Extreme weather phenomena such as hurricanes and droughts can act as acute agents of natural selection, differing from the normal selective pressures affecting organisms. Being rare, such disruptions are thought to be temporary and not to have long-lasting evolutionary impacts.
Following hurricanes Irma and Maria in 2017, researchers paired a cross-generational and spatial approach to study potential evolutionary impacts on Caribbean anoles (Anolis scriptus). Initial investigations in the Turks and Caicos Islands found enlarged toe pads in post-hurricane lizards, thought to increase clinging performance—a useful trait during extreme winds.
When revisiting lizard populations 18 months later, they analysed hurricane survivor offspring and found that toepad size was unchanged, suggesting that trait shifts transcended generations. Broadening their focus, the authors sampled brown anoles (Anolis sagrei) across 12 Caribbean islands and found that hurricanes events in the past 70 years significantly predicted toepad size.
Expanding toepad analyses to the entire Anolis genus, the authors used GBIF-mediated occurrences and climate event data to quantify hurricane activity per species, finding a significant correlation between toepad size and hurricane activity. Together, these results show that extreme climate events can assert severe selective pressure with long-lasting evolutionary impacts.