Climate change and the evolution of reef fishes: past and future

Predicting the impacts of ocean warming and acidification on marine ecosystems requires an evolutionary perspective because, for most marine species, these environmental changes will occur over a number of generations. Acclimation through phenotypic plasticity and adaptation through genetic selection could help populations of some species cope with future warmer and more acidic oceans. Coral reef species are predicted to be some of the most vulnerable to climate change because they live close to their thermal limits. Yet, their evolutionary history may indicate that they possess adaptations that enable them to cope with a high CO2 environment. Here, we first explore the evolutionary history of reef fishes and how their history has shaped their physiological adaptations to environmental temperatures and pCO(2). We examine current-day thermal and CO2 environments experienced by coral reef fishes and summarize experimental studies that have tested how they respond to elevated temperatures and pCO(2) levels. We then examine evidence for acclimation and adaptation to projected ocean warming and acidification. Indeed, new studies have demonstrated the potential for transgenerational plasticity and heritable genetic variation that would allow some fishes to maintain performance as the oceans warm and become more acidic. We conclude by outlining management approaches - specifically those that can help preserve genetic variation by maintaining population size - to enhance the potential for genetic adaptation to climate change.