Collaborative Research: Host-Associated Genetic Differentiation in the Goldenrod Elliptical-Gall Moth Gnorimoschema Gallaesolidaginis - Parallel Host Race Formation?

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0107938NasonThe astounding diversity of herbivorous insects (1-5 million species) is poorly understood, but one possible mechanism for their diversification is sympatric speciation via host race formation - that is, adaptation to and speciation on different host plants in the absence of geographic barriers to gene exchange. While a few cases of host race formation in sympatry are known, it remains un-known whether this process is rare and special or frequent and predictable. A promising avenue toward answering this question is provided by the diverse group of insects attacking the goldenrods Solidago altissima and S. gigantea. Focussing on one of these insects, the goldenrod elliptical-gall moth, Gnorimoschema gallaesolidaginis, we will use genetic data to document the geographic extent and structure of genetic differentiation, reconstruct the history of host shifting, and identify evolutionary forces driving differentiation. At the same time, we will use lab and field experiments to identify ecological mechanisms maintaining host plant affiliation and reproductive isolation (e.g. mate choice, adult and larval host choice, and/or host-associated tradeoffs in larval performance). Our studies of differentiation in G. gallaesolidaginis will complement ongoing studies of differentiation in other Solidago herbivores. Together, these studies will tell us much about how (and how often) host race formation might have contributed to the spectacular diversification of herbivorous insects.