Effects of Extreme Climatic Events on Evolutionary Processes

Climate change, through its vast impacts on biodiversity, is one of the most-studied drivers of ecological change. Although reports of detrimental impacts of gradual global warming on the behavior and physiology of individuals, as well as on populations and communities are now common in scientific literature, much less is known about the impact of extreme climatic events (ECEs) on evolutionary processes. In this review, we provide a broad overview of the state of knowledge on ECEs in the context of evolution. We begin by discussing the drivers of evolution (i.e., mutation, selection, gene flow, and genetic drift) and how ECEs may impact them. We then discuss why rapid adaptation and evolutionary rescue in response to ECEs will be hindered in many species, due to the unpredictable nature and timing of these events. We further outline that potential changes in evolutionary processes in response to ECEs can be better understood by recognizing shifts in ecological interactions, emphasizing the connected nature of communities and ecosystems and the evolutionary consequences. We finally highlight that there is a clear gap in our knowledge of ECE impacts, particularly at the genetic level. In order to understand the relationships between climate change, ECEs, and evolutionary processes, we urgently need hypothesis-driven monitoring efforts and studies that investigate existing data through the lens of historically documented ECE events. Taken together, our review highlights that extreme climatic events associated with climate change are undermining biodiversity through diverse pathways, and that the prospects for rapid adaptation and evolutionary rescue are severely constrained by a host of ecological and genetic challenges.