Yahoo News 13 May 10;
WASHINGTON (AFP) – Global warming could kill off as many as a fifth of the world's lizards by 2080, with potentially devastating consequences for ecosystems around the world, a study released Thursday said.
Researchers who conducted a major survey of lizard populations worldwide said in a study published in the May 14th issue of Science that lizards appear to be especially sensitive to the effects of climate change and are dying off at an alarming rate.
The loss of the lizard populations could wreak havoc with ecosystems in which they are a crucial part of the food chain, since they are important prey for many birds, snakes, and voracious predators of insects.
The biologists in the study ruled out factors other than global warming as being responsible for the rapid decrease in the lizard population.
"We did a lot of work on the ground to validate the model and show that the extinctions are the result of climate change," said Barry Sinervo, professor of ecology and evolutionary biology at the University of California at Santa Cruz.
"None of these are due to habitat loss. These sites are not disturbed in any way, and most of them are in national parks or other protected areas," he said.
The scientists worked up models based on predicted probabilities of local extinction showing the likelihood of species extinction was estimated to be six percent by 2050 and 20 percent by 2080.
Earlier models, they said, have accurately predicted the extinctions of lizard population on five continents around the world.
The researchers said they first noted the disappearance of lizard populations in France and later in Mexico, where 12 percent of lizard populations are thought to have died out.
Although generally thought to be sun-loving creatures, higher temperatures have proved to be too much for many lizard species, causing them to restrict their activity, including limiting their efforts to find food.
Villanova University professor Aaron Bauer, who specializes in African lizards, said scientists are engaged in a race against time to find and document research on the endangered amphibians.
"In many parts of the world, lizards are almost certainly going extinct due to climate change before their very existence is known to biologists," he said.
Lizards Face Extinction From Global Warming: Study
Mica Rosenberg, Reuters 14 May 10;
Lizards are in danger of dying out on a large scale as rising global temperatures force them to spend more time staying cool in the shade and less time tending to basic needs like eating and mating.
Scientists warn in a research paper published on Thursday that if the planet continues to heat up at current rates, 20 percent of all lizard species could go extinct by 2080.
"The numbers are actually pretty scary," said lead researcher Barry Sinervo from the University of California Santa Cruz. "We've got to try to limit climate change impacts right now or we are sending a whole bunch of species into oblivion."
A mass extinction of lizards, which eat insects and are eaten by birds, could have devastating effects up and down the food chain, but the extent is difficult to predict.
Sinervo made models of lizards with thermal monitors and left them in the searing sun of southern Mexico to measure how the reptiles would react to temperatures at different altitudes.
Lizards bask in the sun not to relax but for self-preservation. As "ectotherms" they depend on the external environment to control their body temperature.
Unlike mammals, when the reptiles overheat they cannot sweat or pant and they have to retreat to the shade or burrow under a rock to cool down.
This biological quirk has already led to the extinction of 5 percent of lizard populations around the world, Sinervo said, as the creatures spend more time scrambling to find shade and less time doing what they need to do to survive.
"(Temperatures are rising) too fast. Evolution can't keep up," said Jack Sites, a herpetologist at Brigham Young University who collaborated with Sinervo's research.
HIGHER GROUND
Lizards come out during the day to warm up and use the time to find food needed to breed.
"The warming temperatures sort of eclipse that activity period ... It gets too hot to forage and they have to go back," said Sites.
"So they don't die directly but they can't reproduce. It only takes a couple of generations of that and the population is going to spiral downward until it goes extinct."
Elizabeth Bastiaans, a doctoral student in Sinervo's lab, started studying lizards in a wilderness outside Mexico City near the Aztec pyramids of Teotihuacan where tourists huff and puff up hundreds of stairs in the blazing sun.
"I've been out there doing a lot of sampling over the past few years and you see the lizards in the morning and you see them in the evening. But in the hottest part of day, it's just too hot, you don't see them at all," Bastiaans said.
Some of the spiny lizards with blue bellies she studies went extinct at lower, warmer altitudes. Some moved to higher, cooler ground but, as temperatures continue to rise, that habitat is shrinking.
"If the climate continues to warm, they are going to get pushed off the top of the mountains," Bastiaans said. "There is only so much mountain they can climb."
(Editing by Maggie Fox and John O'Callaghan)
Rising global temperatures cooking lots of lizards
Randolph E. Schmid, Associated Press Yahoo News 13 May 10;
WASHINGTON – Sometimes it can be too darn hot even for a lizard.
Cold-blooded creatures that have to soak up the rays to get going might seem like the last animals you would expect to be threatened by global warming.
Well, you would be wrong, researchers say.
It turns out lizards are going extinct in many places, and scientists who have studied them say it's because of rising temperatures. The heats affects reproduction.
"The results were clear. These lizards need to bask in the sun to warm up, but if it gets too hot they have to retreat into the shade, and then they can't hunt for food," said Barry Sinervo of the Department of Ecology and Evolutionary Biology at the University of California, Santa Cruz.
He said he was "stunned and saddened" by the finding, reported in Friday's edition of the journal Science.
"This is an extinction alert for all areas of the globe and for all the various species of lizards," Sinervo said.
Lizards are an important part of the food chain because they are major consumers of insects and in turn are eaten by birds, snakes and other animals.
"This is just the tip of the iceberg," Sinervo said. "It heralds that we have entered a new age, the age of climate-forced extinctions. Extinctions are not in the future. They are happening now."
In Mexico's Yucatan region, scientists found that the time lizards could be out foraging had disappeared. "They would barely have been able to emerge to bask before having to retreat," Sinervo said.
Jack Sites, a biology professor at Brigham Young University, said high temperatures during the reproductive cycle prevent the animals from eating enough to have the energy to support a clutch of eggs or embryos.
"The heat doesn't kill them. They just don't reproduce," he said. "It doesn't take too much of that and the population starts to crash."
According to Sinervo, the extinctions are concentrated in what biologists call hot spots of biodiversity, where there are lots of species.
This includes locations in Mexico, where a large number of species have evolved in the different volcanic mountain ranges. He said there also are massive extinctions occurring in the Amazonian Basin and equatorial Africa, though researchers don't know the magnitude because not all the species have been described from these areas.
In Madagascar, the Indian Ocean island off the southeastern coast of Africa, the estimate is that one-fifth of all the local lizard populations are now extinct, Sinervo said. "This will surely have driven some endemic species to the brink of extinction, if not over the precipice," he said in an interview via e-mail.
Sinervo was doing field work in France when he noticed a decline among lizards. While resurveying areas that had been studied in the 1990s, it became clear that lizards were gone from some spots — levels of 30 percent extinction across southern Europe, for example.
He and French researchers contacted colleagues around the world and found similar trends in the United States, Mexico and elsewhere.
"I was surprised at how fast researchers began sending us data," he said. "That's what happens though. When scientists see a problem, with global evidence backing it, they come together."
Funders of the research included the National Geographic Society, University of California Institute for Mexico and the United States; University of California, Santa Cruz; U.S. National Science Foundation; University of Paris; University of Toulouse; National Council on Science and Technology of Mexico; National Scientific and Technical Research Council of Argentina; Academy of Finland; National Autonomous University of Mexico; American Museum of Natural History; Australian Research Council; and Brigham Young University.
