Lizard in an Evolutionary Tree's reworking of Williams' classic figure. Note that A. gundlachi is a trunk-ground anole, not, as indicated, a trunk-crown anole.
In this famous figure, Ernest Williams sketched out his view of how anole diversification occurred on the Greater Antilles, using Puerto Rico as an example. First, species diverge to use different structural habitat, producing the different ecomorphs. Subsequently, within-ecomorph divergence produces species that use the same structural habitat, but which occupy different climatic micro-climates, ranging from cool and moist rainforest to blazing hot and dry semi-desert. This two-stage pattern of evolution is displayed not only on Puerto Rico, but also on Cuba and Hispaniola (Jamaica, the most species deprived island, has little within ecomorph diversity).
In contrast to the plenitude of research in recent years on the adaptive basis of morphological differences among the ecomorphs, relatively little work has focused on the extent to which closely related species—members of the same ecomorph class—have adapted to occupying different microclimates.