The rise of the ants: a phylogenetic and ecological explanation.

In the past two decades, studies of anatomy, behavior, and, most recently, DNA sequences have clarified the phylogeny of the ants at the subfamily and generic levels. In addition, a rich new harvest of Cretaceous and Paleogene fossils has helped to date the major evolutionary radiations. We collate this information and then add data from the natural history of the modern fauna to sketch a history of major ecological adaptations at the subfamily level. The key events appear to have been, first, a mid-Cretaceous initial radiation in forest ground litter and soil coincident with the rise of the angiosperms (flowering plants), then a Paleogene advance to ecological dominance in concert with that of the angiosperms in tropical forests, and, finally, an expansion of some of the lineages, aided by changes in diet away from dependence on predation, upward into the canopy, and outward into more xeric environments.