Ecological and Evolutionary Context of the Stress Response in Larvcal Anurans

Show simple item record Middlemis Maher, Jessica E. en_US 2011-09-15T17:14:00Z NO_RESTRICTION en_US 2011-09-15T17:14:00Z 2011 en_US en_US
dc.description.abstract Describing and understanding the interactions between environment and phenotype, and the resulting consequences for populations and communities, is a central goal of ecological and evolutionary research and theory. In vertebrates, the endocrine stress response provides a mechanistic connection between environmental variation and organism phenotype, with resulting effects on fitness. Using larval anurans as a model system, I combine field surveys, mesocosm experiments, and exogenous hormone manipulation to explore the complex interactions among the predator stress response, phenotype, and fitness, with respect to other contemporary stressors and species evolutionary history. First, I developed a comprehensive understanding of the predator stress response over time, mapping hormone production to changes in behavior and morphology, and demonstrating the effects on predation survival. I found that tadpoles modulate their predator stress response to maximize survival under predation risk, and additionally showed that the stress hormones produced during a predator response initiates morphological changes indistinguishable from predator-induced morphology. Next, I used a comparative approach to place the predator stress response into an evolutionary context, testing the hypothesis that species that predictably encounter high larval predator densities reduce the costs of chronic endocrine activation. Across four anuran species arrayed in conspecific pairs, I found support for this hypothesis, showing that species typically under high predation risk reduce the magnitude of their stress response to predator presence relative to conspecifics. I next considered the combined effects of inbreeding and predator presence, and showed that inbred tadpoles also elevate stress hormone production, although there is no additive effect in combination with predator presence. The resulting behavioral and morphological changes in inbred tadpoles may place them at a disadvantage under some circumstances. Finally, I showed that reduced food resource availability also increases stress hormone production independently of predator presence. Together, these results connect perceived predation risk, endocrine response, and phenotypic plasticity and place them in an ecological and evolutionary context. Furthermore, this research highlights the importance of using an integrative approach to investigate the impacts of developmental history on organism-environment interactions. en_US
dc.language.iso en_US en_US
dc.subject Tadpole Predator Stress en_US
dc.title Ecological and Evolutionary Context of the Stress Response in Larvcal Anurans en_US
dc.type Thesis en_US
dc.description.thesisdegreename Ph.D. en_US
dc.description.thesisdegreediscipline Ecology and Evolutionary Biology en_US
dc.description.thesisdegreegrantor University of Michigan, Horace H. Rackham School of Graduate Studies en_US
dc.contributor.committeemember Werner, Earl E. en_US
dc.contributor.committeemember Denver, Robert J. en_US
dc.contributor.committeemember Low, Bobbi S. en_US
dc.contributor.committeemember Tibbetts, Elizabeth en_US
dc.subject.hlbsecondlevel Ecology and Evolutionary Biology en_US
dc.subject.hlbtoplevel Science en_US
dc.owningcollname Dissertations and Theses (Ph.D. and Master's)
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