Mechanisms of social evolution from cockroaches to termites

The transition from solitary ancestral cockroaches to wood-feeding cockroaches exhibiting biparental care and termites displaying sibling altruism is closely linked to their ecological specialization in feeding on nutrient-poor dead wood. However, the underlying genomic evolutionary mechanisms remain unclear. To investigate this issue, the research team led by Sheng Li from South China Normal University conducted a multi-omics comparative analysis of genomes and transcriptomes across eight Blattodea species. They found that genomes progressively contracted during the evolution from cockroaches to termites. In wood-feeding cockroaches, the downregulation of genes associated with oxidative phosphorylation and peroxisomes constrained the growth and development rates of their offspring, which aligns with the observed slow larval growth. Termites, on the other hand, lost key genes involved in sperm motility, providing genomic support for the hypothesis that their reproductive division of labor is based on monogamy. Furthermore, termites achieved caste differentiation by co-opting nutrition-sensitive core developmental signaling pathways, such as juvenile hormone, insulin, epidermal growth factor receptor, and decapentaplegic (Dpp). This mechanism enables workers to exhibit high energy metabolism early in development to meet labor demands, while reproductive nymphs highly express energy metabolism-related genes later in development to ensure reproductive functions. This study systematically reveals the homeostatic maintenance mechanisms of termites as "superorganisms" and elucidates, at the molecular level, the evolutionary basis of social caste differentiation and energy allocation strategies.