Signatures of selection underpinning rapid coral adaptation to the world's warmest reefs

Coral populations in the world's warmest reefs, the Persian/Arabian Gulf (PAG), represent an ideal model system to understand the evolutionary response of coral populations to past and present environmental change and to identify genomic loci that contribute to elevated thermal tolerance. Here, we use population genomics of the brain coral Platygyra daedalea to show that corals in the PAG represent a distinct subpopulation that was established during the Holocene marine transgression, and identify selective sweeps in their genomes associated with thermal adaptation. We demonstrate the presence of positive and disruptive selection and provide evidence for selection of differentially methylated haplotypes. While demographic analyses suggest limited potential for genetic rescue of neighboring Indian Ocean reefs, the presence of putative targets of selection in corals outside of the PAG offers hope that loci associated with thermal tolerance may be present in the standing genetic variation.

Automated summary

By studying the population genomics of the brain coral in the Persian/Arabian Gulf (PAG), researchers have found that the corals in the PAG represent a distinct subpopulation that was established during the Holocene marine transgression. The genomes of these corals contain selective sweeps associated with thermal adaptation. Although there is limited potential for genetic rescue of neighboring Indian Ocean reefs, there is hope that loci associated with thermal tolerance may exist in the standing genetic variation of corals outside of the PAG.