9322795 D'Antonio The widespread occurrence of biological invasions offers the opportunity to study changes in the dynamics and genetics of populations and the ecological effects of those changes. Such changes are important in light of the increasing mixing and homogenization of the world's species and habitats. This study will address the evolutionary and ecological importance of genetic changes resulting from hybridization between two closely related plant species which have recently come into contact as a result of human activity. Carpobrotus edulis is an aggressive South African perennial introduced into California in the early 1900's where it invades coastal dune, grassland and scrub habitats. Carpobrotus chilensis is a less aggressive species that was common throughout California before the introduction of C. edulis. It exhibits little competitive pressure on native dune species. In this study, the investigators will combine genetic techniques and field experiments to establish the extent to which hybridization is occurring between these species and examine the effect of hybridization and introgression on morphological, ecological and fitness characteristics important to successful establishment and invasion. Also, some of the community-level consequences of hybridization will be identified. %%% The historical separation of these species provides the ideal system in which to measure gene flow and corresponding changes in fitness and ecological adaptation. The results of this study will contribute to understanding the impact of hybridization on the genetic integrity of native species and the conservation of native ecosystems.
