Climate-induced range overlap among closely related species

Contemporary climate change is causing large shifts in biotic distributions 1 , which has the potential to bring previously isolated, closely related species into contact 2 . This has led to concern that hybridization and competition could threaten species persistence 3 . Here, we use bioclimatic models to show that future range overlap by the end of the century is predicted for only 6.4% of isolated, congeneric species pairs of New World birds, mammals and amphibians. Projected rates of climate-induced overlap are higher for birds (11.6%) than for mammals (4.4%) or amphibians (3.6%). As many species will have difficulty tracking shifting climates 4 , actual rates of future overlap are likely to be far lower, suggesting that hybridization and competition impacts may be relatively modest.