Frogs are among some of the most diverse vertebrates on the planet, but their origins have long been cloudy. On the other hand, researchers may have just stumbled upon an important discovery that illustrates how a plethora of frog species came to be.
Image Credit: Saguari/Pixabay
In the journal Proceedings of the National Academy of Sciences (PNAS), biologists hailing from both the University of California, Berkley and Sun Yat-Sen University in China detail how the asteroid strike that wiped out the dinosaurs may have laid out a red carpet for many of today’s diverse frog species.
It’s quite the polarizing find, especially since many researchers believe that today’s frog species came into existence several million years before this asteroid ever slammed into Earth. Nevertheless, study co-author and herpetologist David Wake is convinced that the new findings are the most accurate to date.
"We think the world was quite impoverished as a result of the KT event, and when the vegetation came back, angiosperms dominated. That's when trees evolved to their full flowering," Wake explained in a statement.
"Frogs started becoming arboreal. It was the arboreality that led to the great radiation in South America in particular."
Worthy of note, tree frogs became much more diverse after the asteroid strike, and they survived well because the tree’s branches and leaves helped shield the critters from predators, which made tree frogs much more adept at surviving.
But it wasn’t just the adaptation of tree-living that resulted from the event; the researchers also say that it led to more frog species being born directly from eggs, skipping the tadpole stages seen in several frog species.
"The majority of the frogs that thrive now are thriving because of direct development of eggs in terrestrial situations," Wake continued. "It is a combination of direct development and use of arboreal habitat that accounts for a great deal of the radiation."
Because genetic information on frogs is so limited, the researchers sampled up to 95 genes from the DNA of more than 150 frog species. They used their newly-collected samples together with ones previously collected from another 140 frog species, which helped them compile a family tree for the study.
Although the findings of the study contradict previous beliefs, the data reminds us about the mechanisms of evolution. Organisms are more likely to evolve for survival when the environment is dynamically changing around them, and an asteroid strike would have imposed significant changes to the frogs’ natural environment.
Scientists think that the Earth was a calm and peaceful place before the asteroid strike, so there weren't many catalysts for the evolution before the asteroid hit.
"These frogs made it through on luck, perhaps because they were either underground or could stay underground for long periods of time," Wake said.
"This certainly draws renewed attention to the positive aspects of mass extinctions: They provide ecological opportunity for new things. Just wait for the next grand extinction and life will take off again. In which direction it will take off, you don't know."
Since the study only considered approximately 300 of today’s 6,700 known frog species, additional research into a greater diversity of frog species could help validate the new findings and advance our knowledge of frogs.