Detecting refugia from climate change based on colonization, local extinction and changes to community composition

As the climate changes, we expect species geographic ranges to shift to higher latitudes and elevations, and ecological communities to be composed increasingly by warm- or dry-adapted species. Recent changes to species distributions and diversity have been broadly consistent with these expectations, but delays or deviations from the general trends are informative in understanding ecological responses to climate change. Importantly, climatic conditions do not change gradually over time or space: cool years are interspersed with hot years, different seasons and weather variables show different trends, and different environments warm or dry at different rates. As a result, recent rates of range expansion, local extinction and changes to community composition have been faster in some environments than others. Here, I illustrate the influence of topography, microclimate and land cover on colonization, local extinction and the distributions and community composition of butterflies (and some plants and beetles), using examples from two contrasting regions: England, where many species reach high-latitude range margins; and the Iberian Peninsula, where many species are limited to mountains at low-latitude range limits. The results suggest that microclimatic or topographic variability can buffer species against negative impacts of warming, suggesting a possible role in conservation for topographically variable landscapes as refugia from climate change