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Though it is a widespread adaptation in humans and many other animals, parental care comes in a variety of forms and its subtle physiological costs, benefits, and tradeoffs related to offspring are often unknown. Thus, I studied the hydric, respiratory, thermal, and fitness dynamics of maternal egg-brooding behavior in Children's

Though it is a widespread adaptation in humans and many other animals, parental care comes in a variety of forms and its subtle physiological costs, benefits, and tradeoffs related to offspring are often unknown. Thus, I studied the hydric, respiratory, thermal, and fitness dynamics of maternal egg-brooding behavior in Children's pythons (Antaresia childreni). I demonstrated that tight coiling detrimentally creates a hypoxic developmental environment that is alleviated by periodic postural adjustments. Alternatively, maternal postural adjustments detrimentally elevate rates of egg water loss relative to tight coiling. Despite ventilating postural adjustments, the developmental environment becomes increasingly hypoxic near the end of incubation, which reduces embryonic metabolism. I further demonstrated that brooding-induced hypoxia detrimentally affects offspring size, performance, locomotion, and behavior. Thus, parental care in A. childreni comes at a cost to offspring due to intra-offspring tradeoffs (i.e., those that reflect competing offspring needs, such as water balance and respiration). Next, I showed that, despite being unable to intrinsically produce body heat, A. childreni adjust egg-brooding behavior in response to shifts in nest temperature, which enhances egg temperature (e.g., reduced tight coiling during nest warming facilitated beneficial heat transfer to eggs). Last, I demonstrated that A. childreni adaptively adjust their egg-brooding behaviors due to an interaction between nest temperature and humidity. Specifically, females' behavioral response to nest warming was eliminated during low nest humidity. In combination with other studies, these results show that female pythons sense environmental temperature and humidity and utilize this information at multiple time points (i.e., during gravidity [egg bearing], at oviposition [egg laying], and during egg brooding) to enhance the developmental environment of their offspring. This research demonstrates that maternal behaviors that are simple and subtle, yet easily quantifiable, can balance several critical developmental variables (i.e., thermoregulation, water balance, and respiration).
ContributorsStahlschmidt, Zachary R (Author) / DeNardo, Dale F (Thesis advisor) / Harrison, Jon (Committee member) / McGraw, Kevin (Committee member) / Rutowski, Ronald (Committee member) / Walsberg, Glenn (Committee member) / Arizona State University (Publisher)
Created2011
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Description
We examined the evolutionary morphological responses of Drosophila melanogaster that had evolved at constant cold (16°), constant hot (25°C), and fluctuating (16° and 25°C). Flies that were exposed to the constant low mean temperature developed larger thorax, wing, and cell sizes than those exposed to constant high mean temperatures. Males

We examined the evolutionary morphological responses of Drosophila melanogaster that had evolved at constant cold (16°), constant hot (25°C), and fluctuating (16° and 25°C). Flies that were exposed to the constant low mean temperature developed larger thorax, wing, and cell sizes than those exposed to constant high mean temperatures. Males and females both responded similarly to thermal treatments in average wing and cell size. The resulting cell area for a given wing size in thermal fluctuating populations remains unclear and remains a subject for future research.
ContributorsAdrian, Gregory John (Author) / Angilletta, Michael (Thesis director) / Harrison, Jon (Committee member) / Rusch, Travis (Committee member) / Barrett, The Honors College (Contributor) / School of Life Sciences (Contributor)
Created2015-05
Description
Speciation is the fundamental process that has generated the vast diversity of life on earth. The hallmark of speciation is the evolution of barriers to gene flow. These barriers may reduce gene flow either by keeping incipient species from hybridizing at all (pre-zygotic), or by reducing the fitness of hybrids

