Elucidating the genetic basis of adaptation is one of the primary goals of evolutionary biology. I am using adaptation to dietary ethanol in Drosophila melanogaster, the common fruit fly, as a model system for studying the genetics of adaptation. Ethanol occurs naturally in the decaying fruits in which D. melanogaster breed, and natural populations in temperate regions have evolved high ethanol tolerance relative to ancestral tropical populations (and most other organisms!). By taking advantage of the many genetic resources available for D. melanogaster, my laboratory is identifying the genetic changes underlying the temperate tropical difference (e.g., Fry et al. 2008).
Other research interests, which I pursue mainly through theory and analysis of publicly available data, include the role of ecological divergence in speciation (e.g., Fry 2009) and the maintenance of genetic variation in life-history traits (e.g., Fry 2010).
For one approach to identifying genes involved in ethanol tolerance, we measured gene expression in replicate D. melanogaster populations that had been maintained on either ethanol-supplemented or normal medium for more than 300 generations (Yampolsky et al. 2012). From each population, RNA was isolated from newly hatched larvae that had been previously exposed, as embryos, to either plain water or an ethanol solution. As shown above, the ethanol pre-treatment dramatically increases ability of larvae to survive on ethanol-supplemented medium (Fry 2001). Using Affymetrix microarrays (see figure below), we identified ca. 100 genes that consistently differed in expression between ethanol-adapted and non-adapted populations, regardless of whether larvae came from ethanol- or water-treated embryos. Based on sequence and genetic mapping data, several of these genes are promising candidates for contributing to the temperate-tropical difference in ethanol tolerance. We are currently conducting experiments using mutants and other approaches to verify their roles in ethanol tolerance.