These lizards have a hot trick to escape hungry snakes

Mr. Yuan ventured to the Izu Islands with a tripod and a makeshift running track strapped to his back. After catching lizards on Kozu, an island with snakes, as well as the Hachijo-Kojima without snakes and weasels, Mr. Yuan recorded the lizards running along the track with a camera to calculate their running speed at different temperatures. bodily.

Lizards and snakes are both ectotherms, which means their body temperature is dependent on their surrounding thermal environment. Body temperature, in turn, affects their ability to move; motionless in cold weather, their movement speed increases as they warm up, before reaching a plateau and decreasing rapidly when it is too hot.

The researchers found that island lizards with snakes run faster at higher temperatures, suggesting they were more suited to warmer body temperatures, Yuan said. At these higher body temperatures, lizards sprinted faster than snakes could crawl.

The presence of predators also had evolutionary effects on the bodies of lizards; lizards on islands with snakes had longer hind legs.

“We basically link the presence of snakes to faster-running lizards, those lizards having longer legs and those lizards foraging at warmer body temperatures,” said Mr. Yuan, the study’s lead author.

Data collected for the study also highlighted another fortuitous, albeit worrying, finding. The Izu Islands have only warmed since Dr Hasegawa first set foot there, as have the lizards. From 1981 to 2019, the average body temperature of lizards increased by 2.3 degrees Fahrenheit across all of the islands, correlating with global warming.

Rising temperatures can threaten ectotherms, which include the majority of animal species, and alter the dynamics of prey-predator relationships, said Shane Campbell-Staton, an evolutionary biologist at the University of California at Los Angeles, who did not participated in the study.