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- All Subjects: Biology
- Creators: Angilletta, Michael
Description
Ephemeral and intermittent streams are valuable sources of surface water support in the arid ecosystems of the Southwestern United States. These streams account for over 80% of the streams in the American Southwest and their importance has been indicated in many studies. Ephemeral and intermittent streams support a wide range of plant and animal species in both continuous and episodic fashions. This study aimed to gain a better understanding of the relationship between streamflow permanence and patterns of biomass and secondary production of the riparian fauna these ecosystems support. This was accomplished through a yearlong survey in the Huachuca Mountains of Southeastern, Arizona where macroinvertebrates were collected at various sites along a gradient of streamflow permanence before, during, and after the three month monsoon season that supplies most of the annual rainfall in this region. The results of my surveys indicate that 1) Sites characterized by low streamflow permanence were more responsive to changes in precipitation than sites characterized by relatively high streamflow permanence 2) In ephemeral streams, there is a significant peak in terrestrial macroinvertebrate production and biomass both during and after the monsoon season 3) streamflow permanence may convey consistent but not exceptional secondary production whereas seasonality in rainfall may convey exceptional but episodic secondary production—more so in sites where streamflow is not consistent.
ContributorsMcCartin, Michael Patrick (Author) / Sabo, John (Thesis director) / Stromberg, Juliet (Committee member) / Barrett, The Honors College (Contributor) / School of Life Sciences (Contributor)
Created2014-05
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 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
Studies of animal contests often focus solely on a single static measurement of fighting ability, such as the size or the strength of the individual. However, recent studies have highlighted the importance of individual variation in the dynamic behaviors used during a fight, such as, assessment strategies, decision making, and fine motor control, as being strong predictors of the outcome of aggression. Here, I combined morphological and behavioral data to discover how these features interact during aggressing interactions in male virile crayfish, Faxonius virilis. I predicted that individual variation in behavioral skill for decision making (i.e., number of strikes thrown), would determine the outcome of contest success in addition to morphological measurements (e.g. body size, relative claw size). To evaluate this prediction, I filmed staged territorial interactions between male F. virilis and later analyzed trial behaviors (e.g. strike, pinches, and bout time) and aggressive outcomes. I found very little support for skill to predict win/loss outcome in trials. Instead, I found that larger crayfish engaged in aggression for longer compared to smaller crayfish, but that larger crayfish did not engage in a greater number of claw strikes or pinches when controlling for encounter duration. Future studies should continue to investigate the role of skill, by using finer-scale techniques such as 3D tracking software, which could track advanced measurements (e.g. speed, angle, and movement efficiency). Such studies would provide a more comprehensive understanding of the relative influence of fighting skill technique on territorial contests.
ContributorsNguyen, Phillip Huy (Author) / Angilletta, Michael (Thesis director) / McGraw, Kevin (Committee member) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
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
The southwestern willow flycatcher (Empidonax traillii extimus) is listed as an endangered species throughout its range in the southwestern United States. Little is known about its sub-population spatial structure and how this impacts its population viability. In conjunction with being listed as endangered, a recovery plan was produced by the US Fish and Wildlife Service, with recovery units (sub-populations) roughly based on major river drainages. In the interest of examining this configuration of sub-populations and their impact on the measured population viability, I applied a multivariate auto-regressive state-space model to a spatially extensive time series of abundance data for the southwestern willow flycatcher over the period spanning 1995-2010 estimating critical growth parameters, correlation in environmental stochasticity or "synchronicity" between sub-populations (recovery units) and extinction risk of the sub-populations and the whole. The model estimates two parameters, the mean and variance of annual growth rate. Of the models I tested, I found the strongest support for a population model in which three of the recovery units were grouped (the Lower Colorado, Gila Basin, and Rio Grande recovery units) while keeping all others separate. This configuration has 6.6 times more support for the observed data than a configuration assigning each recovery unit to a separate sub-population, which is how they are circumscribed in the recovery plan. Given the best model, the mean growth rate is -0.0234 (CI95 -0.0939, 0.0412) with a variance of 0.0597 (CI95 0.0115, 0.1134). This growth rate is not significantly different from zero and this is reflected in the low potential for quasi-extinction. The cumulative probability of the population experiencing at least an 80% decline from current levels within 15 years for some sub-populations were much higher (range: 0.129-0.396 for an 80% decline). These results suggest that the rangewide population has a low risk of extinction in the next 15 years and that the formal recovery units specified by the original recovery plan do not correspond to proper sub-population units as defined by population synchrony.
