Tuesday, January 09, 2007

Amphibians: don't cry for me, Al Gore

Amphibians are valued for their seeming susceptibility to global warming. Many climate scientists point to their fragility and see them as the canary in the coal mine of global warming.

While this may be true of individual species, amphibians as a group do rather well over time. Their ability to bounce back from previous climate *disasters* is better understood thanks to a recent study in the journal Proceedings of the National Academy of Sciences summarized by New Scientist:
Amphibians bounced back spectacularly from a series of mass extinctions during their evolution, according to a new genetic analysis.

In the present day, biologists see amphibians as sentinels of environmental change. The extreme sensitivity of their skin makes them more prone than other organisms to soaking up toxins and suffering from fungal infection, and provides little protection from ultraviolet radiation, which causes genetic mutation. [...]

That said, a look at their latest evolutionary tree reveals that amphibians have a remarkable capacity to bounce back from environmental changes, says Kim Roelants of Vrije University in Brussels, and colleagues.

Their new research suggests that the amphibian class as a whole has recovered spectacularly from a series of mass extinction events that affected all life on earth, with explosive booms of speciation. "For instance, right after dinosaurs went extinct 65 million years ago, at the Cretaceous-Tertiary border, there was a huge explosion of frog species," he says. [....]