<p>The problem is two fold: how does natural selection operate on systems of interacting genes and how does natural selection operate in natural populations. To address the first problem, I have conducted a theoretical investigation into the evolution of control and the distribution of mutations in a simple system of interacting genes, a linear metabolic pathway. I found that control is distributed unevenly between enzymes, with upstream enzymes possessing the greatest control and accumulating the most beneficial mutations during adaptive evolution. To address the second problem, I investigated the evolution of copper tolerance in the common yellow monkeyflower, Mimulus guttatus. I genetically mapped a major locus controlling copper tolerance, Tol1. A Dobzhansky-Muller incompatibility was hypothesized to also be controlled by Tol1, however, we have demonstrated that it maps to another, tightly linked locus, Nec1. Finally, we investigated the parallel evolution of copper tolerance in multiple new discovered mine populations. We found that copper tolerance has evolved in parallel multiple times via at least two distinct physiological mechanisms. In four mine populations, there was a strong signal of selection at markers linked to Tol1, implying that copper tolerance has evolved via the same genetic mechanisms in these populations.</p> / Dissertation

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