The goal of this project is to determine if introduced plants have facilitated hybridization between two native herbivorous insect species. Putative hybrids of two butterfly species, the Great Copper and Edith's Copper, occur in two regions of California, where introduced plant species (Curly Dock and Sheep Sorrel) are present. The hybrid butterflies feed on these introduced plant species, whereas many populations of the parental species retain their associations with native host plants. This project will test the hypothesis that the introduced plant species are facilitating gene flow between two historically separate, genetically distinct insect species. Molecular marker analyses (DNA sequence and fingerprinting analyses), will allow detection of recent demographic events, such as population expansion and gene flow. Many, if not all, terrestrial ecosystems have been altered by human-caused biotic introductions. These introductions have resulted in numerous novel interactions, many of which have yet unknown outcomes. Native herbivorous insects using introduced plants offer an excellent system to explore the evolutionary and genetic responses of organisms to novel interactions. To date, there are no documented cases of hybridization between native insect species due to introduced plants. Such 'homogenization' of lineages could have profound effects on the genetic diversity of native organisms. This project will allow researchers to anticipate the future of evolution in light of novel interactions.
