Promising the future? Global change projections of species distributions

Projections of species' distribution under global change (climatic and environmental) are of great scientific and societal relevance. They rely on a proper understanding of how environmental drivers determine species occurrence patterns. This understanding is usually derived from an analysis of the species' present distribution by statistical means (species distribution models). Projections based on species distribution models make several assumptions (such as constancy of limiting factors, no evolutionary adaptation to drivers, global dispersal), some of which are ecologically untenable. Also, methodological issues muddy the waters (e.g. spatial autocorrelation, collinearity of drivers). Here, I review the main shortcomings of species distribution models and species distribution projections, identify limits to their use and open a perspective on how to overcome some current obstacles. As a consequence, I caution biogeographers against making projections too light-heartedly and conservation ecologists and policy makers to be aware that there are several unresolved problems. (c) 2006 Gesellschaft fur Okologie. Published by Elsevier GmbH. All rights reserved.