Global climate change is driving lizards to extinction, imperiling the ecological web of life that depends on these ancient creatures, according to an international research effort led by UC Santa Cruz ecologist Barry Sinervo.

Lizards' lives are closely tied to temperature — if it gets too hot, they seek refuge in burrows where there's no food. If it stays hot too long, the creatures will eventually starve, said Sinervo, who has studied lizards in the wild for 26 years and keeps 200 of them for closer study in a campus greenhouse.
The findings, published in the journal Science, are “devastating and heart-wrenching,” said Sinervo. “I don't want to tell my child that we once had a chance to save these lizards, but we didn't.”
The disappearance of lizard populations is likely to have repercussions up and down the food chain because lizards are important prey for many birds, snakes and other animals, and they are important predators of insects.
Sinervo's research team found that rising temperatures have driven to extinction 12 percent of Mexico's populations of the lizard Sceloporus, or mesquite lizard, which lives among cactus and chaparral.
Then, they compared their Mexican field studies with extensive data about 1,216 lizard populations on four continents, contributed by colleagues in Spain, Argentina, Australia, Madagascar and elsewhere. They estimated that 4 percent of all lizard populations have gone extinct worldwide since 1975 — and in some places, such as Madagascar, 21 percent of species have been lost.
They studied the effects of rising temperatures on lizards' bodies and, in their Santa Cruz lab, used climate data to create a mathematical model of extinction risks for lizard species around the world.
It forecasts a grim future: Six percent of lizard species will be extinct by 2050. By 2080, if nothing is done to slow climate change, the number will rise to 20 percent, according to the model.
In a critique of the study, Science editor Andrew Sugden said, “This work is a fine example of interdisciplinary science and international collaboration.”
At greatest risk are lizards at low elevations and low latitudes, where it is warmer, according to the team. In the United States, lizards in Texas and Southern California are most vulnerable. No Northern California lizards are thought to be at risk because it is cooler here.
Many scientists have presumed that animals would simply move to cooler climes, or evolve to cope with rising temperatures.
But lizards can't escape “this toaster oven,” University of Washington's Raymond Huey and colleagues write in an analysis accompanying the study. Lizards are more susceptible to climate-warming extinction than thought, because many species are already living right at the edge of their thermal limits, especially in warmer climates. “Lizards don't go that far. They don't disperse,” said UC Santa Cruz graduate student Elizabeth Bastiaans, who samples lizard populations in the vast deserts of Texas and Mexico.
What Jane Goodall was to chimps, biologist Sinervo is to lizards. He grew up in Canada, “where I used to catch frogs and salamanders. I dreamed of catching lizards, but there were not a lot there,” he joked. He came to California because of the state's reptile diversity.
(Source: San Jose Mercury News)