). I expand current knowledge of thermogenesis in Burmese pythons (Python molurus) by demonstrating that females use their own body temperature to modulate thermogenesis. Although pythons are commonly cited as thermogenic, the actual extent of thermogenesis within the family Pythonidae is unknown. Thus, I assessed the thermogenic capability of five previously unstudied species of python to aid in understanding phylogenetic, morphological, and distributional influences on thermogenesis in pythons. Results suggest that facultative thermogenesis is likely rare among pythons. To understand why it is rare, I used an artificial model to demonstrate that energetic costs to the female likely outweigh thermal benefits to the clutch in species that do not inhabit cooler latitudes or lack large energy reserves. In combination with other studies, these results show that facultative thermogenesis during brooding in pythons likely requires particular ecological and physiological factors for its evolution.
ContributorsBrashears, Jake (Author) / DeNardo, Dale (Thesis advisor) / Harrison, Jon (Committee member) / Deviche, Pierre (Committee member) / McGraw, Kevin (Committee member) / Smith, Andrew (Committee member) / Arizona State University (Publisher)
Created2012
Description
A global warming of two degrees Celsius is predicted to drive almost half the world's lizard populations to extinction. Currently, the Phoenix metropolitan region in Arizona, USA, is an average of 3 oC warmer than the surrounding desert. Using a bare lot as a control, I placed copper lizard models with data loggers in several vegetation and irrigation treatments that represent the dominant backyard landscaping styles in Phoenix (grassy mesic with mist irrigation, drip irrigated xeric, unirrigated native, and a hybrid style known as oasis). Lizard activity time in summer is currently restricted to a few hours in un-irrigated native desert landscaping, while heavily irrigated grass and shade trees allow for continual activity during even the hottest days. Maintaining the existing diversity of landscaping styles (as part of an ongoing mitigation strategy targeted at humans) will be beneficial for lizards.
Fourteen native lizard species inhabit the desert surrounding Phoenix, AZ, USA, but only two species persist within heavily developed areas. This pattern is best explained by a combination of socioeconomic status, land cover, and location. Lizard diversity is highest in affluent areas and lizard abundance is greatest near large patches of open desert. The percentage of building cover has a strong negative impact on both diversity and abundance. Despite Phoenix's intense urban heat island effect, which strongly constrains the potential activity and microhabitat use of lizards in summer, thermal patterns have not yet impacted their distribution and relative abundance at larger scales.
Fourteen native lizard species inhabit the desert surrounding Phoenix, AZ, USA, but only two species persist within heavily developed areas. This pattern is best explained by a combination of socioeconomic status, land cover, and location. Lizard diversity is highest in affluent areas and lizard abundance is greatest near large patches of open desert. The percentage of building cover has a strong negative impact on both diversity and abundance. Despite Phoenix's intense urban heat island effect, which strongly constrains the potential activity and microhabitat use of lizards in summer, thermal patterns have not yet impacted their distribution and relative abundance at larger scales.
ContributorsAckley, Jeffrey (Author) / Wu, Jianguo (Thesis advisor) / Sullivan, Brian (Thesis advisor) / Myint, Soe (Committee member) / DeNardo, Dale (Committee member) / Angilletta Jr., Michael (Committee member) / Arizona State University (Publisher)
Created2015
Description
The purpose of this creative thesis project was to create a line of veterinary educational materials (VEMs) for the target population of English Second Language (ESL) Spanish Speakers. Target population research and personal veterinary clinic experience resulted in the selection of five topics for consideration, these were: vaccination, surgical sterilization, feline leukemia, canine parvovirus, and euthanasia. The two formats chosen for subject matter presentation was a line of Spanish brochures as a physical resource for clients and a line of newsletters in both English and Spanish for online viewing purposes. The overarching objectives during the creation of the VEMs were to encourage communication between veterinary staff and clients while increasing client education and compliance. During design formatting emphasis was placed on creating a line of VEMs that would be consistent, concise, and modern in order to achieve maximum client interest. The completed line of VEMs successfully fulfilled the overarching objectives of encouraging communication, increasing client education, and increasing client compliance to ultimately increase patient care.
