Genomic Comparison of the Ants Camponotus floridanus and Harpegnathos saltator

Ant Variation Ants of the same genotype can exhibit numerous phenotypic forms and develop multiple functional castes within a colony. Bonasio et al. (p. 1068) sequenced the genomes of two ant species exhibiting differences in caste development—Camponotus floridanus and Harpegnathos saltator—and used the sequences to compare gene expression and identify differences in epigenetic gene regulation that lead to the phenotypic differences. Ants may offer a model system for studying the role of epigenetics in behavior and development. Comparison reveals the epigenetic controls on caste development in ants. The organized societies of ants include short-lived worker castes displaying specialized behavior and morphology and long-lived queens dedicated to reproduction. We sequenced and compared the genomes of two socially divergent ant species: Camponotus floridanus and Harpegnathos saltator. Both genomes contained high amounts of CpG, despite the presence of DNA methylation, which in non-Hymenoptera correlates with CpG depletion. Comparison of gene expression in different castes identified up-regulation of telomerase and sirtuin deacetylases in longer-lived H. saltator reproductives, caste-specific expression of microRNAs and SMYD histone methyltransferases, and differential regulation of genes implicated in neuronal function and chemical communication. Our findings provide clues on the molecular differences between castes in these two ants and establish a new experimental model to study epigenetics in aging and behavior.