PARENT SESSION
Symposium 20: Exotic Species: A Source of Insight into Ecology, Evolution and Biogeography.
Organized by: DF Sax, JJ Stachowicz, and SD Gaines
Thursday, August 5, 1:30 PM to 5:00 PM, Oregon Ballroom 203.

Invasive species as an opportunity to study the rate, predictability, and processes of rapid evolution.

Huey, Raymond^*,, Gilchrist, George,

ABSTRACT- Invasive species are usually treated as an ecological problem. However, invasive species are subject to the forces of evolution in new environment; and sometimes they evolve with remarkable rapidity. Such changes potentially affect the ecological dynamics involving invasive versus native species. We focus on rapid evolutionary shifts taking place in a species of fruit fly (Drosophila subobscura) that is native to Europe, but that invaded the West Coast of North and also South America in the late '70s. It spread over broad geographic areas, and is now the most common drosophilid in cooler areas. We are working with colleagues at the University of Barcelona to study the rates and predictability of evolution of these flies on a continental scale. Observed evolutionary rates of some traits are among the fastest ever recorded, and geographic clines are forming in several traits that have direct ecological relevance. Our findings reinforce the view that invasive species are an evolutionary as well as an ecological problem.

Key words: Drosophila subobscura, invasive