Date of Award:
8-2024
Document Type:
Dissertation
Degree Name:
Doctor of Philosophy (PhD)
Department:
Biology
Committee Chair(s)
Zachariah Gompert
Committee
Zachariah Gompert
Committee
Carol von Dohlen
Committee
Luis Gordillo
Committee
Paul Wolf
Committee
Karen Mock
Abstract
When Homo sapiens traveled out of Africa and interbred with the Neanderthals of Europe, human genes spread into the Neanderthal population. Likewise, genes from Neanderthals spread into the human genome—genes humans still carry to this day. The process whereby genetic material from one population is spread to another is known as gene flow. Gene flow—or the absence thereof—can have critical consequences for a population’s health and survival. On one hand, if no gene flow occurs, mating among close relatives can lead to high levels of inbreeding. Inbreeding can have devastating consequences for the health of populations, in some cases even leading to extinction. On the other extreme, gene flow between distantly-related populations or species can result in hybridization, also known as admixture. The evolutionary consequences of admixture vary widely. While some admixture events have negative consequences and result in an evolutionary dead end (i.e. crossing a horse and a donkey to produce a sterile mule), other admixture events improve population health and survival (i.e. when mixed-breed dogs show greater genetic health than their purebred parents, an outcome colloquially known as “hybrid vigor”). Understanding the varied effects of gene flow is critical to understanding evolution: patterns of gene flow can affect a population’s extinction risk, determine whether or not a population will successfully adapt to a changing environment, and can even alter how well we can predict evolutionary change. In this dissertation, I explored how inbreeding, environmental stress, barriers to gene flow, and admixture affect evolutionary outcomes and conservation risk in insects. Specifically, I showed that (1) the combination of heat stress and a poor food source interact non-additively to increase the severity of inbreeding depression in seed beetles (Callosobruchus maculatus), (2) barriers to gene flow (i.e. rivers, mountains) have shaped patterns of genetic structure and genetic health in the endemic Hayden’s ringlet butterfly (Coenonympha haydenii), and (3) admixture among populations of seed beetles alters both their ability to survive and adapt to a novel, poor food source and our ability to predict evolutionary change at a genomic level.
Checksum
b75be8512b39ee70edfb5570e34f50b3
Recommended Citation
Springer, Amy L., "From Inbreeding to Admixture: How the Diverse Consequences of Gene Flow Shape Evolutionary Dynamics and Population Viability" (2024). All Graduate Theses and Dissertations, Fall 2023 to Present. 259.
https://digitalcommons.usu.edu/etd2023/259
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