Rates of upslope shifts for tropical species depend on life history and dispersal mode

Abstract

The recent paper by Freeman and Class Freeman (1) adds to a growing body of literature documenting the upslope distributional shifts of tropical montane species in response to climate change. Armed with just a handful of studies from the tropics, the authors compare upslope shift rates between tropical and nontropical species and conclude that tropical species are, on average, shifting their distributions faster than temperate species. On the basis of this broad comparison, the authors contend that tropical montane species are more sensitive to temperature changes than are temperate species. Although this is a laudable first attempt to synthesize basic patterns of range shifts in tropical species, I believe that the authors drew spurious conclusions because they overlooked some basic ecological differences between taxa.