From a press release from Villanova University, more worry. I don’t know about the researchers experiences, but my property is overrun with the Western Fence Lizard. I can hardly avoid stepping on them there are so many around the house. Personally, I don’t understand the linkage between warmer temperatures and lizard extinction as I’ve yet to see a lizard who didn’t want to warm itself up in direct sunshine or on heat radiating rocks/concrete/asphalt.
Maybe the researchers never saw the story about Iguanas dying and falling out of trees due to cold this past winter. Anyway, I’ll sure miss Godzilla.
International team of biologists, including Villanova University’s Dr. Aaron Bauer, find alarming pattern of population extinctions attributable to rising temperatures.
An international team of biologists has found an alarming pattern of population extinctions attributable to rising temperatures. If current trends continue, up to 20 percent of all lizard species are predicted to go extinct by 2080. The study was published in the May 14th issue of Science.
The researchers, led by Barry Sinervo, professor of ecology and evolutionary biology at the University of California, Santa Cruz, conducted a major survey of lizard populations worldwide, studied the effects of rising temperatures on lizards, and used their findings to develop a predictive model of extinction risk. Their model accurately predicted specific locations on five continents (North and South America, Europe, Africa, and Australia) where previously studied lizard populations have already gone locally extinct. Based on the predicted probabilities of local extinction, the probability of species extinction was estimated to be 6 percent by 2050 and 20 percent by 2080. As the ongoing extinction of populations is directly related to climate change, limiting the carbon dioxide production that is driving global warming is crucial for avoiding the wave of lizard extinction in future.
“We did a lot of work on the ground to validate the model and show that the extinctions are the result of climate change,” Sinervo said. “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.” While recent global extinctions of amphibians are not directly related to climate change, but largely due to the spread of disease, the ongoing extinctions of lizards are due to climate warming from 1975 to the present.
The disappearance of lizard populations was first recognized in France and then in Mexico, where 12 percent of the local populations had gone extinct since the lizards had previously been studied. Although the lizards normally bask in the sun to warm up, higher temperatures exceeding their physiological limits keep them in the shade, restricting their activity and preventing them from foraging for food. The researchers used these findings to develop a model of extinction risk based on maximum air temperatures, the physiologically active body temperature of each species, and the hours in which its activity would be restricted by temperature. The model accurately predicted the disappearance of Mexican lizards and was then extended globally to lizards in 34 different families on five continents and validated by comparing the predicted results with actual local extinctions.
Data for African lizards was provided by Villanova University professor Aaron Bauer, whose research focuses on the evolution of geckos and other reptiles in the Southern Hemisphere. Bauer, who is the Gerald M. Lemole M.D. Endowed Chair of Integrative Biology, has worked in southern Africa for more than 20 years and has described more than 100 new species of lizards from around the world. Although the predicted extinction risk for the African lizards studied was low, neighboring Madagascar can expect to lose many species and extensive local extinctions have already been documented. “In many parts of the world, lizards are almost certainly going extinct due to climate change before their very existence is known to biologists” said Bauer, whose research is funded by the National Science Foundation.
Bauer believes that most Americans, particularly those in the northeast, where there are few – often inconspicuous – lizard species, are unaware of their ecological importance. However, the disappearance of lizard populations is likely to have repercussions up and down the food chain. Lizards are important prey for many birds, snakes, and other animals, and they are important predators of insects.
The climate projections used to model extinction risks assume a continuation of current trends in carbon dioxide emissions from human activities. Many of the extinctions projected for 2080 could be avoided if global efforts to reduce emissions are successful, but it may be too late to avoid the losses predicted for 2050.
Funding for this study came from grants from the National Geographic Society, National Science Foundation, and a diversity of international funding bodies.
In fairness, a second press release, from AAAS about the same subject issued minutes after the Villanova release at least has some supporting data imagery. See below.
In fact, there was a group of rapid fire press releases withing minutes that hit Eurekalert:
20 percent of all lizard species could be extinct by 2080, researchers say
This press release is available in Chinese, Japanese, Spanish, French, Portuguese and Finnish. Surveying Sceloporus lizard populations in Mexico, an international research team has found that rising temperatures have driven 12 percent of the country’s lizard populations to extinction. An extinction model based on this discovery also forecasts a grim future for these ecologically important critters, predicting that a full 20 percent of all lizard species could be extinct by the year 2080.
