The evolution of foraging niche in Dorylus s.l . army ants. The most parsimonious reconstruction of the evolutionary transitions is illustrated by different branch colours, while the Bayesian reconstruction with the highest posterior probability is indicated with coloured rectangles at the relevant nodes. Age estimates (clocks) for key nodes are given in million years ago (mya), after fixing the most recent common ancestor of Dorylus s.l. at 45.6 mya ; see text for ranges. The phylogeny was obtained by Bayesian analysis of a dataset from which males had been excluded. Subgenera are abbreviated as in Fig. 1. Photographs to the right depict workers of representative species with different foraging niches and illustrate the differences in relative leg length, mandible length, and antennal scape length associated with the three foraging niches (all pictures are the same scale and all workers have a maximum head width of 2.27 mm; from top to bottom: 1. D. (An.) arcens (surface swarm raiding), 2. D. (An.) gerstaeckeri (leaf-litter), 3. D. (Do.) affinis (reversal subterranean) 4. D. (Ty.) sp. 1 (original subterranean).