TY - JOUR

T1 - Dispersal of sibling coalitions promotes helping among immigrants in a cooperatively breeding bird

AU - Sharp, Stuart P.

AU - Simeoni, Michelle

AU - Hatchwell, Ben J.

PY - 2008/9/22

Y1 - 2008/9/22

N2 - Kin selection is a major force in social evolution, but dispersal is often assumed to reduce its impact by diluting kinship. In most cooperatively breeding vertebrates, in which more than two individuals care for young, juveniles delay dispersal and become helpers in family groups. In long-tailed tits (Aegithalos caudatus), however, offspring disperse to breed and helpers are failed breeders that preferentially aid kin. Helping also occurs among immigrants, but their origins are unknown and cooperation in these cases is poorly understood. Here, we combine long-term demographic and genetic data from our study population to investigate immigration and helping in this species. We first used a novel application of parentage analysis to discriminate between immigrants and unknown philopatric recruits. We then cross-checked sibship reconstruction with pairwise relatedness estimates to show that immigrants disperse in sibling coalitions and helping among them is kin biased. These results indicate that dispersal need not preclude sociality, and dispersal of kin coalitions may help maintain kin-selected cooperation in the absence of delayed dispersal.

AB - Kin selection is a major force in social evolution, but dispersal is often assumed to reduce its impact by diluting kinship. In most cooperatively breeding vertebrates, in which more than two individuals care for young, juveniles delay dispersal and become helpers in family groups. In long-tailed tits (Aegithalos caudatus), however, offspring disperse to breed and helpers are failed breeders that preferentially aid kin. Helping also occurs among immigrants, but their origins are unknown and cooperation in these cases is poorly understood. Here, we combine long-term demographic and genetic data from our study population to investigate immigration and helping in this species. We first used a novel application of parentage analysis to discriminate between immigrants and unknown philopatric recruits. We then cross-checked sibship reconstruction with pairwise relatedness estimates to show that immigrants disperse in sibling coalitions and helping among them is kin biased. These results indicate that dispersal need not preclude sociality, and dispersal of kin coalitions may help maintain kin-selected cooperation in the absence of delayed dispersal.

KW - Aegithalos caudatus

KW - cooperative breeding

KW - dispersal

KW - immigration

KW - kin selection

KW - long-tailed tit

UR - http://www.scopus.com/inward/record.url?scp=48749107610&partnerID=8YFLogxK

U2 - 10.1098/rspb.2008.0398

DO - 10.1098/rspb.2008.0398

M3 - Journal article

VL - 275

SP - 2125

EP - 2130

JO - Proceedings of the Royal Society B: Biological Sciences

JF - Proceedings of the Royal Society B: Biological Sciences

SN - 0962-8452

IS - 1647

ER -