Population differences in aggression are shaped by cyclone-induced selection

Abstract Surprisingly little is known about the evolutionary impacts of rare but extreme black swan events, like tropical cyclones. By intercepting three cyclones in fall 2018, we evaluated cyclone-induced selection on collective behavior in a group-living spider. We further examined whether historic frequencies of cyclone landfalls are correlated with geographic variation in group behavior. Cyclones consistently selected for more aggressive spider societies. Furthermore, sites where cyclones have historically been more common also harbor more aggressive groups. Thus, two corroborative lines of evidence convey that that cyclone-induced selection can drive the evolution of colony behavior, and suggest that extreme black swan events can shape within-species diversity and local adaptation. One Sentence Summary Tropical cyclones drive the evolution of more aggressive spider societies.