Community composition in mountain ecosystems: climatic determinants of montane butterfly distribution

Montane butterfly densities and species assemblages vary widely over space and through time. This variation is partially driven by variation in weather and climate, at spatial scales ranging from local habitats to regional ecosystems, and over time spans of days to centuries. We present case studies that illustrate how climatic variation affects individuals, population densities and species' ranges, and species distribution patterns at the regional level. Present patterns at all scales are neither spatially nor temporally static, even in the absence of directional anthropogenic climate change. The observed patterns allow us to sketch the broad outline of expected changes in population densites, species distributions and butterfly community composition under anthropogenic climate change. We conclude that the fragmented habitats found in montainous areas will exacerbate the effects of climate change on population densities and species' survival, and that relatively sedentary species require closer attention from conservation biologists.