Once again, "conventional wisdom" ain't necessarily so...

Friendly Invaders

Exotic species receive lots of attention and create lots of worry. Some scientists consider biological invasions among the top two or three forces driving species into extinction. But Dr. Sax, Dr. Gaines and several other researchers argue that attitudes about exotic species are too simplistic. While some invasions are indeed devastating, they often do not set off extinctions. They can even spur the evolution of new diversity.

“I hate the ‘exotics are evil’ bit, because it’s so unscientific,” Dr. Sax said.

Dr. Sax and his colleagues 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.