Fig. 2

Factors explaining differences between species in worker diversity. a Relationship between queen-worker dimorphism (log-transformed) and worker diversity (log-transformed standard deviation of head width) (N = 12 species). The phylogeny is based on ref. 18 and a generalized least squares model (GLS) assuming Brownian motion was applied. The best fit line is based on a linear regression through the origin based on phylogenetically independent contrasts (PICs). Queen-worker dimorphism explained 63% of the variation in worker size variation between species. b Relationship between colony size (log-transformed) and worker diversity (log-transformed standard deviation of head width) (N = 27 species). A GLS model revealed no relationship between colony size and worker diversity