Rising temperatures pose a complex threat to lizards populations


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Scientists surgically implanted temperature sensors on spiny lizards in order to measure the effect of shade on body temperature. (Renee Grayson/flickr)
Jenna Ladd | September 6, 2016

Countless animal species are negatively affected by climate change, but a recent study suggests that lizards have it particularly rough.

Following a major international survey published in the journal Science, it was predicted that if current trends continue, 20 percent of all lizard species could go extinct by 2080. An international team of biologists led by Barry Sinervo at the University of California, Santa Cruz researched the effects of rising temperatures on lizard populations around the world. Using their findings, the group developed a predictive model of extinction risk. Sinervo said, “We did a lot of work on the ground to validate the model and show that the extinctions are the result of climate change.” He added, “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.”

Lizards are especially sensitive to warming climates because they regulate their body temperature using the environment around them. Michael Sears, a biologist at Clemson University, said that previous extinction models made the assumption that lizards are able to find shade immediately in their respective environments, which could mean models are inaccurate. Sears and his colleagues researched how the availability of shade affects lizards’ ability to achieve an optimal body temperature.

The researchers implanted small temperature sensors into dozens of spiny lizards and tested how the animals reacted to constructed areas of shade within New Mexico desert enclosures. They found that the lizards fared better in environments when several small areas of shade were available, in comparison with enclosures that had just a few large areas of shade. Sears explained, “It’s sort of like, if you were out jogging, and there was only one tree and it was a long way to the next one, and it was a hot day — that’s a bad environment. But if there were a bunch of trees along the way providing little bits of shade, you’d feel a lot better.”

The study concluded that extinction predictions for lizards are not uniform across all populations. In general, lizards that live in cooler environments may actually benefit from climate change, while those that live in hotter areas are likely to suffer. As for all those in between, Sears said we can’t be sure, “All bets are kind of off now. Because what our study suggests is that how bushes are placed in an environment might really impact the lizards just as much as the temperature itself.”

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