University of Veterinary Medicine Vienna Philopatry yields higher fitness than dispersal in a cooperative breeder with sex-specific life history trajectories Social evolution is tightly linked to dispersal decisions, but the ecological and social factors selecting for philopatry or dispersal often remain obscure. Elucidating selection mechanisms underlying alternative life histories requires measurement of fitness effects in the wild. We report on a long-term field study of 496 individually marked cooperatively breeding fish, showing that philopatry is beneficial as it increases breeding tenure and lifetime reproductive success in both sexes. Dispersers predominantly join established groups and end up in smaller groups when they ascend to dominance. Life history trajectories are sex specific, with males growing faster, dying earlier, and dispersing more, whereas females more likely inherit a breeding position. Increased male dispersal does not seem to reflect an adaptive preference but rather sex-specific differences in intrasexual competition. Cooperative groups may thus be maintained because of inherent benefits of philopatry, of which females seem to get the greater share in social cichlids. en TEXT article Biased Dispersal; Cichlid Fish; Habitat Saturation; Broodcare Helpers; Delayed Dispersal; Group-Size; Ecological Constraints; Territory Quality; Reproductive Skew; Direct Benefits 2023 2023 Jungwirth, Arne (University of Veterinary Medicine, Vienna / University of Bern) Taborsky, Michael (University of Bern / Max Planck Institute of Animal Behavior / Institute for Advanced Study Berlin) Frommen, Joachim G (University of Bern / Manchester Metropolitan University) Josi, Dario (University of Bern / Eawag Swiss Federal Institute of Aquatic Science and Technology) Bonfils, Danielle (University of Bern) Zöttl, Markus (University of Bern / Linnaeus University) American Association for the Advancement of Science