ContributorsDockens, Patrick E. T. (Author) / Sabo, John (Thesis advisor) / Stromberg, Juliet (Committee member) / Fenichel, Eli (Committee member) / Arizona State University (Publisher)
Created2012
Description
Three populations of experimentally evolved Drosophila melanogaster populations made up of high temperature (H, constant 25 ᵒC), low temperature (C, constant 16 ᵒC) and temporal homogeneity (T, environment changes between 16 ᵒC and 25 ᵒC) were prepared and assayed to determine difference in citrate synthase activity. Between the three groups, the results were inconclusive: the resulting reaction rates in units of nmol min-1mgfly-1 were 81.8 + 20.6, 101 + 15.6, and 96.9 + 25.2 for the hot (H), cold (C), and temporally homogeneous (T) groups, respectively. We conclude that the high associated variability was due to a lack of control regarding the collection time of the experimentally evolved Drosophila.
ContributorsBelohlavek, David (Author) / Angilletta, Michael (Thesis director) / Francisco, Wilson (Committee member) / Barrett, The Honors College (Contributor) / Department of Chemistry and Biochemistry (Contributor)
Created2015-05
Description
I am evaluating the genomic basis of a model of heat tolerance in which organisms succumb to warming when their demand for oxygen exceeds their supply. This model predicts that tolerance of hypoxia should correlate genetically with tolerance of heat. To evaluate this prediction, I tested heat and hypoxia tolerance in several genetic lines of Drosophila melanogaster. I hypothesized that genotypes that can fly better at high temperatures are also able to fly well at hypoxia. Genotypes from the Drosophila Genetic Reference Panel (DGRP) were assessed for flight at hypoxia and normal temperature (12% O2 and 25°C) as well as normoxia and high temperature (21% O2 and 39°C). After testing 66 lines from the DGRP, the oxygen- and capacity-limited thermal tolerance theory is supported; hypoxia-resistant lines are more likely to be heat-resistant. This supports previous research, which suggested an interaction between the tolerance of the two environmental variables. I used this data to perform a genome-wide association study to find specific single-nucleotide polymorphisms associated with heat tolerance and hypoxia tolerance but found no specific genomic markers. Understanding factors that limit an organism’s stress tolerance as well as the regions of the genome that dictate this phenotype should enable us to predict how organisms may respond to the growing threat of climate change.
ContributorsFredette-Roman, Jacob Daniel (Author) / Angilletta, Michael (Thesis director) / VandenBrooks, John (Committee member) / Youngblood, Jacob (Committee member) / School of Life Sciences (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
Ectotherms rely on external heat to attain target body temperatures which can vary based on the animal’s current physiological activity. Many ectotherms become thermophilic (“heat-loving”) during crucial physiological processes like digestion and reproduction, behaviorally thermoregulating to increase body temperature higher than what they otherwise prefer. However, there is a positive relationship between body temperature and water loss that dictates increasing body temperature typically elicits an increase in water loss. Animals that inhabit areas where water is at least seasonally limited (e.g., deserts, wet-dry forests) may face a tradeoff between prioritizing behavioral thermophily to optimize physiological processes versus prioritizing water balance and potentially sacrificing some aspect of total performance capability.It is thus far unknown how reduced water availability and subsequent dehydration may influence thermophily in ectotherms. I hypothesized that behaviorally thermoregulating ectotherms exhibit thermophily during critical physiological events, and the extent to which thermophily is expressed is influenced by the animal’s hydric state. Using Children’s pythons (Antaresia childreni), I investigated the effects of dehydration on behavioral thermophily during digestion and reproduction. I found that dehydration caused a suppression in digestion-associated thermophily, where dehydrated snakes returned to pre-feeding body temperature sooner than they did when they were hydrated. In contrast, water deprivation at different reproductive stages had no effect on thermophily despite leading to a significant increase in the female’s plasma osmolality.
ii
Additionally, the timing of water deprivation during reproduction had differing effects on plasma osmolality and circulating triglyceride, total protein, and corticosterone concentrations. My research provides evidence of the sensitive and complex dynamic between body temperature, water balance, and physiological processes. At a time when many dry ecosystems are becoming hotter and drier, my investigation of dehydration and its influence on thermal dynamics and physiological metrics provides insight into cryptic effects on the vital processes of digestion and reproduction.
