Genomic repeatability and predictability of local (mal)adaptation in a reef-building coral

Abstract

Climate change is a growing threat to biodiversity, and the persistence of populations largely depends on their capacity to adapt to changing environmental conditions. Although there is an urgent need to forecast local adaptive potential, it is unclear how such predictions are affected by the genomic architectures underlying local adaptation across a species range. In this study, we examine the genomic basis of local adaptation of the short-distance dispersing coral Stylophora pistillata, sampled at forty-six sites across eight reefs of the Great Barrier Reef, Australia. Our results show that thermal adaptation for this species involves hundreds of genomic loci with combinations that differ across geographic regions. Although adaptive loci were largely region-specific, genotype-environment relationships estimated across the entire range could predict regional-level adaptive patterns. This shows that genome-wide sequence data combined with geographically broad sampling can support reliable evolutionary forecasting. Under climate change projections, predicted shifts in genotype-environment associations were highly spatially variable, both between and within geographic regions. While some populations might be sufficiently adapted for moderate (SSP1-2.6 and SSP2-4.5) climate warming by 2050, up to 30% may face severe maladaptation risk by 2100 under a high-emission (SSP5-8.5) scenario. Collectively, these findings offer new insights into the spatial distribution of coral adaptive potential and how it might shape corals resilience in a warming ocean.