Genetic relatedness in social groups of the emerald coral goby Paragobiodon xanthosoma creates potential for weak kin selection

The explanation for why animals form social groups that include breeders and non-breeders is an evolutionary puzzle with some parts yet unsolved. Ecological constraints explain why non-breeders do not disperse to breed on their own, while social constraints explain why they do not contest to breed at home. Often kin selection explains why non-breeders behave cooperatively. Originally kin selection was assumed to play no role in social evolution in organisms with dispersive larval phases, such as many marine organisms. However, recent evidence suggests small-scale patterns of relatedness in some marine animals, which may influence behavior. To understand the relevance of kin selection in marine fishes, it is first necessary to examine relatedness patterns within groups. We, therefore, investigated the genetic structure of social groups of the emerald coral goby, Paragobiodon xanthosoma, for which kin selection has been assumed to play a minimal role in its social evolution. We genotyped ...