Gregory K. Davis
Assistant Professor, Department of Biology, Bryn Mawr College, Bryn Mawr, PA 19010
At Bryn Mawr College my undergraduate students and I study environmentally cued, discrete, alternate phenotypes exhibited by the pea aphid, Acyrthosiphon pisum. The remarkable developmental plasticity of this insect presents an opportunity to examine divergent developmental processes that are somehow directed by a single genome and cued by the environment. Our focus is the reproductive polyphenism, in which differences in day length determine whether mothers will produce daughters that reproduce either sexually by laying fertilized eggs, or asexually by allowing oocytes to complete embryogenesis within the mother without fertilization. Oocytes and embryos that are produced asexually and develop within the mother develop more rapidly, are yolk-free, and much smaller than oocytes and embryos that are produced sexually. I am interested in two general questions, both of which concern developmental differences between the sexual and asexual morphs and their means of reproducing: 1) What is the nature of the molecular switch that specifies sexual versus asexual fate during embryonic development?, and 2) How have the molecular mechanisms of pattern formation adapted to the dramatically modified version of embryogenesis that occurs within asexual mothers? As an investigator working with an emerging model system, I am sensitive to technical obstacles in such work and hope I can assist EDEN in achieving its goal of helping labs to overcome such obstacles.