Book excerpt: Through the work included in this dissertation, I have sought to explore the evolutionary processes that generate and maintain adaptive biodiversity in two focal systems. First, I reviewed new insights based on genomic analyses of a classic system, Darwin's finches, and connected these findings to the growing literature on adaptive introgression and its contributions to phenotypic evolution (Chapter 1). I then looked to another classic system in evolutionary biology with a long tradition of theoretical and empirical research: polymorphic wing pattern mimicry in Papilio swallowtail butterflies. In Papilio, I studied i) natural selection on polymorphic wing pattern phenotypes in the field (Chapter 2), and ii) the genetic basis and evolution of convergent polymorphic wing pattern mimicry (Chapter 3).