RUI Collaborative Research: CHEMOSENSORY BASIS OF HOST SELECTION BY ANT-ASSOCIATED BUTTERFLIES. Ann M. Fraser (Kalamazoo College) and John E. Hofferberth (Kenyon College). How new species arise is an enduring question in biology. The study of host selection behavior in herbivorous insects has provided important insights by demonstrating that shifts in host preference can evolve rapidly and that local adaptation to novel hosts can initiate genetic divergence and thus play an important role in the early stages of the speciation process. Underlying host specificity and host shifts are complex chemosensory mechanisms that mediate behavioral responses to host stimuli. Elucidating these mechanisms and their role in ecological specialization and reproductive isolation, therefore, is important to our understanding of the speciation process. Building on studies of herbivorous insects and their association with plants, this project seeks to understand how obligate association with ants may enhance diversification in the butterfly family Lycaenidae. Using the Australian butterfly genus Jalmenus and their attendant Iridomyrmex ants as a model, this collaborative research project aims to elucidate the olfactory cues used by butterflies to locate and identify appropriate ant partners, and to characterize the degree to which butterfly populations exhibit local adaptation with respect to host ant selection. To elucidate the olfactory cues, butterfly antennae will be screened for electrophysiological responses to volatile components emitted by ants. Electrophysiologically-active compounds will be chemically synthesized to verify identifications and then tested for behavioral activity using attraction and egg-laying bioassays. Electrophysiological and behavioral studies will be conducted in Fraser's laboratory at Kalamazoo College and in Australia. Chemical syntheses and identifications will be carried out in Hofferberth's laboratory at Kenyon College. The results of this research will broaden our understanding of how host recognition mechanisms and host selection behavior influence the speciation process in taxa that have close associations with other species. This project will provide undergraduate students with research opportunities that integrate biological and chemical approaches to address broad evolutionary questions, and teach skills that are useful for basic and applied research. This project will also provide the PIs with an opportunity to engage in multidisciplinary research and to establish collaborations with international researchers in Australia.
