Evil Invaders Investigated

It sounds like the makings of an ecological disaster: an epidemic of invasive species that wipes out the delicate native species in its path. But a paper published in The Proceedings of the National Academy of Sciences points out that not all invasions have led to mass extinctions. 

Dov Sax, an ecologist at Brown University, and Steven D. Gaines, a marine biologist at the University of California Santa Barbara, are at odds with many other experts on invasive species. Their critics argue that the speed with which species are being moved around the planet, combined with other kinds of stress on the environment, is having a major impact. There is little doubt that some invasive species have driven native species extinct. But Dr. Sax argues that they are far more likely to be predators than competitors. While some invasions are indeed devastating, they often do not set off extinctions. They can even spur the evolution of new diversity.

September 9, 2008 New York Times http://www.nytimes.com/2008/09/09/science/09inva.html