Communicative diversity scales with social network structure in bottlenose dolphins

Social relationships can shape the demands placed on animal communication, but different dimensions of social organization may affect signal repertoires in different ways. We investigated whether variation in social network structure covaried with whistle repertoire organization in wild common bottlenose dolphins (Tursiops truncatus). We combined photo-identification and concurrent acoustic recordings across two field seasons, quantified group social topology and bond-strength structure, and characterized whistle repertoires using Hill diversity and continuous acoustic-distance metrics. Elastic-net models showed that groups with higher clustering coefficients had lower repertoire diversity, whereas mean and variable bond strength were associated with acoustic-distance structure. These relationships persisted after accounting for predominant behavioral state and group size. Our findings indicate that social cohesion and relationship heterogeneity correspond to distinct dimensions of communicative organization, supporting a multidimensional view of social and vocal complexity in fission-fusion societies.