Abstract
Coral reefs are suffering a major decline due to the environmental constraints imposed by climate change. Over the last 20 years, three major coral bleaching events occurred in concomitance of anomalous heat waves, provoking a severe loss of coral world-wide. Recent works, however, reported of reefs at which recurrent bleaching events resulted in increased resistance to thermal stress, suggesting that adaptation might have occurred. The conservation strategies for preserving the reefs, as they are conceived now, cannot cope with global climatic shifts. In this regard, researchers advocated the set-up of a preservation framework to reinforce coral adaptive potential. The main obstacle to this implementation is that studies on coral adaption are usually hard to generalize at the scale of a reef system. In this work, we combined a seascape genomics and connectivity analysis to characterize the adaptive potential of a flagship coral species of the Ryukyu Archipelago (Japan). By associating genotype frequencies with descriptors of historical environmental conditions, we discovered six genomic regions hosting polymorphisms that might promote resistance against thermal stress. Remarkably, annotations of genes in these regions are consistent with molecular roles in heat responses. Furthermore, we confronted genetic distances between reefs with their spatial separation according to sea currents to predict connectivity patterns across the region. The cross-talk between the results of these analyses portrayed the adaptive potential of this population: we were able to identify reefs carrying potential adaptive traits and to understand how they disperse to neighbouring reefs. This information was summarized by objective, quantifiable and mappable indexes covering the whole region that can be extremely useful for prioritization in conservation plans. This framework is transferable to any coral species and on any reef system and therefore represents a valuable tool for empowering preservation efforts dedicated to the protection of coral reef in warming oceans.