Ph.D Duke University, 1990
408A Manter Hall
I am an evolutionary ecologist -- I study both the ecological factors that cause natural selection and the genetic basis of ecologically important traits. Using manipulative field experiments and quantitative genetic methods, I hope to understand constraints on response to natural selection. Together with my graduate students and collaborators at other universities I am involved in three ongoing projects.
1) Evolution of response to herbivory in wild sunflower, Helianthus annuus. In response to insect damage plant populations may evolve either resistance (characters that reduce the amount of damage) or tolerance (characters that reduce the impact of damage on plant fitness). However, tolerance, and constraints on the joint evolution of resistance and tolerance, are relatively poorly understood. Using quantitative genetic methods we are evaluating predictions of theoretical models, as well as describing mechanisms of tolerance of insect damage.
2) Evolutionary and ecological consequences of the escape of transgenes into wild populations. Because commercial sunflower is host to a number of economically important insect pests, several seed companies are developing transgenic varieties. Wild Helianthus annuus and commercial sunflower are the same species and are completely interfertile. Thus, if transgenic varieties are released commercially it is likely that the transgenes will escape (via pollen flow to wild plants) into wild populations. We are examining the fitness effects of a Bt transgene in a wild background, as well as the potential effects of this transgene on sunflower population dynamics and insect community structure within sunflower heads.
3) Evolution of the sex ratio, mating system, and sexual dimorphism in Croton texensis, an annual in the Euphorbiaceae. Croton is dioecious (but rare hermaphrodites occur), it has a sex ratio that fluctuates among years from female to male biased, and it is sexually dimorphic for several morphological characters. For these reasons Croton is ideally suited for examining the evolution of plant mating systems.