ContributorsHammer, Jessica Nicole (Author) / DeNardo, Dale (Thesis director) / Rosales, Jesus (Committee member) / Howard, Jennifer (Committee member) / Barrett, The Honors College (Contributor) / School of International Letters and Cultures (Contributor) / School of Life Sciences (Contributor)
Created2015-05
Description
Water-balance is a critical but understudied consideration for animals reproducing in dry environments, as females invest a significant amount of water into their offspring. What makes water especially challenging, is that few animals are known to have true water storage, whereas energy as fat storage is well-documented. Recent studies have suggested the possibility that, when drinking water is scarce, animals can catabolize their muscles, thereby extracting cellular water. In this study, the aim was to show this as a potential method used by animals reproducing in dry environments to cope with dehydration and still produce a clutch. Children's pythons (Antaresia childreni) were used to investigate this phenomenon due to the fact that they experience two, distinctive, reproductive phases- vitellogenesis (when protein and energy are mobilized and invested into the yolk) and gravidity (when the major water investment into the egg occurs, as well as egg shelling). Other factors that make them excellent candidates are that they are pure capital breeders (don't eat during the reproductive season) and can withstand periods of water deprivation that far outlast their reproductive gravid phase. Reproductive and non-reproductive females were deprived of water for the duration of gravidity, and their mass decrease, epaxial muscle shrinkage, blood osmolality, total protein, uric acid, triglycerides and ketones were measured at the onset of each reproductive stage; these values were compared to their water-provided counterparts. Water-deprived females experienced greater mass loss, epaxial muscle loss, blood plasma osmolality, and uric acid than water-provided females. These findings suggest that muscle catabolism is used as a method of dealing with water-deprivation during gravidity.
ContributorsKaminsky, Brittany Michele (Author) / DeNardo, Dale (Thesis director) / Angilletta, Michael (Committee member) / Brusch, George (Committee member) / School of Life Sciences (Contributor) / Department of English (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
Description
One way pathogen prevalence is maintained is by persistence within reservoir host species. Reservoir hosts are species that do not show any signs of disease when a pathogen infects them. As a result, the pathogen survives and is able to remain in the host population. Batrachochytrium dendrobatidis (Bd) is a chytrid fungus that has caused extensive amphibian declines. It has been suspected that reservoir hosts are a key to Bd remaining in certain amphibian populations. I studied dragonfly naiads (Anisoptera spp.), the aquatic life cycle stage immediately following hatching and preceding the emergence of wings, as potential reservoir hosts for Bd on the Mogollon Rim in Arizona. On the Mogollon Rim winter temperatures fall below the optimal thermal range for Bd. Boreal chorus frogs (Pseudacris maculata), the most common amphibian species on the Rim, maintain subzero body temperatures to survive the winter. Since the optimal thermal range for Bd is between 4°C and 25°C, it is unlikely that Bd can grow on the skin of these frogs during winter. As a result, it is unknown how Bd prevalence is maintained in the area. Recent studies showed that Bd can grow in non-amphibian hosts. I hypothesized that Bd could grow within the digestive tracts of dragonfly naiads, since they stay in the water and don’t maintain subzero body temperatures during the cold winters on the Rim. Non-native and native naiads were both included in this study; the non-native naiads were purchased from a company in California while the native naiads were captured from ponds on the Mogollon Rim. The digestive tracts of the naiads were then dissected, and the DNA was extracted using an animal tissue spin-column protocol. The extracted DNA was analyzed by qPCR. The qPCR analysis of the native and non-native dragonfly naiads revealed that the samples were either Bd-negative or very weakly Bd-positive, with most being the former. Based on these results, it does not appear that naiads are biologically significant reservoir hosts for Bd.
