The Evolution of Range Sizes in Mammals and Squamates: Heritability and Differential Evolutionary Rates for Low- and High-Latitude Limits

Species geographical ranges are at the core of many areas in evolutionary biology, yet empirical studies on the evolution of geographical ranges have been limited. Here, we integrate information on the phylogenetic relationships and geographical distribution of 3097 species of mammal (Artiodactyla, Carnivora, Chiroptera, Marsupialia, and Primates) and squamate (Anguimorpha, Gekkota, Iguania, Lacertoidea, Scincoidea, and Serpentes) to assess the degree of evolutionary “heritability” (i.e., phylogenetic autocorrelation) in range sizes and the extent to which range limits at higher and lower latitudes share similar evolutionary rates. Phylogenetic autocorrelation was highly variable among clades in the case of range size, but invariably high for range latitudinal centroid and range limits. Moreover, rates of evolution of high-latitude limits were 1.6–4 times faster than low-latitude limits. These results are consistent with previous experimental studies showing that heat tolerance is conserved across lineages, whereas tolerance to cold temperatures is more labile. The distinct evolutionary rates of low- and high-latitude limits has important implications for our understanding of the evolution of geographical ranges, as well as to understand how they could be affected by predicted anthropogenic climate changes.