Effects of Hurricane Strikes on Neotropical Lizard Morphology

The catastrophic damage caused by intense hurricanes can substantially affect the ecology of locations that they impact, including through natural selection of individual animals with the morphological characteristics suited to survive these extreme conditions. Anole lizards (Anolis scriptus and others) survive hurricanes by using their toepads to cling to surfaces during high winds. In a serendipitous study of A. scriptus on Pine and Water Cays in the Turks and Caicos Islands, Donihue et al. (2018) found that the populations that survived Hurricanes Irma and Maria (2017) had significantly larger body-size-corrected average toepad size than the populations surveyed immediately before the storms. These differences persisted when the A. scriptus populations were surveyed 18 months later, indicating that the anoles had passed the large relative toepad size trait to their offspring, and signifying a trans-generational effect of hurricane-induced natural selection.

The relationship between hurricane strikes and anole toepad size is also observed on longer spatial and larger temporal scales. For 12 populations of A. sagrei in the Bahamas and western Caribbean, the number of direct (within 30 km) strikes from hurricanes with maximum sustained winds of at least 41.1 m s^-1 (80 kt) during the period 1949-2017 were computed. A positive relationship was observed between number of hurricane strikes and body-size-corrected toepad area among the 12 independent populations. The same relationship was also examined for 171 anole species across the Caribbean and the Americas. A statistically significant positive correlation between number of hurricane strikes and body-size-corrected toepad size was also observed for this larger, multi-species dataset.

This is the first study to connect infrequent but severe selection events locally to trait diversity across clades and continents. Extreme climate events, which are intensifying due to climate change, can thus shape biogeographic and macroevolutionary patterns in ways that had previously been unsuspected for species in their path.