Global warming leading to lizard extinction, BYU professor says

Published: Friday, May 14 2010 1:14 a.m. MDT

An Australian bearded lizard perches on the shoulder of Dr. Jack Sites, herpetologist and geneticist at BYU.

Jaren Wilkey, BYU

Enlarge photo»

PROVO — For the first time in his academic career, BYU professor Jack Sites hopes his research will be proved wrong. For a herpetologist and evolutionary geneticist, it's depressing to be involved in a study that predicts 20 percent of lizard species will be extinct by 2080 due to global warming.

"This is quite stunning," said lead author Barry Sinervo, a professor of ecology and evolutionary biology at the University of California Santa Cruz. "You think of lizards as desert adapted and capable of taking high temperatures."

But their study, being published this week in Science, points out that warmer temperatures are stopping lizards from foraging as much as they used to, which means they don't have enough energy to reproduce.

"They miss the reproduction and it doesn't take but a couple of generations and then the population crashes," said Sites, whose research beginning in 1977 sparked the study.

As a graduate student in Texas, Sites designed a dissertation project around spiny lizards in Mexico and studied them every summer until the early '90s.

But later, when ecologists asking different research questions went to the same locations, they couldn't find any lizards, or if they did, they were very, very rare, Sites said.

"If anybody's been out in the desert on a spring day, if you're halfway paying attention, lizards are easy to find," Sites said.

So, Sinervo and other curious colleagues began gathering data from weather stations in the area and discovered that the only change in the lizards' habitat was a temperature increase.

"Barry thinks big," Sites said. "He's a major synthesizer. (He asked) 'Is it only this group or is it more widespread?' "

From there, Sinervo contacted colleagues in Europe and Sites worked his network in Patagonia to cull all available lizard information. Twenty-four other authors collaborated on the paper.

With data from unrelated groups of lizards across five continents, including some recently extinct species, Sinervo created a statistical model that accurately reflected past extinctions and predicted future losses.

"It hit us all like a punch in the gut," Sites said. "I'm not an ecologist, but I just didn't anticipate anything like this."

The temperature increase is happening faster than the lizards can adapt, which means widespread extinction unless CO2 production is changed and limited, Sinervo said.

The loss of lizards not only diminishes the beauty of nature, it decreases biodiversity and punches a hole in the food chain, Sites said.

Lizards eat the bugs and small invertebrates passed up by bigger animals because of their small caloric rewards, Sites explained. Eliminate lizards and not only will bugs increase, but bigger, lizard-eating animals will suffer.

"This is just the tip of the iceberg," Sinervo said. "Many other systems, for example, agricultural systems, are likely to feel the strains of climate change. We are going to see systems begin to collapse due to climate-warming effects."

e-mail: sisraelsen@desnews.com

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