Wednesday, May 19, 2010

warming extinguishing lizards

The Scientist | The worst-case scenario of the consequences of global warming - mass extinctions - appears to be a reality for lizards, according to a new report in Science.

The authors found that 12 percent of local populations of lizards have already disappeared from hundreds of sites in Mexico. Furthermore, within the next 70 years, the authors predict that 1 in 5 lizard species will no longer exist anywhere on the planet, all the result of rising global temperatures.

Although a growing amount of data is showing the impact of climate change on species, these lizard extinctions were somewhat surprising, said Jack Sites, an evolutionary geneticist from Brigham Young University, and last author on the paper. "I had always presumed that lizards would be able to adapt to climate change by simply altering their behavior," he said. "However, this is not the case."

Rather, the changes in local temperatures are occurring too quickly for evolution to keep pace, he said. "So we have extinctions instead."

The study began when the authors returned to 200 sites in Mexico that were home to 48 species of Sceloporus lizards, which had already been sampled in 1975 and 1999. They saw that 12 percent of lizards in the Mexican study area were already locally extinct -- meaning, environmental stressors had eliminated the populations in these particular areas.

This alarming rate of extinction prompted first author Barry Sinervo, a herptologist at the University of California, Santa Cruz, and his colleagues, to dig more deeply into the impacts of climate change on lizards.

Lizards regulate their body heat by basking in the sun; too hot, and they retreat to shade. Too much time in the shade, however, and they become unable to gather enough food to grow and survive.