Evolution of leader-follower role in termite tandem runs

Group-living animals coordinate their movement while migrating as a group. Tandem running in termites is the simplest movement coordination that involves leader–follower relationships. Unlike ants, a tandem run of termites is performed by mating pairs while seeking sites for colony foundation. In Reticulitermes and Coptotermes termites, the leader role is fixed in females in heterosexual pairing, and movement coordination is achieved through adjusting movement speed to the distance to each other. In this presentation, we show how they evolved such a fixed leader-follower relationship during tandem runs. First, we found that both females and males have the behavioral potential to perform both leader and follower roles. In a same-sex pairing context, one partner adopts the other sex’s movements to maintain same-sex tandem runs. Second, a systematic literature survey and phylogenetic comparative analysis suggest that the ancestors of modern termites lack consistent sex roles during pairing. This indicates that behavioral flexibility was inherited from an ancestral lineage. Finally, comparative behavioral analysis suggests that a fixed female-leader role in heterosexual pairing is associated with the evolution of strong sexual pheromones. Thus, signal communication plays a vital role in the evolution of movement coordination.