Date of Award

Spring 2020

Document Type

Thesis

Terms of Use

© 2020 Stewart C. Silver. All rights reserved. This work is freely available courtesy of the author. It may only be used for non-commercial, educational, and research purposes. For all other uses, including reproduction and distribution, please contact the copyright holder.

Degree Name

Bachelor of Arts

Department

Biology

Abstract

Female mate choice and its effects on sexual selection have largely been considered with regard to sex steroids; however, an increasing body of literature suggests that glucocorticoids have important effects on female mate choice behavior. Females must balance current reproductive efforts against survival and future reproductive efforts, thereby incurring substantial tradeoffs while breeding. Glucocorticoid levels are elevated during the breeding season and are also produced in response to environmental stressors. To test the hypothesis that elevated glucocorticoids degrade female mate choice by interrupting the energetic demands required for reproduction, I assessed the impact of elevated corticosterone (CORT) on aspects of female mate choice in wild gray tree frogs (Hyla chrysoscelis). Those aspects consisted of proceptivity, preference for high pulse number, and choosiness. Female frogs were collected in amplexus and tested using two-choice phonotaxis assays. A thirty-minute rest period shortened approach latencies and injection per se appeared to weaken one measure of preference for high pulse number calls. However, elevated CORT levels did not impact either proceptivity or species-typical preferences, providing evidence that seasonal breeders are buffered against high concentrations of CORT that might jeopardize reproductive investment. On the other hand, a medium CORT dose significantly increased choosiness in females, though this effect was not seen with either higher or lower CORT doses. This suggests that CORT modulates energetic tradeoffs in a non-linear dose response fashion.

Included in

Biology Commons

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