Abstract: Population genetic and genome sequence data are useful to understand processes of species divergence because they allow studying the roles played by gene flow and natural selection during this process and their consequences on patterns of genomic differentiation. I will describe studies of this type conducted in the classic species Drosophila pseudoobscura and its close relatives D. p. bogotana and D. persimilis. I will also describe gene expression work aimed at understanding the mechanisms of phenotypic differentiation between D. persimilis and D. pseudoobscura. A phenotype we have uncovered in hybrids of the two species may allow us making a connection between the divergence of these two species of Drosophila and their ecology. In the second part of the talk I will provide an overview of evolutionary genetic studies in the fig/fig wasp mutualism, focusing on population genetic studies of species divergence and studies of the effect of inbreeding on levels of population genetic variation.