ContributorsAzzolini, Jill L. (Author) / Denardo, Dale F. (Thesis advisor) / John-Alder, Henry (Committee member) / Angilletta, Michael (Committee member) / Pratt, Stephen (Committee member) / Arizona State University (Publisher)
Created2023
Description
Introduction: Often it is presumed that in high-income countries, like the United States, water insecurity is not an issue. Yet, more than 2 million individuals in the United States are affected by water insecurity. Experiencing the effects of water insecurity are informal settlements and impoverished communities termed as “colonias”, characterized by the lack of possessing basic infrastructures and services, including water systems and wastewater disposal amongst many. Purpose: To critically analyze how water insecurity manifests in the colonias and the impacts it has on the health and well-being of the community members.
Methods: An extensive systematic literature review was conducted in the effort to bring a meaningful framework of existing challenges and potential resolutions and theorize water insecurity in colonias.
Results: The effects of water insecurity due to water scarcity and water contamination in the colonias led to health complications, unsanitary living conditions and mental distress for residents. The causes of water insecurity in the colonias were because of political exclusion, municipal underbounding and the failure to monitor water quality.
Conclusion: The dire consequences of household water insecurity to an individual, no less an entire population, are detrimental to health and well-being. Despite this acknowledgement of a critical and basic human necessity, literature reveals a robust water governance infrastructure is much needed for the people in colonias. For meaningful progress and developments to be made in addressing water insecurity for the people of colonias, this review was approached through a transdisciplinary lens - one that achieves convergence.
ContributorsPatwoary, Nargish (Author) / Wutich, Amber (Thesis advisor) / Sabo, John (Thesis advisor) / Roque, Anais (Committee member) / Arizona State University (Publisher)
Created2021
Description
The migratory grasshopper (Melanoplus sanguinipes) is one of the most economically important grasshoppers in the western rangelands of the United States (US), capable of causing incredible amounts of damage to crops and rangelands. While M. sanguinipes has been the focus of many research studies, areas like field nutritional physiology and ecology, and interactions between nutritional physiology and biopesticide resistance have very little research. This dissertation presents a multifaceted approach through three research-driven chapters that examine the nutritional physiology of M. sanguinipes and how it interacts with an entomopathogenic fungus for grasshopper management, as well as the challenges of using biopesticides for grasshopper management. Using the Geometric Framework for Nutrition (GFN), I established baseline macronutrient intake for M. sanguinipes, both in laboratory and field populations. Through this work, I found that field and lab populations can exhibit different protein (p) to carbohydrate (c) ratios, or Intake Targets (ITs), but that the field populations had ITs that matched the nutrients available in their environment. I also used the GFN to show that infections with the fungal entomopathogen Metarhizium robertsii DWR2009 did not alter ITs in M. sanguinipes. Although, when confined to carbohydrate- or protein-biased diets, infected grasshoppers had a slightly extended lifespan relative to grasshoppers fed balanced protein:carbohydrate diets. Interestingly, in a postmortem for the grasshopper, the fungus was only able to effectively sporulate on grasshoppers fed the 1p:1c diets, suggesting that grasshopper diet can have substantial impacts on the spread of fungal biopesticides throughout a population, in the absence of any inhibitory abiotic factors. Lastly, I examined the major barriers to fungal and microsporidian biopesticide usage in the United States, including low efficacy, thermal and environmental sensitivity, non-target effects, unregistered or restricted use, and economic or accessibility barriers. I also explored potential solutions to these challenges. This dissertation's focus on Melanoplus sanguinipes and Metarhizium roberstii Strain DWR2009, generates new information about how nutritional physiology and immunology intersect to impact M. sanguinipes performance. The methodology in each of the experimental chapters provides a framework for examining other problematic grasshopper species, by determining baseline nutritional physiology, and coupling nutrition with immunology to maximize the effectiveness of biological pesticides.
ContributorsZembrzuski, Deanna (Author) / Cease, Arianne (Thesis advisor) / Harrison, Jon (Committee member) / Angilletta, Michael (Committee member) / Jaronski, Stefan (Committee member) / Arizona State University (Publisher)
Created2023