Navigating flooded roads and downed power lines, Pruitt often relied on chainsaw-wielding locals to cut a path for him. “They’d begin dismantling fallen trees before FEMA ever showed up, literally carving a way back to my sites,” he says. “Some I couldn’t get back to because of flooding. Those we figure have been submerged and swept away.”
But the ones that did survive, he tallied up. And to those sites he returned two more times, months later, to count how many eggs had been produced and how many spiderlings hatched. What he discovered was that colonies that had been more aggressive pre-cyclone had more babies, and more of those juvenile spiders ended up surviving, in the aftermath of each storm. To see if this was a longer-term trend, Pruitt’s team compared 13 study sites from Louisiana up to North Carolina with a century’s worth of cyclone strike data. They found that the most aggressive colonies were located in places with the highest historic exposure to cyclones.
“There’s clearly some kind of selection going on here for the aggressive individuals in response to these extreme weather events, and that’s what’s really fascinating,” says George Uetz, a spider biologist at the University of Cincinnati. Though not involved in the study, he was the one who, many years ago, invented the method Pruitt used for stimulating a spider’s web. Except that back then electric toothbrushes hadn’t yet been invented, so he used a vibrator instead. “I got a lot of teasing for that,” says Uetz.
In the wolf spiders he studies, he’s observed hints of a similar phenomenon; after a tornado smashed through an Ohio nature preserve, males born in the blowdown zones for generations after had smaller, less attractive claw tufts, making it harder for them to find mates. But he’s never seen anything like a storm changing the long-term behavior of a whole species.
“On the one hand, it’s not surprising that natural disasters have an impact on the survival of animals,” he says. “But to see their impact on selection, how they actually drive the direction of evolution in a species is pretty rare.”
The studies might be few and far between, but Pruitt suspects the phenomenon is more widespread. That’s why he spent the last seven weeks driving 22,000 miles through the bayous and lowlands of the Gulf coast, working 14-hour days setting sticky card traps and gathering thousands of vials of antifreeze-suspended insects with just his Australian shepherd-Border collie mix, Winifred Sanderson, to keep him company.
Even as someone who grew up in a hurricane-smacked “hick portion” of central Florida, Pruitt wasn’t always prepared for what he came across. More than once, while driving through miles of sugar cane stands, he says he has come across armed poachers loading freshly trapped reptiles into terrarium-lined truck beds. “I tried to just look as Canadian as possible,” he says. “Like, ‘Hi,‘I’m just here collecting INSECTS!’”
His ultimate goal is to see what sorts of species do well in the aftermath of hurricanes. Do such storms allow invasive species like red fire ants to get an edge over native animals? Or do they fare worse because they haven’t evolved in a hurricane-pummeled environment? What about species of mosquitoes that carry human diseases versus those that don’t? “The question is how important are these extreme events in maintaining trait diversity,” says Pruitt. “Clearly something very special is happening.”
Understanding exactly how species are evolving in response to disturbances from extreme weather is more urgent now than ever. As the planet continues to warm, scientists project that hurricanes will intensify, heatwaves will get hotter, and droughts will grow longer. You probably know from Ian Malcolm’s mansplaining of chaos theory in Jurassic Park that the flap of a butterfly’s wing in Brazil can kick off a tornado in Texas or a hurricane in North Carolina. Now we know—at least for spiders—the relationship works both ways.