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- All Subjects: thermal performance curve
- Creators: Angilletta, Michael
Description
I am evaluating a notion that stems from a controversial hypothesis of heat stress. The oxygen- and capacity-limited thermal tolerance (OCLTT) hypothesis predicts a positive correlation between the tolerance of hypoxia and the tolerance of heat in animals, where the notion claims that these animals must be metabolically active. To evaluate this notion, I tested heat coma recovery in several genetic lines of Drosophila melanogaster and compared it to data collected in prior studies. I hypothesized that the correlations between hypoxia tolerance and heat coma recovery would be similar to correlations found in Teague et al. (2017) and Fredette-Roman et al. (2020). After testing 65 lines from the Drosophila Genetic Reference Panel (DGRP), the notion was supported and provided evidence for the validity of OCLTT. Additional work is needed to enhance our understanding of the limitations of heat tolerance and doing such will generate more accurate models and predictions on how animals will respond to climate change.
ContributorsBabarinde, Oluwatosin Abimbola (Author) / Angilletta, Michael (Thesis director) / VandenBrooks, John (Committee member) / Youngblood, Jacob (Committee member) / School of Life Sciences (Contributor) / Department of Psychology (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
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