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In Asia, the spiny frog's evolution is shedding light on tectonic events that took place millions of years ago. Photo courtesy Yu Zeng/UC Berkeley.
Spiny frogs of the tribe Paini (a grouping within the family Dicroglossidae) have been used to determine the timing of geological tectonic events that resulted from the Indo-Asian collision millions of years ago, according to a study published in Proceedings of the National Academy of Sciences.
Scientists from Kunming, China, and the University of California, Berkeley, analyzed genes from several species of spiny frog in Asia and found that Paini is made up of two distinct groups, Nanorana and Quasipaa, and five distinct lineages.
The study shows how species from the tribe Paini evolved with the rise of the Himalayas and the Tibetan Plateau. These geological events are believed to have occurred when the land masses of India and Asia collided millions of years ago. About 19 million years ago, the Tibetan Plateau became separated from the Himalayas, isolating spiny frog populations in these regions and leading to diversification.
Further diversification took place about 9 million years ago, resulting in new Nanorana species on the Tibetan Plateau. This diversification is consistent with the period in which the Tibetan Plateau rose to an altitude of about 10,000 feet. The three species of Paini in this region adapted well to their cold, arid surroundings, and some of their organs degenerated in response to the extreme environment of the high-elevation plateau.
Study authors also researched the dispersal pattern of Quasipaa in Indochina and south China. According to the authors, their research supports the hypothesis that in the Himalaya-Tibetan plateau region, an uplift (crustal thickening) and strike-slip extrusion occured simultaneously about 23 to 24 million years ago in reaction to the Indo-Asian collision. The importance of uplift versus extrusion and the timeline in which these tectonic events took place has been debated by geologists.