Speciation is the fundamental process that has generated the vast diversity of life on earth. The hallmark of speciation is the evolution of barriers to gene flow. These barriers may reduce gene flow either by keeping incipient species from hybridizing at all (pre-zygotic), or by reducing the fitness of hybrids (post-zygotic). To understand the genetic architecture of these barriers and how they evolve, I studied a genus of wasps that exhibits barriers to gene flow that act both pre- and post-zygotically. Nasonia is a genus of four species of parasitoid wasps that can be hybridized in the laboratory. When two of these species, N. vitripennis and N. giraulti are mated, their offspring suffer, depending on the generation and cross examined, up to 80% mortality during larval development due to incompatible genic interactions between their nuclear and mitochondrial genomes. These species also exhibit pre-zygotic isolation, meaning they are more likely to mate with their own species when given the choice. I examined these two species and their hybrids to determine the genetic and physiological bases of both speciation mechanisms and to understand the evolutionary forces leading to them. I present results that indicate that the oxidative phosphorylation (OXPHOS) pathway, an essential pathway that is responsible for mitochondrial energy generation, is impaired in hybrids of these two species. These results indicate that this impairment is due to the unique evolutionary dynamics of the combined nuclear and mitochondrial origin of this pathway. I also present results showing that, as larvae, these hybrids experience retarded growth linked to the previously observed mortality and I explore possible physiological mechanisms for this. Finally, I show that the pre-mating isolation is due to a change in a single pheromone component in N. vitripennis males, that this change is under simple genetic control, and that it evolved neutrally before being co-opted as a species recognition signal. These results are an important addition to our overall understanding of the mechanisms of speciation and showcase Nasonia as an emerging model for the study of the genetics of speciation.
ContributorsGibson, Joshua D (Author) / Gadau, Jürgen (Thesis advisor) / Harrison, Jon (Committee member) / Pratt, Stephen (Committee member) / Verrelli, Brian (Committee member) / Willis, Wayne (Committee member) / Arizona State University (Publisher)
Created2013
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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

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
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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
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Description
This study illustrates the abilities of the honeybee, Apis mellifera, to learn and differentiate between patterns solely off their spatial frequencies. Patterns were chosen based off of calculations derived from the measurements of the physical construction of the apposition compound eye, which led to predictions of what the bees could

This study illustrates the abilities of the honeybee, Apis mellifera, to learn and differentiate between patterns solely off their spatial frequencies. Patterns were chosen based off of calculations derived from the measurements of the physical construction of the apposition compound eye, which led to predictions of what the bees could theoretically see. The hypothesis was then that bees would have a visual threshold where patterns with spatial frequencies that fall below this line should be easily distinguishable, and patterns above the threshold would have scores that mimic if the bees made choices randomly. There were 9 patterns tested, all with different spatial frequencies and in the colors of black, white, and gray. The bees were tested on their learning and pattern differentiation abilities with 10 pattern comparisons, with the lower frequency of the two being associated with an unscented sucrose solution reward. The results were surprising in that the previous studies pointing towards this visual threshold were inaccurate because of some of the patterns being learning in an intermediate ability. These intermediate scores suggest that the calculations predicting what the bees could see clearly were slightly wrong because it was more likely that the bees saw those images in more of a blur, which resulted in their intermediate score. Honeybees have served as a useful model organisms over the decades with studying learning involving visual information. This study lacked in its total numbers of trials and bees tested, which could have led to incomplete results, and this showing of an intermediate score and ability. Future studies should continue in order to advance this understanding of a perceptually and cognitively advance processing animal.
ContributorsBalsino, Brandon Bartholomew (Author) / Harrison, Jon (Thesis director) / Smith, Brian (Committee member) / Duell, Meghan (Committee member) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2015-12
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Description
Parabasalia is a phylum of flagellated protists with a large range of cell sizes, spanning from as little as 7 µm in length (e.g. Pentatrichomonas hominis) to well over 300 µm (e.g. Pseudotrichonympha grassii). Many Parabasalia are associated with animals in mutualistic, parasitic, or commensal relationships. The largest