ContributorsAnigwe, Christopher (Author) / Collins, James (Thesis director) / DeNardo, Dale (Committee member) / Brus, Evan (Committee member) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
Description
There are numerous strategies for determining an organism's metabolic rate, one of which is the heart rate method. The heart rate method is based on a relationship between an organism's heart rate and its oxygen consumption (V(O2)). Although validations of the heart rate method have focused on adult animals, researchers could benefit from applying this method to embryonic animals. In this study, the heart rate's reliability as an indicator of oxygen consumption in early stage embryos of reptiles (or more specifically, lizards) is evaluated. The focus is primarily on the earliest stages of cardiovascular detection. The results suggest that while it may be possible to use a reliable heart rate method to find an accurate value for oxygen consumption of a group of early embryos in lizards if the oxygen pulse can be accurately identified, it is more likely that in the earliest stages of cardiovascular development, the heart rate cannot serve as a reliable indicator of V(O2) because it may not be the primary manner in which oxygen is distributed in Sceloporus undulatus.
ContributorsHambsch, Zakary Jordan (Author) / Angilletta, Michael (Thesis director) / DeNardo, Dale (Committee member) / Condon, Catriona (Committee member) / Barrett, The Honors College (Contributor) / School of Life Sciences (Contributor)
Created2013-05
Description
Attitudes toward animal welfare have been evolving in our society as we have developed from early agricultural roots to an increasingly urban and technologically advanced community. However, despite the growing societal appreciation and care for animals in our homes and backyards, veterinarians are still faced with cases of abuse and neglect. Although it may seem obvious for veterinarians, as animal welfare advocates, to confront this dilemma each time they are faced with it, that is not always the case. In order to assess the responsibilities of veterinarians in regard to neglect and abuse, an extensive literature review and analysis was performed and practicing veterinarians were interviewed to determine their attitudes regarding the responsibility to report suspected cases of animal neglect and abuse. Specifically, these interviews focused on such topics as the educational background of the practitioners, how empathy impacts their perception of animal welfare, their relationship with law enforcement agencies, and related questions. The study demonstrated that the most prominent factor in a veterinarian's understanding of violations of animal welfare stems from their educational background. Therefore, it is recommended that veterinary medicine programs alter their curricula to emphasize animal welfare training and the obligation of veterinarians to report suspected cases of neglect and abuse.
ContributorsMichael, Allison Therese (Author) / Minteer, Ben (Thesis director) / Ellison, Karin (Committee member) / DeNardo, Dale (Committee member) / Barrett, The Honors College (Contributor) / School of Life Sciences (Contributor)
Created2013-12
Description
This creative thesis project aimed to create career development resources that School of Life Sciences majors could use to enhance their college experience, expand the breadth of relevant career options for School of Life Sciences majors, and confront and divert career problems through the implementation of these career development resources. Students encounter career problems when their intention and action diverge. These career problems may cause a student to stop their pursuit of a given career, change majors, or even stop schooling completely. It is the objective of this project to help resolve these career problems by introducing a career development resource flyer that educates the student about a given career, provides coursework to guide a student towards this career path, familiarize students with extracurricular efforts necessary for this position, propose valuable resources that the student can utilize to learn more about the career, and offer a question and answer portion for further career and professional understanding. In order to create these career development resource flyers a variety of professionals, both with and without relationships with Arizona State University were contacted and interviewed. The answers gathered from these interviews were then utilized to create the career flyers. The project was successful in creating five distinct career development resource flyers, as well as a blank template with instructions to be used in the future by the School of Life Sciences. The career development resource flyers will be utilized by the School of Life Sciences advising staff for future exploratory majors, but is not limited to just these students. Aspirations are set to create an expansive reservoir of these resources for future generations of students to access in hopes that they will be better suited to find a career path that they are passionate about and be better prepared to attain.
ContributorsGallegos, Darius Sloan (Author) / Wilson Sayres, Melissa (Thesis director) / Downing, Virginia (Committee member) / DeNardo, Dale (Committee member) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2017-05