Research Interests

My research has explored two of the evolutionary processes that have generated the extraordinary diversity of organisms: speciation and ecological divergence. My group has undertaken ecological, population genetic, and phylogenetic analyses of herbivorous insects and their host plants, which together account for nearly half the described species of organisms. Herbivorous insects exemplify ecological specialization and diversification, and coevolutionary responses of plants and insects to each other are postulated to have fostered diversification. My group was among the first to describe host-associated genetic variation in insect populations, and to use genetic variation to test for physiological tradeoffs that might account for ecological (i.e., host-plant) specialization. We have challenged claims for the prevalence of sympatric speciation by host-plant shifts, and were among the first to use coalescent analysis to test the hypothesis of founder-effect speciation in insects. I helped to clarify the meanings of "coevolution," and showed that despite frequent phylogenetic "conservatism" of insects' host associations, simultaneous divergence of plants and insects is unusual. We advanced the hypothesis that genetic changes in host preference may precede physiological adaptations, and have provided evidence that limitations on genetic variation may bias or constrain the avenues of adaptation, and thus influence phylogenetic patterns of ecological associations between plants and insects.

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Primary Section

Section 27: Evolutionary Biology

Secondary Section

Section 63: Environmental Sciences and Ecology