02 June 2012


Today's weather - sunny
I read an interesting article "Ecosystems that thrive in Amazon's High Places" on page 13 in The New York Times in this morning's TODAY.

Tepuis, which are known as tabletop mountains because of its flat plateau and steep cliff faces, located in the northern Amazon rain forest emerge thousands of meters from lowland forests and support a high biodiversity of flora and fauna such as lizards and frogs. Like mountains in the sky, it is a natural wonder how these are formed in the first place and how the animals get up there.

Unlike the formation of natural mountains such as the Andes which result from the collision of continental plates 25 million years ago, tepuis were hypothesized to form about 70 million years ago as layers of rock with sand at the ocean bottom were raised to become dry terrestrial land and over time, erosion removed the sand and exposed the rock beneath. Interestingly, it was found that the many faunal species living atop the tepuis are not found anywhere else and yet appeared to be closely related to each other, bringing forth the conjecture that they may share a common ancestral lineage.

According to recent research studies on 4 species of tiny tree frogs that live on these tepuis, evolutionary biologists are able to use their DNA molecular clock and compared them to their closest lowland relatives to determine how long ago their common ancestor existed before it accumulated new mutations and diverged into separate species. It was discovered that the common ancestor of these 4 frog species lived about 5.3 million years ago, and not 70 million years ago. This means there is a possibility that the frogs scaled up the colossal cliffs to the tepuis and became separate species only several hundred thousand years ago.

Unfortunately, global warming has driven the mountain-dwelling species to higher altitudes but they can only go as far and as high as the top of the tepuis. I am ending this post with a quote from Ms Patricia Salerno, the lead evolutionary biologist, from the University of Texas, involved in the study:
"The tepui frogs may have been able to scale cliffs that would make mountaineers blanch. But even they can't climb into thin air."