Work in our lab is centered on understanding the processes and mechanisms that have led to the evolution of new species and to the generation of genetic diversity in two study systems: species of the Drosophila pseudoobscura group, and the fig/fig-wasp mutualism. Common problems that we have been addressing in the two research systems are: What are the roles played by hybridization and introgression during the evolution of new species? What are the consequences of those processes on genetic variation at a genomic scale? Additional studies we are conducting with Drosophila are focused on using whole-genome expression arrays to identify genetic changes underlying phenotypic differences between closely related species, including genetic changes involved in regulatory hybrid dysfunction (gene expression changes affecting fertility or viability). Additional studies in the fig/fig-wasp mutualism are centered on understanding the causes and consequences of incongruent cophylogenetic patterns of divergence of closely related Neotropical figs and their pollinators, studying the geographical context of species diversification in the mutualism, and studying the population genetic consequences of evolution in subdivided populations. We use a combination of genomic, population genetic, and phylogenetic approaches to address all those questions. In addition to our main work on those two systems, we have returned to our previous work on the evolution of the human parasite Trypanosoma cruzi.