Parabasalia is a phylum of flagellated protists with a large range of cell sizes, spanning from as little as 7 µm in length (e.g. Pentatrichomonas hominis) to well over 300 µm (e.g. Pseudotrichonympha grassii). Many Parabasalia are associated with animals in mutualistic, parasitic, or commensal relationships. The largest Parabasalia species are obligate mutualists of termites, which help to digest lignocellulose. While the specific digestive roles of different protist species are mostly unknown, Parabasalia with different cell sizes are known to inhabit different regions of the termite hindgut. It is currently unclear whether these size differences are driven by selection or drift, but it is well known that cell size correlates with genome size in eukaryotes. Therefore, in order to gain insight into possible selection pressures or mechanisms for cell size increase, genome sizes were estimated for the five Parabasalia species that inhabit the hindgut of Coptotermes formosanus Shiraki. The cell volumes and C-values for the five protist species are 89,190 µm3 and 147 pg in Pseudotrichonympha grassii, 26,679 µm3 and 56 pg in Holomastigotoides hartmanni, 8,985 µm3 and 29 pg in Holomastigotoides minor, 1,996 µm3 and 12 pg in Cononympha leidyi , and 386 µm3 and 6 pg in Cononympha koidzumii. The positive correlation between genome size and cell size was maintained in this group (R2 = 0.76). These genome sizes are much larger than the previously estimated genome sizes of non-termite associated Parabasalia, which spanned 2-fold ranging from 0.088 pg (in Tetratrichomonas gallinarum) to 0.181 pg (in Trichomonas foetus). With these new estimates, the range now spans over 1,500-fold from 0.088 pg to 147 pg in P. grassii, implying potential differences in the level of selective pressures for genome size in termite-associated Parabasalia compared to other protists.
ContributorsMontoya, Samantha (Author) / Gile, Gillian (Thesis advisor) / Wideman, Jeremy (Committee member) / Chouvenc, Thomas (Committee member) / Arizona State University (Publisher)
Created2021
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Understanding why animals form social groups is a fundamental aim of sociobiology. To date, the field has been dominated by studies of kin groups, which have emphasized indirect fitness benefits as key drivers of grouping among relatives. Nevertheless, many animal groups are comprised of unrelated individuals. These cases provide unique

Understanding why animals form social groups is a fundamental aim of sociobiology. To date, the field has been dominated by studies of kin groups, which have emphasized indirect fitness benefits as key drivers of grouping among relatives. Nevertheless, many animal groups are comprised of unrelated individuals. These cases provide unique opportunities to illuminate drivers of social evolution beyond indirect fitness, especially ecological factors. This dissertation combines behavioral, physiological, and ecological approaches to explore the conditions that favor group formation among non-kin, using as a model the facultatively social carpenter bee, Xylocopa sonorina. Using behavioral and genetic techniques, I found that nestmates in this species are often unrelated, and that non-kin groups form following extensive inter-nest migration.Group living may arise as a strategy to mitigate constraints on available breeding space. To test the hypothesis that nest construction is prohibitively costly for carpenter bees, I measured metabolic rates of excavating bees and used imaging techniques to quantify nest volumes. From these measurements, I found that nest construction is highly energetically costly, and that bees who inherit nests through social queuing experience substantial energetic savings. These costs are exacerbated by limitations on the reuse of existing nests. Using repeated CT scans of nesting logs, I examined changes in nest architecture over time and found that repeatedly inherited tunnels become indefensible to intruders, and are subsequently abandoned. Together, these factors underlie intense competition over available breeding space. The imaging analysis of nesting logs additionally revealed strong seasonal effects on social strategy, with social nesting dominating during winter. To test the hypothesis that winter social nesting arises from intrinsic physiological advantages of grouping, I experimentally manipulated social strategy in overwintering bees. I found that social bees conserve heat and body mass better than solitary bees, suggesting fitness benefits to grouping in cold, resource-scarce conditions. Together, these results suggest that grouping in X. sonorina arises from dynamic strategies to maximize direct fitness in response to harsh and/or competitive conditions. These studies provide empirical insights into the ecological conditions that favor non-kin grouping, and emphasize the importance of ecology in shaping sociality at its evolutionary origins.
ContributorsOstwald, Madeleine (Author) / Fewell, Jennifer H (Thesis advisor) / Amdam, Gro (Committee member) / Harrison, Jon (Committee member) / Pratt, Stephen (Committee member) / Kapheim, Karen (Committee member) / Arizona State University (Publisher)
Created2022
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Predatory bacteria are a guild of heterotrophs that feed directly on other living bacteria. They belong to several bacterial lineages that evolved this mode of life independently and occur in many microbiomes and environments. Current knowledge of predatory bacteria is based on culture studies and simple detection in natural systems.

