Genetic relatedness in groups of the humbug damselfish Dascyllus aruanus: small, similar-sized individuals may be close kin



    1. Integrative Ecology Group, Estación Biológica de Doñana, CSIC, Calle Américo Vespucio s/n, Sevilla 41092, Spain
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    1. IRD – UR128, Centre de Biologie et d’Ecologie Tropicale et Méditerranéenne, Université de Perpignan, 52 Av. Paul Alduy, F-66860 Perpignan cedex, France
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    1. Department of Psychology, Neuroscience and Behaviour, McMaster University, Hamilton, Ontario, L8S4L8, Canada
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    1. UMR 5244 EPHE/CNRS/UPVD, Université de Perpignan, F-66860 Perpignan Cedex, and UMS 2978 EPHE/CNRS, Centre de Recherches Insulaires et Observatoire de l’Environnement, BP 1013, Papetoai, Moorea, French Polynesia
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Peter M. Buston


Kin selection plays an important role in the evolution of social behaviour in terrestrial systems. The extent to which kin selection influences the evolution of social behaviour in marine systems is largely unexplored. Generally, it is considered that kin selection is irrelevant in marine systems, because it is assumed that the dispersing larval phase of marine organisms will break up kin associations. Here, we challenge this assumption and investigate the opportunity for kin selection in a coral reef fish: the humbug damselfish Dascyllus aruanus. This fish lives in groups composed of a large male and a number of smaller females and nonbreeders. We use 10 polymorphic microsatellite loci to assess the relatedness of 265 individuals from 35 groups. The mean coefficient of relatedness among group members is 0.01 ± 0.04, suggesting that individuals are not associated with close relatives. However, the distribution of pairwise relatedness of individuals within groups has an overabundance of positive values, and indicates that there might be 35 pairs of close relatives within groups. Further analyses reveal that close relatives likely are similar in size and small in size, suggesting that they might have recruited together. We conclude that it is possible for kin selection to operate in D. aruanus, but kin recognition will be a prerequisite for such selection. This study reveals that individuals can be associated with close relatives, and there is a hidden potential for kin selection, during certain parts of the life cycle of coral reef fishes.