ECOLOGY:
Hybrids Consummate Species Invasion
Wade Roush
BOULDER, COLORADO--When biologists think of the comings and goings of species, they often think of war--of new species invading and pushing out the old. In midwestern lakes, however, love seems to be the driving force. In lake after lake, an invading crayfish species is pushing local crayfish to extinction. But the invader itself is vanishing in the process, mating with the local crayfish to produce a new population of vigorous hybrids.