Date of Award:

2016

Document Type:

Thesis

Degree Name:

Doctor of Philosophy (PhD)

Department:

Biology

Advisor/Chair:

Susannah S. French

Abstract

Organisms must be able to cope with many natural and anthropogenic stressors in order to successfully survive and reproduce. These stressors can come in many forms and are increasing as anthropogenic activities become more and more prevalent across the globe. In order to cope with these stressors, organisms must allocate limited energy away from processes such as reproduction to mount a stress response. This stress response involves the activation of the hypothalamic-pituitary-adrenal axis and results in a cascade of hormones and down-stream effects, such as changes in reproduction and immune function. In order to understand how reptiles and amphibians cope with a variety of stressors, I conducted seven experiments. I first validated an immune assay which can be employed across vertebrate taxa and can measure functional immune responses. I then analyzed effects of natural stressors (wounding, predator attacks, natural toxins, and food restriction) and/or anthropogenic stressors (restraint and the anthropogenic toxins polybrominated diphenyl ether and indoxacarb) on reptiles and/or amphibians. In measuring many different stressors and several different taxa (the side blotched-lizard, Uta stansburiana, the rough-skinned newt, Taricha granulosa, the wandering gartersnake, Thamnophis elegans, and the common gartersnake, T. sirtalis), I hoped to determine if patterns in energy allocation and trade-offs existed on a broad scale. I found that while there are some similarities among the responses, each organism exposed to different stressors had to be examined separately. This supports the emerging consensus that the stress response is extremely context-dependent and responses seen in one context cannot be inferred to other organisms with disparate life-histories, sexes, geographic range, or previous experience. Because of this, researchers must focus on the population in question to assess physiological questions before making management decisions.

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