ABSTRACT
Evolution of life needs space and time. Additional large-scale drivers of diversifi cation are climate history, actual climate, and continental connectivity. Mountains represent a special case for all these drivers: Land area declines very rapidly with altitude-above the treeline, the global land area on average is halved every additional 167 m of altitude (Körner, 2007). Outside the tropics, the duration of the growing season also declines rapidly with altitude (less time available per year). Mountains also exhibit the most pronounced climatic gradients on earth, and glacial-interglacial cycles affected mountains more than most lowlands. Finally, mountains represent islands, archipelagos of high-altitude habitats, isolated from each other by valleys or lowlands, hence their species diversity should decline irrespective of other conditions, as is known from island biogeography (MacArthur and Wilson, 1967).
