Hold on Tight: Researchers Say Caribbean Lizards Grow Bigger Toes to Survive Hurricanes

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A report by Jan Wesner Childs for Weather.com.

Lizards in the Caribbean have evolved to hold on for dear life — with their toes — in order to survive hurricanes, according to new research.

A study from Washington University in St. Louis published Monday in the Proceedings of the National Academy of Science showed that lizard groups on Caribbean islands that experience more frequent hurricanes develop larger toepads than lizards that experience fewer tropical cyclones.

That trait is a survival mechanism that helps lizards grip vegetation during high winds, and thus avoid being blown away and killed, the researchers said.

“Correcting for things like differences in body size, we found that island populations that had been hit by hurricanes more [frequently] had larger toepads,” Colin Donihue, a postdoctoral fellow in biology at Washington University and lead author of the study, said in a news release.

“Hurricanes seem to be having some sort of additive effect on the evolution of these lizards — that the more hurricanes you have, the larger toepads you have, on average.”

Anolis lizards have specialized toepads that enable them to cling to smooth surfaces. Researchers found that the toepads of surviving lizards after hurricanes were significantly larger than those from before. Photo by Colin Donihue
Anolis lizards have specialized toepads that enable them to cling to smooth surfaces. Researchers found that the toepads of surviving lizards after hurricanes are significantly larger than others.

Donihue and his colleagues looked at populations of Anolis sagrei lizards on 12 islands, as well as 188 Anolis species with ranges from Florida to Brazil. They culled through 70 years of NOAA hurricane data as well as hundreds of measurements of lizard toepads.

The idea that lizards might be growing larger toepads first came to Donihue in 2017, when he finished a previous survey of Anolis lizards in Turks & Caicos just before hurricanes Irma and Maria hit the islands two weeks apart. Donihue did a comparison immediately after the storms that showed the lizards who survived had different physical traits than the general lizard population before the hurricanes.

Donihue and his fellow researchers returned to Turks & Caicos a year later to take new measurements for the most recent study. They discovered that a new generation of lizards had also adapted the larger toepads.

The scientists say similar evolutionary responses are likely happening in other animals.

“My best guess is that this isn’t just a lizard thing,” Donihue said. “For any other species affected by hurricanes where survival is non-random, you would predict this same kind of pattern occurring.”

Such adaptations could help species defend themselves against climate change.

“Our best idea right now is that tropical cyclones will become less frequent globally. However, a higher percentage of them will become intense hurricanes,” said Alex Kowaleski, a study co-author who specializes in meteorology and atmospheric science at Penn State University. “Increases in sea-surface temperatures will cause a higher percentage of tropical cyclones that do form to become Category 4 or 5 hurricanes.”

Donihue added that there are likely other evolutionary factors at play in lizard survival besides big, strong toes.

“Most of the selective pressure is to just be good at being a lizard: to go catch food, find a mate and avoid predators,” Donihue said. “These hurricane events are very infrequent and unpredictable, so we expect that there are other selective pressures that are acting on toepads. In other words, over time, these toepads are not going to turn into big snowshoes, or something like that. There’s a balance.”

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