To avert extinction in the face of climate change, species may disperse to track suitable habitat conditions as they shift in space, or evolve to adapt to the novel conditions.  These two processes may interact in important ways, for example if the arrival of a species pre-adapted to warmer local conditions fills a niche that a local species might otherwise evolve to fill.  To date, we have relatively little understanding of how dispersal-mediated species sorting and local adaptation interact to determine the overall biotic response to climate change.

Results/Conclusions

Here we use a theoretical model to evaluate how interactions between dispersal and local adaptation alter the distributions of species competing for space along a changing environmental gradient with and without climate change. We created a trait-based representation of a multi-species meta-community and allowed its numerical dynamics to play out along a linear spatial gradient under changing global temperatures. Under low adaptive potential (i.e., genetic variation) and along a gradient of increasing dispersal rate, model results show a shift from a situation where many species are specialized to narrow zones along the environmental gradient to a single generalist species spread across the entire gradient. At low dispersal ability and along a gradient of increasing adaptive potential, we find that species increasingly become adapted to larger spans of the environmental gradient. Without climate change, the highest number of effective species occurs with limited dispersal and adaptability. However, when climate change is introduced to the model, moderate levels of dispersal and adaptability are needed to maintain the most species in the system. Moreover, following a finite period of climate change, some species continue to become extinct during an extended time lag as the ecological and evolutionary dynamics play out in the context of the changed distribution of species and traits. Hence, moderate dispersal abilities and adaptabilities will be necessary to support existing species trait diversity under climate change and a significant “extinction debt” may occur even if climate change can be stopped.