Fission–Fusion

“Fission–fusion” was introduced to describe the social system of species that change group size by means of the fission and fusion of subgroups according to their activities and the availability and distribution of resources. The term “fission–fusion dynamics” was proposed to refer to the extent of variation in spatial cohesion and individual membership in a (sub)group over time. Any animal social system can be characterized by its degree of fission–fusion dynamics, varying from highly cohesive with fixed membership to highly fluid with flexible membership. Fission–fusion dynamics have important implications because they influence the opportunities for group members to interact with one another. Phylogenetic comparative studies can examine the socioecological factors affecting the degree of fission–fusion dynamics, as well as whether different degrees of fission–fusion dynamics create specific challenges and opportunities for social interactions and distinct selective pressures for specific underlying communicative signals, cognitive abilities, and collective decision mechanisms.