Genomic targets of hurricane-induced selection on clinging performance in an island lizard

A central goal of evolutionary biology is to understand the molecular mechanisms that enable adaptive responses to novel environmental pressures. Extreme weather events like natural disasters can have catastrophic impacts on wildlife via habitat destruction, mortality,^1,2,3,4,5,6 population displacement,^6,7 and natural selection,^1,2,5,8,9 even shaping broad biogeographic patterns of local adaptation on phylogenetic scales.^10,11 However, few studies have investigated the functional changes in organismal performance or genomic targets associated with responses to such events.^2,12,13,14 Here, we investigate mechanisms of hurricane-mediated selection associated with parallel morphological shifts observed in a small island endemic lizard, the Silver Key Anole (Anolis scriptus), on two islands of the Turks and Caicos struck by hurricanes Irma and Maria in 2017.⁹ These observed changes suggest directional selection on clinging ability in the face of hurricane-force winds.^9,10,12,15 Genome scans for parallel selection identified five loci with known roles in musculoskeletal development and function. Among these loci, hs6st1 displayed the most significant genome-wide association with the length of the longest rear toe. CRISPR-induced knockout of hs6st1 resulted in significant toe length reduction and complete toe agenesis. Simulated high wind speeds revealed that shorter rear toe length was associated with greater clinging performance in anoles. This study highlights the interactions between performance, morphology, and genetic variation underlying rapid adaptive responses to extreme weather events in the wild. As extreme weather events become more frequent and severe in the coming decades,^16,17 understanding their evolutionary impacts will be critical for assessing their long-term effects on the world's biodiversity.¹⁸.