"Treefrogs are a particularly important group to study for understanding amphibian diversity, because they can make up nearly half of all amphibian species in some rainforest sites," says lead author John J. Wiens, an Associate Professor in the Department of Ecology and Evolution at Stony Brook University. "Treefrogs also offer a striking example of the high local-scale biodiversity in the Amazon. At some sites in the Amazon rainforest, there are more treefrog species in a small area than there are across all of North America or Europe."

The researchers compiled data on the number of treefrog species at 123 sites around the world and analyzed the data with a new evolutionary tree (based on DNA sequence data) for 360 treefrog species. They discovered that the richness of treefrog species in the Amazon rainforest sites is not explained by wet, tropical climatic conditions alone.

"In fact, we found that many tropical rainforest sites that are outside the Amazon Basin have no more species than do some sites in temperate North America," explains Dr. Wiens.