GSE159973
Genetic toolkit for sociality predicts castes across the spectrum of social complexity in wasps
Here we reveal evidence of a shared genetic toolkit across the full spectrum of social complexity found in Vespid wasps, from simple group living where castes remain plastic throughout life, to complex superorganismal societies comprised of mutually dependent insects with irreversible castes determined during development. We generated brain transcriptomic data for castes in nine representative species; using a machine learning approach we identified thousands of shared orthologs which consistently describe castes (queens and workers), from species with the simplest (Mischocyttarus paper wasps) to the most complex (e.g. Vespine wasps) levels of social organisation. The top 400 genes were enriched in synaptic transport­­ genes, suggesting that these changes could affect brain neural function and connectivity. Fine-scale dissection of these patterns revealed that the molecular processes underpinning the simpler societies (which likely represent the origins of social living) are conserved throughout the major transition, but that additional processes may come into play in the more complex societies, especially at the point of no return where societies transition to be committed superorganisms. These analyses provide the first evidence of a conserved toolkit regulating social behaviour across the full spectrum of social complexity in any social insect. Importantly, they also provide evidence that there may be fundamental differences discriminating superorganismal societies from non-superorganismal societies. We suggest that the evolution of irreversible caste commitment (in superorganisms) is accompanied by a fundamental shift in the underlying regulatory molecular machinery; such shifts may also typify other major evolutionary transitions that are characterised by the emergence of a committed division of labour, such as the evolution of multicellularity.  Overall design: Whole brain RNA-Seq (pool of individuals)