Year of Award

2024

Document Type

Dissertation

Degree Type

Doctor of Philosophy (PhD)

Degree Name

Ecology and Evolution

Department or School/College

Division of Biological Sciences

Committee Chair

Zachary A. Cheviron

Commitee Members

Jeffrey M. Good, H. Arthur Woods, Bret W. Tobalske, Kristi L. Montooth

Publisher

University of Montana

Abstract

The study of adaptation to extreme environments offers a lens to explore the fundamental processes of evolution. Organisms living in challenging conditions, such as high elevation, must evolve a suite of physiological and genetic adaptations to survive and thrive. However, our understanding of the mechanisms underlying such adaptations and the processes driving their evolution remains incomplete. This dissertation aims to expand our knowledge of adaptive evolution in extreme environments by integrating genomic, phenotypic, and demographic data in the North American deer mouse (Peromyscus maniculatus), a model system for high-altitude adaptation. The dissertation addresses three main gaps in knowledge: (1) the genetic determinants of survival at high altitude, (2) the temporal dynamics of selection on physiological phenotypes, and (3) the role of mitonuclear coevolution in high-altitude adaptation. Chapter 1 identifies novel candidate genes and pathways associated with survival in high-altitude deer mice by integrating genomic data with long-term mark-recapture data. Chapter 2 investigates the genetic basis and temporal dynamics of selection on aerobic performance and blood oxygen carrying capacity, revealing a temporal disconnect in the genetic and phenotypic determinants of fitness. Chapter 3 explores the role of mitonuclear coevolution, finding evidence for independent selection on mitochondrial and nuclear genes but no strong signatures of selection maintaining mitonuclear interactions or significant incompatibilities in admixed individuals. This dissertation highlights the importance of integrating diverse data types to gain a comprehensive understanding of adaptive evolution in extreme environments and may provide a valuable framework for future studies in diverse systems.

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