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Co-operative breeding in vertebrates may emerge due to subordinates delaying dispersal when free breeding habitat is not available (‘habitat saturation’ hypothesis, HS). However, delayed dispersal might also be due to younger individuals postponing dispersal to when they are more competitively able or have more to gain from breeding independently (“benefits-of-philopatry” hypothesis, BP) or to when inclusive fitness benefits no longer outweigh the benefits from independent breeding (“kin selection” hypothesis, KS). Here, we show in three experiments that both HS and BP determine the extent of co-operative breeding in the cichlid Neolamprologus pulcher. Contrary to the KS, individuals significantly avoided settlement with related individuals, and an additional settlement experiment confirmed this result. Our results suggest that kin structure in these cichlids emerges from limits on dispersal, but if such …