Creative Destruction of Mass Extinctions as Illustrated by Frogs

It suggests that the mass extinction event at the end of the Cretaceous—largely caused by an asteroid striking the Earth—also wiped out most of the frog species that were alive then, leaving behind only a few survivors. With many other species also wiped out, the slate was wiped clean. There were many new ecological niches that the remaining frogs could spread into. That provided a kind of evolutionary rocket fuel for their rapid diversification.

“We know that the mass extinction event wiped out most of the dinosaurs, except for a few bird species, which then exploded in diversity and became one of the dominant groups of land animals,” says David Hillis, professor of integrative biology at UT Austin and co-author of a paper appearing this week in the journal Proceedings of the National Academy of Sciences. “As we look at more and more groups of life, we see the same pattern, and that turns out to be the case for frogs as well.”

The research reinforces earlier findings, also by UT Austin scientists, that provide heft to the argument that mass extinction events can lead to unusual spurts of evolutionary activity.

The new paper’s corresponding authors are David Cannatella at UT Austin, David Wake of the University of California, Berkeley, and Peng Zhang of Sun Yat-Sen University. Other authors include Yan-Jie Feng and Dan Liang of Sun Yat-Sen; and David Blackburn of the Florida Museum of Natural History.

The researchers gathered genetic samples from 156 frog species and combined it with previously published data on 145 more species to build the most complete frog family tree yet. In the new samples, they studied variations in 95 genes—compared with past studies that used only 5 to 12 genes—to get a much higher-resolution view of how individual species relate to one another.

Today, there are more than 6,700 known frog species, representing 55 families and living in a wide range of habitats from trees to aquatic environments to underground. This study significantly tightens the time frame in which this diversity came about.

Support for the research was provided by the U.S. National Science Foundation, the National Natural Science Foundation of China and the National Youth Talent Support Program and National Science Fund for Excellent Young Scholars of China.Contacts and sources:
Christine Sinatra
University of Texas at Austin