Asteroid Extinction Event That Wiped Out Dinosaurs Cleared Way For Diversification Of Frogs
The asteroid that struck Earth about 66 million years ago doomed the dinosaurs, but scientists have found evidence suggesting that frogs benefited from the event.
Frogs Diversified After Asteroid Struck Earth 66 Million Years Ago
Findings of a new analysis, which was published in the journal PNAS, revealed that the population of frogs exploded after the mass extinction.
In the new study, researchers conducted an analysis of 95 genes from frogs within 44 of the 55 living families and found that three major lineages of modern frogs surfaced simultaneously and evolved at the end of the Cretaceous and the start of the Paleogene, the so-called K-Pg boundary, or KT boundary, the time when the extinction event believed to have been triggered by a massive extraterrestrial rock took place.
"Our divergence-time analyses show that three species-rich clades (Hyloidea, Microhylidae, and Natatanura), which together comprise ∼88% of extant anuran species, simultaneously underwent rapid diversification at the Cretaceous-Paleogene (K-Pg) boundary (KPB). Moreover, anuran families and subfamilies containing arboreal species originated near or after the KPB," the researchers wrote in their study.
"These results suggest that the K-Pg mass extinction may have triggered explosive radiations of frogs by creating new ecological opportunities."
Ecological Opportunities For The Frogs
It is not certain why these three lineages outperformed the others that were living at the time of the mass extinction event, but scientists think that the three lineages were at the right place and right time.
The primary ancestors of modern frogs likely took advantage of the ecological opportunity after the mass extinction and explosively evolved new species.
Seed-bearing trees and other flowering trees started to dominate the landscape and the three frog lineages contain species that dwelt in trees, which was not previously seen in these amphibians. Researchers think that arboreality, or living on trees, has benefited frogs.
Many new species of frog also began laying their eggs on lands and skipped the tadpole phase to grow directly into a small frog, a trait that characterize about half of the 6,775 currently known frog species.
The researchers said that new species of frog likely radiated rapidly around the world at the time because many environmental niches became available after the animals that used to occupy them have disappeared.
"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," said Study researcher David Wake, a herpetologist from the University of California, Berkeley. "Frogs started becoming arboreal. It was the arboreality that led to the great radiation in South America in particular."