ABSTRACT
The role of relatedness in animal societies has received important consideration as a process driving social groups. In the marine world, most studies which have investigated this question have focused on marine mammals such as whales and dolphins. For sharks, recent studies have demonstrated preferential associations among individuals from which social communities emerge. Assortment patterns have been found according to phenotypic or behavioural traits but the role of genetic relatedness and family structure in shaping the social structure of adult shark populations has never been investigated. Here, we used a social network analysis crossed with DNA microsatellite genotyping to investigate the role of the genetic relatedness in the social structure of a blacktip reef shark (Carcharhinus melanopterus) population. We found an established social network spatially organized but dynamic through time with different communities merging during the mating periods. Such recombination shows the males being more gregarious. Kinship was not a predictor of associations among sharks both at the dyad or community levels as individuals tended to associate independently and randomly regardless of the genetic relatedness between individuals. The lack of parental care in this species may contribute to the breakdown of family links in the population early in life, thereby preventing the formation of kin-based social networks.