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How frogs flourished after dinosaurs croaked, reveals study

Frogs became most diverse vertebrates in the world, survived mass extinction some 66 mn years ago

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Frog (Photo : Wikipedia)
Frog (Photo : Wikipedia)

A massive asteroid strike that wiped out the millions of years ago created room for to colonize the Earth, said a today that shows how became among the most diverse vertebrates in the world. As many as 10 types of are believed to have survived the mass some 66 million years ago, which erased three-quarters of life on Earth, said the in the Proceedings of the National Academy of Sciences. Of these survivors, just three major kinds of went on to diversify and populate the planet.

Some 6,700 known exist today. Nearly nine in 10 -- 88 percent -- of modern can trace their roots back to these three lineages of hardy ancestors. "have been around for well over 200 million years, but this shows it wasn't until the of the that we had this burst of frog that resulted in the vast majority of we see today," said co-author David Blackburn, associate curator of amphibians and reptiles at the Florida Museum of Natural History. "This finding was totally unexpected." Until now, scientists believed that most modern emerged at a steady pace between 66 million and 150 million years ago. But the latest research shows burst onto the scene more like an "explosion," as the tiny amphibians swept into habitats left vacant by other creatures. For the study, researchers in and the United States compiled the largest set of frog genetic data ever evaluated. Genetic samples were taken from 156 and combined with previously published data on 145 more species. Past studies looked at five to 12 genes, while the current one examined variations in 95 genes, offering a much more detailed look at how individual species relate to one another. Researchers also studied fossil records to determine when different kinds of likely diverged from one another. Researchers found "evidence of not one but three explosions of new frog species, on different continents, and all concentrated in the aftermath of the mass die-off of most and many other species about 66 million years ago," said the Two of the three surviving lineages -- Microhylidae and Natatanura -- came out of Africa. The third, Hyloidea, spread throughout what became "These made it through on luck, perhaps because they were either underground or could stay underground for long periods of time," said co-author David Wake of the University of "This certainly draws renewed attention to the positive aspects of mass extinctions: They provide ecological opportunity for new things." Similar evolutionary events happened with birds, said co-author David Hillis, professor of integrative biology at University of Texas, Austin. "We know that the mass event wiped out most of the dinosaurs, except for a few bird species, which then exploded in and became one of the dominant groups of land animals," he said. "As we look at more and more groups of life, we see the same pattern, and that turns out to be the case for as well." In particular, the demise of and most birds created new niches for in the late Cretaceous Period. Some climbed into trees for shelter, leading to the evolution of the now ubiquitous tree "We think there were massive alterations of at that time, including widespread destruction of forests," said Blackburn. "But are pretty good at eking out a living in microhabitats, and as forests and tropical rebounded, they quickly took advantage of those new ecological opportunities." Some also adapted by producing young without a tadpole stage -- today the standard for about half of all Modern face a host of threats to their survival, including habitat destruction, human encroachment and climate change. "I think the most exciting thing about our is that we show that are such a strong animal group," said lead author Peng Zhang, a researcher at Sun Yat-sen University in Guangzhou, "They survived from the mass that completely erased and boomed back quickly.

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First Published: Tue, July 04 2017. 04:22 IST