Unwitting humans assist lizard invasions across the Caribbean
For centuries, Caribbean anole lizards have been homebodies. Species have tended to stick to the islands where they evolved, because sailing across the vast distances of ocean separating them isn’t exactly easy for most land dwellers. As a result, geographically isolated islands tend to have fewer species overall, whereas less isolated islands usually boast more. But now scientists think this accepted ecological wisdom may need to be revised, and it’s all humans’ fault. When researchers studied the present-day distribution of anole lizard species across the Caribbean, they found that an island’s geographic isolation no longer necessarily corresponded to fewer species. Instead, it was all about its economic isolation within the global trade network. That’s because, like many species, anole lizards have started hitching rides on cargo ships, making it much easier for them to reach far-flung islands. The more trade an island participates in, the more species diversity it tends to have, no matter its geographic location, the team reports online today in Nature. The flip side is that economic isolation might protect native lizard species from newly imported competitors. Cuba, for example, would rapidly gain 1.65 lizard species if the United States lifted its trade embargo, the researchers predict.