As the climate warms, all species will either need to find new habitats with similar temperatures to those they currently occupy or evolve new thermal tolerances. Recent research by Araujo and colleagues suggests that some species may be able to adapt to new, higher temperatures better than others. Specifically, the authors analyzed the heat and cold tolerance capabilities of 2740 terrestrial ectotherm, endotherm, and plant species from across the globe. They found that maximum heat tolerance levels were similar across species, regardless of organism type, while maximum cold tolerance levels were more highly variable. This suggests that there is a physiological limit to heat tolerance across the tree of life. If so, species that already live in warm environments will likely be unable to effectively adapt to even warmer temperatures. In contrast, cold-adapted species will more easily be able to evolve higher heat tolerance and potentially survive. Thus, tropical species are likely at higher risk of extinction in the near term than temperate and polar species, a sobering thought given that a huge portion of the planet’s biodiversity is concentrated in tropical areas.
Araujo M, F Ferri-Yanez, F Bozinovic, PA Marquet, F Valladares, SL Chown (2013) Heat freezes niche evolution. Ecology Letters 16:1206-1219