Date of Award

Spring 2017

Project Type

Dissertation

Program or Major

Genetics

Degree Name

Doctor of Philosophy

First Advisor

Matthew D MacManes

Second Advisor

David Plachetzki

Third Advisor

Philip Hatcher

Abstract

Research elucidating the genetic architecture of physiological mechanisms enabling survival and reproduction in extreme environments is becoming prominent in evolutionary biology. The desert, in particular, poses numerous challenges for its endemic species, and mammals (and often, rodents) have been the focus for survival adaptations pertaining to water-limitation. However, desert rodent adaptation research has focused predominantly on survival, while potential physiological reproductive adaptations to dehydration have received less attention, aside from research evaluating water as reproductive cue. The fact that we do not know the physiological mechanisms enabling reproduction during dehydration is surprising, as desert rodents must possess adaptations to successfully reproduce in their water-limited habitats. The cactus mouse (Peromyscus eremicus), a desert-specialist in the Southwest United States, is the focus of my genetic exploration of reproductive adaptations to dehydration. My dissertation describes three research studies that 1) characterize male cactus mouse reproductive tissue transcriptomes and find signatures of positive selection in these tissues relative to other rodent species, 2) describe differential expression of genes responding to water-limitation within testes, providing candidate genes for future studies exploring the impacts of acute and chronic drought on P. eremicus reproduction, and 3) generate a seminal vesicle proteome representative of proteins present in hydrated and dehydrated conditions experienced by the cactus mouse. These three studies contribute comprehensive genetic data critical to future research exploring the effects of water-limitation on reproduction as well as the genetic mechanisms for potential male reproductive adaptations in this desert-adapted rodent. Research on desert adaptations is particularly timely, as climate change will result in more frequent stochastic drought events and elevated temperatures. These increasing abiotic shifts will exacerbate clinical challenges for global health; thus, an enhanced understanding of mammalian desert-specialist adaptations may improve our ability to address these physiological demands in humans.

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