Figure 3

Relative residuals from best-fit regression models over the common size distribution of workers for thirteen Dorylus s.l . species in the different foraging niche categories. We distinguished between four categories of foraging niche: The surface swarm raiding Anomma driver ant species ("surface swarm"), the leaf-litter Anomma species ("leaf-litter"), the species that inherited subterranean foraging from the common ancestor of the genus Dorylus ("original subterranean"), and the Dorylus s.s. species that adopted subterranean foraging secondarily ("reversal subterranean"). Four key morphological traits were analysed: Maximum head width (HWmax), mandible length (ML), antennal scape length (SL), and hind leg length (HLL). Niche category had a significant effect on all traits (Nested ANOVA, p < 0.025 for all traits). Significant differences (Tukey's Studentized Range Test, p < 0.05) are indicated by different letters.