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Dinosaurs’ loss was frogs’ gain: The upside of a mass extinction

New and more complete genetic data pinpoints this radiation much earlier: 66 million years ago at the Cretaceous-Paleogene boundary, precisely when much of life on Earth was wiped out by a comet or asteroid.The research team combined the found genetic information from frogs with additional 145 species to try and produce a sort of a family tree which is based on the various genetic relationships. This new study shows that modern frogs have three lineages and, according to the newest evidence, all three appeared nearly simultaneously at the origin point. “This finding was totally unexpected”.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.The researchers then used fossil records to translate genetic differences between frog lineages into dates at which they likely diverged from one another. The third, Hyloidea, spread throughout what became South America. “That’s when trees evolved to their full flowering”, says co-author David Wake, of the Museum of Vertebrate Zoology at the University of California, Berkeley.Similar evolutionary events happened with birds, said co-author David Hillis, professor of integrative biology at University of Texas, Austin.The sudden surge in diversification, Blackburn suggested, was down to the frog stepping up to fill in a few niches left by other creatures, many of whom had died off after the impact. Though this is but a fraction of the 6,775 frog species so far identified, it covered all 55 frog families and importantly included a greatly expanded sequencing of 156 frog species from 44 of those families.”We think there were massive alterations of ecosystems at that time, including widespread destruction of forests”, said Blackburn.”But frogs are pretty good at eking out a living in microhabitats, and as forests and tropical ecosystems rebounded, they quickly took advantage of those new ecological opportunities”.Are humans a greater threat than an asteroid?It seems that the enormous diversity of frogs on our planet is a direct effect of the asteroid strike that was responsible for the dinosaur extinction.