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Large toe pads give some lizards a leg up during a hurricane

After 2017’s devastating hurricane season, the cities, islands, and coastal communities hit hardest were left to pick up the pieces and forge a long road to recovering basic essential services like providing clean water, clearing roadways to hospitals, evacuating trapped residents, and restoring power.  

It’s estimated that damage from the 2017 hurricane season cost around $282 billion, one of the costliest seasons on records

For biologists at Washington University in St. Louis and Harvard, though, hurricane Irma afforded a fortuitous research opportunity into natural selection events and how lizards in the remote cays of Turks and Caicos weathered the storm.

The one of a kind study on the physical characteristics that can make the difference between life and death in the middle of a hurricane was published in the journal Nature.

“Hurricanes are in the news, and it seems that they’re becoming more destructive,” said Jonathan Losos, a member of the research team. “Something like this has never been documented before because it’s so difficult. The timing had to be just right.”

The study did not start out as an examination of natural selection events but that’s what it morphed into after it became apparent that data collected on lizard populations for an invasive species eradication project could be used for before and after Irma comparisons on lizard species.

The researchers were granted rare access to their original research areas on remote islands in Turks and Caicos after hurricane Irma.

“Heading back to Pine Cay, we weren’t sure what we’d find, but when we got to the field and saw a few lizards running around, we were eager to get catching and start measuring,” said Colin Donihue, the lead author of the study. “We walked exactly the same transects we had the last time. There were definitely fewer lizards. We had to work harder to catch our sample size.”

For two days, Donihue and Losos and their team collected 100 lizards on two separate islands, recording data on forelimb, hindlimb, and core body strength measurements.

The researchers also took pictures of the lizards’ toe pads in hopes that it would show why some lizards survived over others. The new data was compared to the data collected before the hurricane had hit.

“The prediction was that if we saw any changes, they would be changes in the features that help lizards hold on — they would be related to clinging ability,” said Donihue. “For example, the sticky toe pads on their fingers and toes, maybe they would be larger.”

It was the lizards that had larger toe pads on both forelimbs and hindlimbs with shorter bones between their hips and knees that survived. Surviving lizards also had smaller bodies.

The researchers were then curious if these traits gave the lizards an advantage during the hurricane and the results seem to indicate that this is the case.

“With regard to evolution, the question is whether hurricanes cause selective mortality: do individuals with certain traits survive better than individuals with different traits?” Losos asked. “The alternative possibility — that devastation is so massive that mortality is indiscriminate, not favoring some individuals over others — is certainly possible. Still, hurricane-induced natural selection seems like the best explanation for these findings.”

There are still missing pieces to the study and further research is needed to understand how lizards behave during a hurricane and the self-preservation methods they employ.

Lizards are built to cling, but not all lizards are built equally as the study show, and some lizards with larger toe pads may be better suited to weather hurricane force winds compared to their long-legged, long-bodied counterparts.

The study also calls attention to the importance of better understanding how hurricanes affect entire ecosystems and species populations.

“We know that hurricanes are getting more frequent, and we know that they’re getting more strong,” said Donihue. “So, setting up a network of sites that are actually set up to investigate the question of how hurricanes are changing the evolutionary trajectory of species I think could be really useful.”

By Kay Vandette, Staff Writer

Image Credit: Colin Donihue

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