This figure illustrates the central role of colony size in life history evolution of social insects. The flowchart depicts the influence of size-related
changes on the evolution of individual (in white) and group-level (in blue) life history traits. Dark blue arrows indicate causal relationships, which
are condition-dependent when lines are dotted. Colony size affected selective pressures are shown by large arrows, the colour of which indicate
the direction of selection (positive: green; negative: red). Colony size largely depends on worker production and worker lifespan, which in turn is
influenced by the extrinsic mortality of workers. Intra-specific and interspecific comparisons revealed an increase in division of labour, improved
resilience and colony defense, better resource holding potential and communication systems in larger social insect colonies. Although species with
stronger division of labour are likely to evolve morphological divergence within the worker caste, increased colony survival selects for colony
longevity and in turn for increased queen lifespan or queen replacement, for instance via secondary polygyny.