Editorial: Advances in Genomics and Epigenomics of Social Insects

The adaptive advantage of the eusocial lifestyle is evident from the fact that social insects represent more than half of the world's arthropod biomass. This topic explores how the recent advances in genomics and epigenomics are helping researchers to ask and answer questions concerning the evolution of social behavior and the genetic and epigenetic mechanisms behind phenotypic plasticity, i.e., how environmental signals can morph the same genome in a reproductive or non-reproductive individual resulting in dramatically different phenotypes. The articles in this research topic deal broadly with the evolution of reproductive and sterile castes (workers), mechanisms of caste determination, and the role of epigenetic processes for division of labor. The termites were the first group of insects to evolve eusociality and a thorough review describes what is known about the development of subcastes from a mechanistic perspective (nymphs, workers, soldiers) and the genomic contributions of gut symbionts and their hosts in digestion of wood, and the role of symbionts in host fitness (Scharf). Korb et al. compares the genomes of two termites with contrasting social complexities and symbioses. One of the interesting findings was that gene families involved in chemical communication in other social insects are not expanded in termites with more complex social organization. But transposable elements are, suggesting a role for transposition in social evolution but perhaps also pointing toward other mechanisms.