On metapopulations and microrefugia: palaeoecological insights

We highlight the importance of microrefugia in the light of population migration and genetic drift by synthesizing lessons learnt from metapopulation and palaeoecological studies. The concept of microrefugia is considered as a long-term variant of conventional metapopulations, in which microclimatic stability supersedes gene flow in determining species survival. Not all species can maintain populations in microrefugia. Life history traits such as small body size, the capacity for asexual reproduction, and species with light genetic loads favour survival. Microrefugia will facilitate faster rates of species responses to climate change than envisioned in diffusion models, and potentially provide a means to alleviate the negative effects posed by natural or anthropogenic barriers to migration. Predictive models based on relatively coarse-grained approaches that ignore microrefugia will lead to overestimates of extinction risk. Microrefugia should be identified and conserved, not for the species they contain, as these are likely to turn over with time, but as an important component of landscape diversity that will provide a safe haven for species not yet identified as at risk.