Brain remodeling during queen maturation by a gene-regulation network that was co-opted by ants with reproductive workers

Developmental plasticity allows individuals to adapt to environmental conditions that vary predictably in space or time and thus to express distinct phenotypes from the same genomic information. In social insects, developmental plasticity during the immature stages results in caste differentiation or behaviorally distinct adults when conditions require the expression of different behaviors. Here, we investigated plasticity in brain morphology and transcriptomes when virgin gynes of the ant Monomorium pharaonis transition to functional queens after mating. Brains of gynes continuously increased after eclosion but this stopped after mating. Brain transcriptome comparison revealed a key genetic regulatory network triggered by mating that mediate the behavioral differences between the two phenotypes. The gene regulation network (GRN) mediating this reproductive transition appears to have been coopted by ant species with reproductive workers. Particularly the genes corazonin and neuroparsin-A, expressed in the anterior neurosecretory cells, showed consistently biased expression towards non-reproductive castes across ant species.