LAUSR

Hurricanes are catastrophically destructive. Beyond their toll on human life and livelihoods, hurricanes have tremendous and often long-lasting effects on ecological systems1,2. Despite many examples of mass mortality events following hurricanes3–5, hurricane-induced natural selection has not previously been demonstrated. Immediately after we finished a survey of Anolis scriptus—a common, small-bodied lizard found throughout the Turks and Caicos archipelago—our study populations were battered by Hurricanes Irma and Maria. Shortly thereafter, we revisited the populations to determine whether morphological traits related to clinging capacity had shifted in the intervening six weeks and found that populations of surviving lizards differed in body size, relative limb length and toepad size from those present before the storm. Our serendipitous study, which to our knowledge is the first to use an immediately before and after comparison6 to investigate selection caused by hurricanes, demonstrates that hurricanes can induce phenotypic change in a population and strongly implicates natural selection as the cause. In the decades ahead, as extreme climate events are predicted to become more intense and prevalent7,8, our understanding of evolutionary dynamics needs to incorporate the effects of these potentially severe selective episodes9–11.Two populations of Anolis lizards that survived Hurricanes Irma and Maria had larger toepads, longer forelimbs and shorter hindlimbs relative to the pre-hurricane populations, which suggests hurricane-induced natural selection.