Crawford Drury, Carlo Caruso, Kate Quigley

The decline of coral reefs has prompted an emergent field of research on the potential for various biological interventions focused on increasing stress tolerance in corals. Among these is selective breeding, the selection and reproductive crossing of parental stock based on a trait of interest with the goal of enhancing the frequency or intensity of the trait in subsequent generations. Selective breeding has been successfully applied to commercially and ecologically important species to mitigate the negative effects of climate change, including marine invertebrates and more recently, corals. Here, we review the process of selective breeding and detail 4 case studies that have documented the increase of thermal tolerance in selectively bred corals across various life history stages and temperature stressors. These outcomes are supported by a substantial body of literature demonstrating the heritability of thermal tolerance across organisms, including genome wide association studies and family-specific responses to heat stress in larvae. We also highlight some of the major knowledge gaps around selective breeding, including the magnitude of possible phenotypic tradeoffs and the potential for unintended negative genetic consequences, and discuss how these risks can be mitigated. We conclude by suggesting conservation approaches that can benefit from the integration of selective breeding. Current evidence suggests that selective breeding may be a viable option for supporting the persistence of coral reefs while climate action develops.