Genetic interactions : epistasis, linkage and speciation




Dagilis, Andrius Jonas

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Population genetics often makes simplifying assumptions regarding the interactions between genes. Interactions between genes, whether through epistasis or linkage effects, vastly increase the complexity of mathematical modeling, and often require data that has not historically been available. In this Dissertation, I present three chapters that use this complexity as a basis to explain empirical patters in evolution. In the first chapter, I show that inversions may become associated with assortative mating by linking assortative mating loci to loci that impact fitness directly. Such inversions have been observed between sympatric species pairs, implicating them in the process of speciation. In the second chapter, I develop a model of speciation predicated on epistatic interactions building up within populations as well as between them as they diverge. The model makes novel predictions about the rate of speciation under varying circumstances. Certain parts of the genome are expected to contribute more heavily to hybrid fitness, including the sex chromosomes. In the third chapter, I analyze phased sex chromosomes of a fish with young sex chromosomes, identifying potential targets of sexually antagonistic selection - a form of selection in which an allele maybe deleterious in one sex but beneficial in the other. Together, these chapters capitalize on the role that genetic interactions play in determining the course and cause of speciation and evolution of genome structure.


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