Washington: Geologists have found clues to origin of the Himalayas and the Tibetan plateau - by analysing evolution of a group of muscled frogs.
Scientists from Kunming, China, and the University of California, Berkeley, found that 24 species of spiny frogs from the tribe Paini evolved along with the mountains.
They were uplifted, developed hard, nubby spines and Popeye-like arms to hold onto their mates in the swift-running streams roaring down from the highest mountains in the world.
Frogs that live in fast-flowing streams, have muscular forearms combined with sandpaper-like spines to prevent the slimy female from slipping.
This evolutionary sequence, in turn, tells geologists the sequence in which mountain ranges and river systems arose and isolated as a result of the Indian tectonic plate pushing northward into Asia.
"We use these frogs as a surrogate for a time machine," said David Wake, a herpetologist and evolutionary biologist.
According to the researchers, the tribe Paini arose in what is now Indochina and spread into Western China about 27 million years ago.
It diverged into two groups: Nanorana, now consisting primarily of high-elevation species up to 4,700 meters, in Western China; and Quasipaa, consisting of mostly low-elevation species in Indochina and South China.
As the Tibetan plateau was pushed higher, it became separated from the Himalayas - populations restricted to the Himalayas are now considered the Paa subgenus.
The Nanorana subgenus isolated in Tibet began to diversify again about 9 million years ago, consistent with the period during which the Tibetan plateau rose above 3,000 meters.
"Basically, the frogs were rafting on top of the continents," An Yin said.
"The tectonics control morphological evolution by transporting originally very closely related frogs so far apart they all diverge and develop very differently," Yin added.
The study is published in the journal Proceedings of the National Academy of Sciences.