Using social network analysis to confirm the 'gambit of the group' hypothesis for a small cetacean.

Social network analysis (SNA) can be used to explore a population's social structure and how individuals contribute to social cohesion. Quantifying relationships between individuals in a network can vary depending on the data available or the relationship of interest. Studies of readily visible species can use direct interaction measures in SNA, while studies of cryptic species usually rely on the 'gambit of the group'; individuals observed in a group are considered associates. This study compared the association and pectoral fin contact (PFC) networks of Atlantic spotted dolphins around Bimini to test the 'gambit of the group' hypothesis. The association network had nearly three times as many edges than the PFC network. Still, the two networks were correlated; individuals with a relationship in one network had a comparable relationship in the other. Many network measures were also correlated across networks, suggesting association is an acceptable substitute for physical interaction in certain cases. The current study supports the 'gambit of the group', but also highlights the importance of considering what types of relationships are used in the analysis of the social system of the focal species.