Elevational range size patterns of vascular plants in Himalaya contradict Rapoport’s rule

1. Elevational range size patterns reflect ecological and evolutionary processes, but they are also affected by geometric constraints. The confounding effect of these constraints led to an ongoing controversy about the elevational Rapoport’s rule, which postulates a positive association between the range size and elevation, and about the plausibility of the climate variability hypotheses as its causal explanation.

2. Here we used an advanced null modelling approach to disentangle the interacting effects of geometric constraints and species richness gradients on the elevational range size of vascular plants. We collected extensive field data on elevational distribution for 728 vascular plant species occurring in the Ladakh region, Western Himalaya. We supplied these regional data with sub-continental elevational ranges extracted from the literature. Moreover, we used in-situ measured temperatures to quantify temperature variability along an elevational gradient to test the climate var...