Speaking of “on top of the world”, Carl Zimmer tells the story of a recent discovery about the Amazonian table-top mountains:
Even more intriguing than the tepuis’ long isolation is that many species living atop them are found nowhere else.
To many biologists, the only explanation that made sense was that the ancestors of those unique animals and plant species have lived on the tepuis for more than 70 million years. In honor of Conan Doyle, they called this notion the “lost world hypothesis.”
Ms. Salerno realized that genetics offered a straightforward way to test this hypothesis. Over time, species accumulate new mutations in their DNA at a roughly regular rate. When two species diverge from a common ancestor, their DNA becomes steadily more different. Biologists can use this so-called molecular clock to estimate how long ago their common ancestor lived.
Another reminder of how determined evolution (and frogs) can be! —Uncle Eb/John