Predatory bacteria are a guild of heterotrophs that feed directly on other living bacteria. They belong to several bacterial lineages that evolved this mode of life independently and occur in many microbiomes and environments. Current knowledge of predatory bacteria is based on culture studies and simple detection in natural systems. The ecological consequences of their activity, unlike those of other populational loss factors like viral infection or grazing by protists, are yet to be assessed. During large-scale cultivation of biological soil crusts intended for arid soil rehabilitation, episodes of catastrophic failure were observed in cyanobacterial growth that could be ascribed to the action of an unknown predatory bacterium using bioassays. This predatory bacterium was also present in natural biocrust communities, where it formed clearings (plaques) up to 9 cm in diameter that were visible to the naked eye. Enrichment cultivation and purification by cell-sorting were used to obtain co-cultures of the predator with its cyanobacterial prey, as well as to identify and characterize it genomically, physiologically and ultrastructurally. A Bacteroidetes bacterium, unrelated to any known isolate at the family level, it is endobiotic, non-motile, obligately predatory, displays a complex life cycle and very unusual ultrastructure. Extracellular propagules are small (0.8-1.0 µm) Gram-negative cocci with internal two-membrane-bound compartmentalization. These gain entry to the prey likely using a suite of hydrolytic enzymes, localizing to the cyanobacterial cytoplasm, where growth begins into non-compartmentalized pseudofilaments that undergo secretion of vesicles and simultaneous multiple division to yield new propagules. I formally describe it as Candidatus Cyanoraptor togatus, hereafter Cyanoraptor. Its prey range is restricted to biocrust-forming, filamentous, non-heterocystous, gliding, bundle-making cyanobacteria. Molecular meta-analyses showed its worldwide distribution in biocrusts. Biogeochemical analyses of Cyanoraptor plaques revealed that it causes a complete loss of primary productivity, and significant decreases in other biocrusts properties such as water-retention and dust-trapping capacity. Extensive field surveys in the US Southwest revealed its ubiquity and its dispersal-limited, aggregated spatial distribution and incidence. Overall, its activity reduces biocrust productivity by 10% at the ecosystem scale. My research points to predatory bacteria as a significant, but overlooked, ecological force in shaping soil microbiomes.
ContributorsBethany Rakes, Julie Ann (Author) / Garcia-Pichel, Ferran (Thesis advisor) / Gile, Gillian (Committee member) / Cao, Huansheng (Committee member) / Jacobs, Bertram (Committee member) / Arizona State University (Publisher)
Created2022
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Description
To combat the global antimalarial resistance crisis effective resistance management strategies are needed. To do so, I need to gain a better understanding of the ecological interactions occurring within malaria infections. Despite the importance of the complex interplay among co-infecting strains, our current knowledge and empirical data of within-host diversity

To combat the global antimalarial resistance crisis effective resistance management strategies are needed. To do so, I need to gain a better understanding of the ecological interactions occurring within malaria infections. Despite the importance of the complex interplay among co-infecting strains, our current knowledge and empirical data of within-host diversity and malaria disease dynamics is limited. In this thesis, I explore the multifaceted dynamics of malaria infections through an ecological lens. My overall research question is: "How do ecological interactions, including niche complementarity, competition dynamics, and the cost of resistance, shape the outcomes of malaria infections, and what implications does this have on understanding and improving resistance management strategies?” In Chapter II, titled “Niche Complementarity in Malaria Infections” I demonstrate that ecological principles are observed in malarial infections by experimentally manipulating the biodiversity of rodent malaria P. chabaudi infections. I observed that some parasites experienced competitive suppression, others experienced competitive facilitation, while others were not impacted. Next, in Chapter III, titled “Determining the Differential Impact of Competition Between Genetically Distinct Plasmodium falciparum Strains” I investigate the differential effect of competition among six genetically distinct strains. The impact of competition varied between strain combinations, and both suppression and facilitation were observed, but most pairings had no competitive interactions. Lastly, in Chapter IV, titled “Assessing Fitness Costs in Malaria Parasites: A Comprehensive Review and Implications for Drug Resistance Management”, I summarize where the field currently stands and what evidence there is for the presence of a fitness cost, or lack thereof, and I highlight the current gaps in knowledge. I found that evidence from field, in vitro, and animal models are overall suggestive of the presence of a fitness cost, however, these costs were not always found. Amid the current focus on malaria eradication, it is crucial to understand the impact of biodiversity on disease severity. By incorporating an ecological approach to infectious disease systems, I can gain insights on within-host interactions and how they impact parasite fitness and transmissibility.
ContributorsSegovia, Xyonane (Author) / Huijben, Silvie (Thesis advisor) / Bean, Heather (Committee member) / Gile, Gillian (Committee member) / Hogue, Ian (Committee member) / Lake, Douglas (Committee member) / Arizona State University (Publisher)
Created2024