Collaborative Research: Mating Signals and Demographic Divergence: Species Comparisons and Experimental Tests

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Lay SummaryCocroft, Hunt and WoodMating signals can diverge early in the process of speciation, but it is unclear whether signal divergence plays a direct role in speciation or is a byproduct of other processes such as ecological specialization. Our goal is to determine the role of mating signals in the diversification of a group of plant-feeding insects. The Enchenopa binotata species complex of treehoppers consists of nine species that are specialists on various trees and shrubs in North America. Considerable evidence suggests that speciation in this group occurred as a result of a series of shifts to novel host plants. A host shift alters life history timing, which, in combination with high host fidelity, allows divergence in traits that enhance performance on a novel host. Our research will test the hypothesis that divergence in mating signals is important in speciation by reducing gene flow between populations on ancestral and novel host plants. Our project will integrate (1) a comparative study of vibrational mating signals in the nine extant Enchenopa binotata species; (2) comparison of patterns of signal variation within and among species with patterns of DNA sequence divergence; and (3) determination of whether divergence in signals and life history traits has occurred in experimentally host-shifted populations. This research will provide a complementary picture of the relationship between mating signals and divergence not only in fully differentiated species, but also in lineages in the early stages of host plant race formation. Results of this research will enhance our basic understanding of speciation, and may provide practical benefits such as an improved understanding of how agricultural pests become established on novel host species.