Humans, it seems, are not the only species to seek refuge fromcrowded, competitive environments. Given the opportunity, plants and animals move in droves to relatively impoverished habitats that have been virtually cleared of natural rivals, according to a recent paper published in the weekly scientific journal Science. The article by UC Davis geology professor Geerat J. Vermeij, a paleontologist who specialists in molluscs, may help scientists predict the future of a habitat if resident species become extinct or if historical barriers break down. "As environments around the world are being disturbed and as species are being exploited and eliminated on an ever-increasing scale, this phenomenon of geographical release is likely to become more common," Vermeij said. Large-scale extinctions of species can turn a biota (the flora and fauna of a region) into a sort of biological vacuum that is especially prone to invasions. As evidence for his hypothesis, Vermeij has synthesized 20 years of biotic interchange research covering the past 25 million years. In the case of a sea-level Panama Canal, Vermeij argues that more species would invade from the eastern Pacific to the more biologically impoverished and less biologically sophisticated western Atlantic.