Dr Emily Howells

The persistence of reef-building corals is dependent on evolutionary responses to climate change. Yet, it remains uncertain whether populations have already adapted to recent warming (+0.6 °C since 1980) and if their adaptive capacity is sufficient to keep pace with additional rapid warming predicted over the coming decades (+1–3 °C by 2081–2100 relative to 1995–2014). Much of this uncertainty is due to limited knowledge of adaptive genetic variation in coral host populations, that is, the differences among the genomes of individuals which influences coral phenotypes and their fitness. Selection on adaptive genetic variation can enable populations to evolve tolerance to changing environments beyond the limits of phenotypic plasticity. Therefore, understanding the extent of adaptive genetic variation within populations and its distribution across the seascape is critical for monitoring and predicting responses to selective pressures imposed by climate change. Identifying specific genomic variants associated with thermal tolerance traits can also reveal genes and biochemical pathways involved in cellular stress and coral bleaching, and comparative studies can determine whether these variants underpin shared mechanisms of tolerance across populations and species. Furthermore, information on adaptive genetic variation can support management strategies for coral reefs by incorporating evolutionary potential into resilience frameworks, spatial planning, and the selection of corals for restoration and adaptation interventions. This chapter reviews the current state of knowledge, information gaps, and approaches for identifying, monitoring, and managing adaptive genetic variation with a focus on improving the understanding of the evolutionary responses of reef-building corals to climate warming.