Evolution and diversification of mutualism and parasitism between leafflower moths and their host plants


Raymond Building R3-048, 21111 Lakeshore Road, St Anne de Bellevue, QC, H9X 3V9, CA

Special seminar by David Hembry, PhD, Department of Entomology, Cornell University

Understanding the role of species interactions in the generation and maintenance of insect diversity across spatial and temporal scales is a central goal of insect systematics and of evolutionary ecology generally. Here, I explore the longstanding hypothesis that mutualism acts as a constraint in evolution using interactions between brood pollinating leafflower moths and their host leafflower plants. First, I use an insular co-radiation of pollinating leafflower moths and leafflower trees on oceanic islands in the South Pacific to show that despite extremely high species-specificity, these brood pollination interactions can be highly dynamic and labile over evolutionary timescales and may not diversify via cospeciation. Second, I show how this mutualism has repeatedly broken down into parasitism—in fact, more so than any known mutualism examined to date. I further demonstrate that the transition to parasitism has permitted gains in ecological opportunity for some parasitic lineages. These results suggest that mutualism may function as a constraint at certain macroevolutionary scales, while not constraining hostshifts and colonization of remote islands over shorter evolutionary timescales. Furthermore, these studies demonstrate how we can use phylogenetic approaches, in tandem with other methods, to study the role of interactions between insects and other organisms in generating insect biodiversity.