9629822 Raymond B. Huey and George W. Gilchrist Human activities have led to an alarming increase in the number of species introduced into new areas. Evolutionary changes in introduced species have received little attention, although such changes may influence the persistence and impact of introduced species. The fly Drosophila subobscura provides an opportunity for studying evolutionary rates in response to new environments. This species is broadly distributed in Europe. In the late 70's it was accidentally introduced into both North and South America. It rapidly colonized broad geographic areas with very different climates, and is now the most common Drosophila in some areas. This project will investigate how temperature, a key climate factor, influences the fitness of flies from climatically distinct populations in Europe, the evolutionary "baseline", and from similar ones in North America. The amount of differentiation among the North American populations, relative to the European ones, will indicate whether introduced insects may be able to evolve rapidly in nature. This project is important for understanding what limits the distribution, spread, and persistence of introduced pests, as well as understanding the effects of introduced species on native species and ecosystems.
