Hybridization has been of major importance for plant evolution. Recent research has shown that hybrid plant resistance to herbivores may differ from resistance of pure parental plants to herbivores. Hybrids could be more, less, equally, or intermediately resistant compared to parental species. Determining if one of these patterns is prevalent could contribute to understanding important ecological and evolutionary aspects of plant-herbivore interactions, as well as the role of hybrids in considering issues of biological diversity. This project focuses on willow species and their hybrids that co-occur in the same habitat. The two parent willow species have different chemical systems in their leaves that can be studied in the hybrids and parents. The PI has developed molecular genetic markers to characterize naturally occurring and crossed hybrids and parental species. The PI will analyze the relationships between hybridization, chemical variation and herbivore resistance for field plants, and cloned and seedling plants in a common garden. He will test if differences in chemical expression are correlated with herbivore resistance of hybrids, and will use molecular markers to determine the frequency of hybridization in several communities that have both willow species.
