Transportation of species to areas outside their native ranges has been a feature of human culture for millennia. During this time such activities have largely been viewed as beneficial or inconsequential. However, it has become increasingly clear that human-caused introductions of alien biota are an ecological disruption whose consequences rival those of better-known insults like chemical pollution, habitat loss, and climate change. Indeed, the irreversible nature of most alien-species introductions makes them less prone to correction than many other ecological problems. Current reshuffling of species ranges is so great that the present era has been referred to by some as the “Homogocene” in an effort to reflect the.