The origin and maintenance of montane diversity: integrating evolutionary and ecological processes

Determining how ecological and evolutionary processes produce spatial variation in local species richness remains an unresolved challenge. Using mountains as a model system, we outline an integrative research approach to evaluate the infl uence of ecological and evolutionary mechanisms on the generation and maintenance of patterns of species richness along and among elevational gradients. Biodiversity scientists interested in patterns of species richness typically start by documenting patterns of species richness at regional and local scales, and based on their knowledge of the taxon, and the environmental and historical characteristics of a mountain region, they then ask whether diversity – environment relationships, if they exist, are explained mostly by ecological or evolutionary hypotheses. Th e fi nal step, and perhaps most challenging one, is to tease apart the relative infl uence of ecological and evolutionary mechanisms. We propose that elucidating the relative infl uence of ecological and evolutionary mechanisms can be achieved by taking advantage of the replicated settings aff orded by mountains, combined with targeted experiments along elevational gradients. Th is approach will not only identify potential mechanisms that drive patterns of species richness, but also allow scientists to generate more robust hypotheses about which factors generate and maintain local diversity.