How can lizards survive hurricanes?

Julia Ravey sits down with biologist & author Thor Hanson, to find the answers behind how animals have adapted to survive extreme weather conditions...

Julia - We are all trying to make adaptations in our own lives to climate change, and while we think about the threat to species, we often don't think about how animal populations are being altered by these extremes. Thor, in the face of extreme weathers, like hurricanes, how have certain animals adapted?

Thor - That is a marvellous question, and there's a really cool answer to it. This story comes to us from the Turks and Caicos islands in the Caribbean, and from an herpetologist named Colin Donahue, who was down there a few years ago studying these little anole lizards. An anole is a small lizard that's a distant cousin to an iguana. The idea behind this study was to go out and measure all of these lizards, and then they were going to remove non-native rats from the island and see how the lizard population responded. So, he had been out there with his team and they had caught a bunch of lizards and done all of these measurements, and then they went back to their respective universities. Two weeks later, two massive hurricanes swept across the Turks Caicos islands back to back. Category four, category five storms; winds reaching 175 miles per hour. Huge storms that flattened the vegetation and uprooted trees. The damage was so severe that the rat project was put on an indefinite hold, but Colin realised that he was in a rare position to study something else. He could go back and study the effects of the hurricanes: had any lizards survived and, if they had, was the post hurricane population different from the population that he had just measured a few weeks before. So, he cobbled together some funding and they all went back down there and found themselves in a scientific deja vu - repeating the exact same experiment they had just done six weeks earlier. They learnt that the population was measurably different. The survivors of the storm were the lizards that had larger toe pads and strong front legs, which made a certain amount of sense intuitively. If you are stuck in this windstorm, trying to hold on, big sticky toe pads and strong legs would make sense. But, they also had measurably shorter back legs, and that was a total mystery to Colin. Luckily, he had planned ahead for mysteries and had travelled down there with a leaf blower in his luggage. He told me he had quite a conversation with the customs officer trying to explain why he was travelling with landscaping equipment for a scientific project, but he needed the leaf blower because he wanted to see how lizards behaved in hurricane force winds, and you can't be standing out there in a hurricane taking notes. So, instead, he recreated a hurricane using a leaf blower on the porch of his hotel room and videotaped these lizards and their behavior. He learned that, in fact, they do hold on with those big toe pads and those strong front legs, but as the wind speed increases, their back legs begin to slip off until finally their entire body is flapping like a flag in the wind. Those short back legs give the lizards an advantage because they reduce the amount of drag on their bodies and they allow them to cling to the sticks just a little bit bit longer. That can be the difference in that severe weather event between life and death or between perishing and survival of the fittest. He realised that what he had measured in that short span of time was not just some behavioral change or some plasticity giving the lizards the chance to adapt immediately. No, he had actually measured a small evolutionary step in action: natural selection playing out over the course of a single field season.

Julia - Wow. I love the fact he took a leafblower with him and was like, "I'm gonna set up my own hurricane." This is why I love science.

Becky - It's the hotel room for me. What did he do? Put the 'do not disturb' sign out while he's there on the balcony?

Thor - I wonder what the people in the next room thought. It's one thing if someone has the TV on loud, but they're in there all day with a leaf blower!

Julia - You'd be like, "what is going on next door?" That is absolutely amazing.