James D. Fry

Associate Professor

Contact Information:

University of Rochester
Department of Biology
River Campus Box 270211
Rochester, New York 14627-0211

Hutchison 318

585-275-7835

James D. Fry

Research Overview


Elucidating the genetic basis of adaptation is one of the primary goals of evolutionary biology. Three unresolved questions are the number of genes involved in adaptations, the relative contributions of changes in protein structure and changes in gene expression to phenotypic change, and the extent to which independent occurrences of the same adaptation in different populations or species share a similar genetic basis. My lab is 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 independently evolved high ethanol tolerance relative to ancestral tropical populations. By taking advantage of the powerful genetic tools available for D. melanogaster, we are attempting to identify the genetic changes responsible for the temperate-tropical difference. We have found evidence that multiple gene expression changes and a structural alteration in the enzyme aldehyde dehydrogenase contribute to the difference. Interestingly, the latter enzyme is also responsible for variation in ethanol tolerance among human populations.

In other projects, we are investigating the rates and evolutionary implications of deleterious mutations, and the role of ecological divergence in speciation. These projects are being pursued primarily through theoretical modeling and analyses of publicly available datasets, although new experiments are planned.

melanogaster

For one approach to identifying genes involved in ethanol tolerance in Drosophila, we are taking advantage of the inducibility of ethanol tolerance in larvae. As shown above, larvae hatching from eggs that developed in contact with ethanol have much higher survival on ethanol-supplemented medium than larvae hatching from eggs exposed only to water (Fry 2001). We isolated RNA from ethanol-exposed and control larvae and compared gene expression using Affymetrix GeneChip© microarrays, which contain synthetic oligonucleotides from almost all 14,000 Drosophila genes (see figure below). This procedure identified many genes upregulated by ethanol, some of which likely contribute to the increased tolerance of larvae from ethanol-treated eggs. We are investigating whether some of these ethanol-inducible genes show higher baseline (non-induced) expression in more ethanol-tolerant populations than in less tolerant populations. Such genes would be strong candidates for being involved in the genetic difference in tolerance between populations.

Expression

Selected Publications