Genetic diversity and the tempo and mode of ecological adaptation
Thomas H.Q. Powell, Binghamton University
Speciation occurs when previously interbreeding populations evolve genetic barriers to gene flow. This is the process that is ultimately responsible for generating the biodiversity in our ecosystems. However, the idea that ecology might be a major player in speciation has only recently gained widespread acceptance. The term ecological speciation refers to the evolution of reproductive isolation due to divergent natural selection on ecological traits. While several strong examples of ecological speciation have been documented, there are still considerable theoretical constraints on ecology’s ability to drive speciation. In this talk, I am going to discuss some of my work in a classic ecological speciation system, the incipient speciation of the apple maggot fly, Rhagoletis pomonella, during recent historical times. I am specifically going to use this work to address one important constraint on ecological divergence: the source of genetic variation. The sort of traits that are the most likely drive ecological speciation are much more likely to evolve divergently from standing genetic variation than through the accumulation of novel mutations. But why should populations harbor genetic variation for some future adaptation? My seminar is going to focus on how the Rhagoletis system sheds some light on the ecological and biogeographic scenarios that might promote the kind of genetic diversity that can fuel complex ecological adaptation and speciation.
About the speaker
My research is broadly focused on understanding the origin and maintenance of biodiversity. I am particularly interested in the role of ecological adaptation in the formation of new species and the role of on-going evolutionary processes in the response of ecological communities to global change. For more information, visit www.powellevolab.com.
Photo (above): Dr. Thomas Powell, Assistant Professor of Biological Sciences; BS, Shepherd University and PhD, University of Notre Dame.