When Elizabeth Bastians of UCSC went to Mexico this year, she expected to find hordes of lizards there. There weren’t, and Bastians claims that this is an indication of things to come. In a paper released yesterday, she and her coathours argue that some 20 percent of the world’s 5,000 lizard species could go extinct by 2080 as a result of global warming. “The sites where there had been the greatest change in temperature were the ones where the lizard had gone extinct,” she says.
UCSC ecology and evolutionary biology professor Barry Sinervo, the lead author of the article, explains that when the temperature heats up, lizards, which are cold-blooded animals who cannot regulate their body temperatures, are forced to seek shelter in the shade, limiting the time they have to hunt for food. Another coauthor, Jack Sites of Brigham Young University, adds that higher temperatures drain the lizards’ energy, especially during reproductive cycles, so that they don’t have the strength to support their eggs or embryos. “They simply don’t reproduce,” he says.
The study, which involves 26 researchers from 12 countries, points out that some 4 percent of lizard species have gone extinct since 1975. The implications of this are explained by Aaron Bauer of Villanova University. He explains that since lizards are an integral part of the food chain, their disappearance will affect animals both above and below them. For example, lizards are important predators of insects, so that if they disappear, insect populations, now kept in check, could rise. On the other hand, lizards are eaten by snakes and birds. A population decline among lizards could impact the snake and bird population too.
Sinervo is convinced that the declining populations result from climate change, rather than loss of habitat. He adds that even if measures are taken to check greenhouse gas emissions, many species may have reaches a tipping point, and can no longer be brought back from the brink of extinct. At least 6 percent of existing lizard species could be gone in just 40 years. Read more at ABC and USA Today.