The detailed surveys of lizard populations in Mexico, collected from 200 different sites, indicate that the temperatures in those regions have changed too rapidly for the lizards to keep pace. It seems that all types of lizards are far more susceptible to climate-warming extinction than previously thought because many species are already living right at the edge of their thermal limits, especially at low elevation and low latitude range limits.
Caption: Global maps of observed local extinctions in 2009, and projections for 2050 and 2080 based on geographic distributions of lizard families of the world.
Although the researchers’ prediction for 2080 could change if humans are able to slow global climate warming, it does appear that lizards have crossed a threshold for extinctions—and that their sharp decline will continue for decades at least.of California in Santa Cruz, along with colleagues from across the globe, reached these conclusions after comparing their field studies of the lizards in Mexico with extensive data from around the world. Their research will be published in the May 14 issue of Science, the peer-reviewed journal published by AAAS, the nonprofit science society.
After compiling the global field data, Sinervo and his colleagues studied the effects of rising temperatures on lizards’ bodies, and created a model of extinction risks for various lizard species around the world. Their model accurately predicted specific locations on five continents where populations of lizards have recently gone extinct, and it might inform researchers on how these patterns of extinction will continue in the future.
“How quickly can Earth’s lizards adapt to the rising global temperatures? That’s the important question,” Sinervo said. “We are actually seeing lowland species moving upward in elevation, slowly driving upland species extinct, and if the upland species can’t evolve fast enough then they’re going to continue to go extinct.”
According to the researchers’ global model, which is derived from today’s trends of carbon dioxide emissions from human activities, about six percent of lizard species are due for extinction by the year 2050. Since carbon dioxide hangs around in the atmosphere for decades, the researchers say that this statistic can no longer be avoided. However, they do say that concentrated global efforts to reduce carbon dioxide in the atmosphere could possibly avert the 2080 scenarios, in which 20 percent of lizard species are expected to disappear from the planet.
The detailed study notes specifically that lizards that bear live young are particularly at risk of extinction, compared to those that lay eggs. “Live-bearers experience almost twice the risk of egg-layers largely because live-bearers have evolved lower body temperatures that heighten extinction risk,” Sinervo said. “We are literally watching these species disappear before our eyes.”
Sinervo began focusing his attention on lizard extinctions after he noticed an obvious trend during his field work in France. He identified an unsettling pattern of lizard extinctions with French researchers, Jean Clobert and Benoit Heulin, while they were surveying some of their well-documented populations. Disturbed by their findings, they contacted colleagues around the world—Jack Sites and Donald Miles in the United States, Fausto Méndez-de-la-Cruz in Mexico, and Carlos Frederico Duarte Rocha in Brazil—and a global collaboration ensued.
“This work is a fine example of interdisciplinary science and international collaboration, using methods and data from a range of scientific disciplines to improve confidence in the prediction of the biological effects of contemporary climate change, and in particular showing how long-term records and research are so crucial to the understanding of ecological change,” said Andrew Sugden, the International Managing Editor of Science.
“We would never have been able to do this without certain free, online tools like Google Scholar and Google Earth,” Sinervo said. “It took us awhile to pinpoint the appropriate search terms. But once we did, we locked onto key published studies. I was surprised at how fast researchers began sending us data… That’s what happens though: When scientists see a problem, with global evidence backing it, they come together.”
In order to fine-tune their model with this surprising global outpouring of data, Sinervo and his colleagues used a small electronic device that mimics the body temperature of a lizard basking in the sun. They placed these thermal models in sun-drenched areas for four months at sites in Mexico where lizard populations were still thriving—and at sites where they have already gone extinct.
“There are periods of the day when lizards can’t be out, and essentially have to retreat to cooler places,” Sinervo said. “When they’re not out and about, lizards aren’t foraging for food. So we assessed how many hours of the day lizards would have been driven out of the sun at these different locations. Then, we were able to parameterize our global model.”
For the authors, who claim a deep appreciation for these lizards and the important role the reptiles play in the global food chain, these findings are both “devastating and heart-wrenching.” But, they say, hope does remain for the world’s lizards.
“If the governments of the world can implement a concerted change to limit our carbon dioxide emissions, then we could bend the curve and hold levels of extinction to the 2050 scenarios,” Sinervo concluded. “But it has to be a global push… I don’t want to tell my child that we once had a chance to save these lizards, but we didn’t. I want to do my best to save them while I can.”