Drosophila spp. have been used as empirical models for speciation, and for the evolution of mechanisms that maintain species identity when faced with the risk of hybridization. In a set of related projects, my postdoc Dr. Erin Myers and I are exploring the evolution and maintenance of the mechanisms that avoid hybridization when species co-occur. In the first project, we used Drosophila lineages collected from regions of species overlap but held in isolation for 50 years to explore the evolutionary fate of species isolating mechanisms when selection on species recognition has been relaxed for many generations. In the second project, we sought to identify the ecological and developmental factors that select against hybrids, and to quantify the pattern and intensity of their action across two generations of hybridization; this study revealed substantial, previously unknown costs of hybridization that should strongly favor enhanced species recognition in regions of sympatry. In the final experiment, we created artificial populations of potentially hybridizing species and placed them into experimental contact to observe the evolution of species recognition or isolating mechanisms in real time.
Myers, E. M., E. L. Joyce, T. Harwell, A. Lamb* and W. A. Frankino. Ecologically and developmentally imposed multi-generational costs of hybridization in sibling Drosophila species. in press at PLoS One
Myers EM, Frankino WA (2012) Time in a Bottle: The Evolutionary Fate of Species Discrimination in Sibling Drosophila Species. PLoS ONE 7(2): e31759. doi:10.1371/journal.pone.0031759