Rates of Embryonic Development of Sceloporus Lizards: Do Cold Climates Favor the Evolution of Rapid Development?

Abstract

Rapid embryonic development is a potential adaptation to cold climates. We tested this hypothesis for nine species of Sceloporus lizards from four species groups and one species of Urosaurus, an outgroup, using observations corrected for incubation temperature and hatchling size. Phylogenetically based comparisons indicated that relatively rapid development is characteristic of the scalaris species group and relatively slow development is characteristic of the undulatus species group. Comparisons within these lineages were therefore used to determine whether developmental rate was related to climate, as judged by elevation and latitude. Within the scalaris species group, developmental rates of cool climate populations of S. aeneus and S. scalaris were not faster than that of a warm climate population of S. scalaris. Within the undulatus species group, the developmental rate of cool climate populations or species were not faster than those of warm climate populations or species. In general, developmental rates of Sceloporus are lineage specific and do not appear to be adapted to local climates.