Electronic Theses and Dissertations

Date

2024

Document Type

Dissertation

Degree Name

Doctor of Philosophy

Department

Biology

Committee Chair

Emily Puckett

Committee Member

Amy Abell

Committee Member

Bernie Daigle

Committee Member

Duane McKenna

Committee Member

Jennifer Mandel

Abstract

Complex traits such as diet have shaped the evolutionary success of species, driving the diversity of form and function that we observe across the tree of life. My research investigates the genomic and macroevolutionary forces behind diet and other complex traits, revealing how they mediate evolutionary change across Mammalia. I utilized two complementary approaches for understanding the evolution of diet in mammals. First, I created two continuous dietary variables—degree of carnivory and degree of dietary specialization—to quantify the impact of diet on mammalian speciation. I found that degree of carnivory, rather than dietary specialization, significantly influenced speciation, but did not do so in all mammalian clades. This challenges previous understandings that dietary specialization shapes mammalian diversification. I then employed a comparative genomic approach to identify convergent signals of molecular evolution associated with the evolution of diet across mammals. I found that, as lineages became more herbivorous across the phylogeny, there was a convergent relaxation of molecular constraint acting on genes associated with liver and kidney functions. This relaxation represents reduced importance of these functions in herbivorous diets compared to more carnivorous feeding strategies. A unique aspect of the bear family, Ursidae, is the breadth of their dietary strategies, ranging from hyperherbivory to hypercarnivory. So, I conducted a genome-wide analysis of accelerated evolution in the family to understand shared aspects of evolution within this ecologically diverse clade. I linked bear-specific accelerated regions (BeARs) to biological functions such as visual perception, nervous system functioning, muscle development, and mRNA processing. Much of the accelerated genomic evolution that occurred in bears may be driven by the evolution of hibernation. Combined, my results deepen our understanding of the mechanisms by which complex traits evolve.

Comments

Data is provided by the student.

Library Comment

Dissertation or thesis originally submitted to ProQuest.

Notes

Open Access

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