Project description: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.
Project description:Parasitoid wasps of the species Diachasmimorpha longicaudata are associated with a heritable poxvirus, known as DlEPV, that is stored in the venom gland of adult female wasps and transferred to tephritid fly hosts of the wasps during oviposition. We conducted a RNA-seq differential expression analysis to gain insight on how DlEPV can replicate in both wasps and their fly hosts but only cause pathogenic effects during replication in flies. Our analysis revealed that 91.2% (176 of 193) of DlEPV genes showed significant differential expression during peak virus replication in wasp venom glands compared to parasitized flies. Over 80% of DlEPV replication genes were significantly upregulated in wasps, while 79% of DlEPV putative virulence genes were significantly upregulated in fly hosts. These data therefore support a dichotomy of viral function, where virus replication is promoted in wasp tissue and virulence in host tissue. Such a division of viral activity could represent an important adaptation to maintain a stable symbiosis between this virus and its associated parasitoid.
