TY - JOUR

T1 - Kinship affects investment by helpers in a cooperatively breeding bird

AU - Nam, Ki-Baek

AU - Simeoni, Michelle

AU - Sharp, Stuart P.

AU - Hatchwell, Ben J.

PY - 2010/11/7

Y1 - 2010/11/7

N2 - Helping behaviour in cooperative breeding systems has been attributed to kin selection, but the relative roles of direct and indirect fitness benefits in the evolution of such systems remain a matter of debate. In theory, helpers could maximize the indirect fitness benefits of cooperation by investing more in broods with whom they are more closely related, but there is little evidence for such fine-scale adjustment in helper effort among cooperative vertebrates. In this study, we used the unusual cooperative breeding system of the long-tailed tit Aegithalos caudatus to test the hypothesis that the provisioning effort of helpers was positively correlated with their kinship to broods. We first use pedigrees and microsatellite genotypes to characterize the relatedness between helpers and breeders from a 14 year field study. We used both pedigree and genetic approaches because long-tailed tits have access to pedigree information acquired through social relationships, but any fitness consequences will be determined by genetic relatedness. We then show using both pedigrees and genetic relatedness estimates that alloparental investment by helpers increases as their relatedness to the recipients of their care increases. We conclude that kin selection has played a critical role in moulding the investment decisions of helpers in this cooperatively breeding species.

AB - Helping behaviour in cooperative breeding systems has been attributed to kin selection, but the relative roles of direct and indirect fitness benefits in the evolution of such systems remain a matter of debate. In theory, helpers could maximize the indirect fitness benefits of cooperation by investing more in broods with whom they are more closely related, but there is little evidence for such fine-scale adjustment in helper effort among cooperative vertebrates. In this study, we used the unusual cooperative breeding system of the long-tailed tit Aegithalos caudatus to test the hypothesis that the provisioning effort of helpers was positively correlated with their kinship to broods. We first use pedigrees and microsatellite genotypes to characterize the relatedness between helpers and breeders from a 14 year field study. We used both pedigree and genetic approaches because long-tailed tits have access to pedigree information acquired through social relationships, but any fitness consequences will be determined by genetic relatedness. We then show using both pedigrees and genetic relatedness estimates that alloparental investment by helpers increases as their relatedness to the recipients of their care increases. We conclude that kin selection has played a critical role in moulding the investment decisions of helpers in this cooperatively breeding species.

KW - CARRION CROWS

KW - helper

KW - kin selection

KW - FAIRY-WRENS

KW - LONG-TAILED TITS

KW - long-tailed tits

KW - provisioning effort

KW - kinship

KW - KIN SELECTION

KW - indirect fitness

KW - LIFE-HISTORY

KW - SEYCHELLES WARBLER

KW - INDIRECT FITNESS BENEFITS

KW - HELPING-BEHAVIOR

KW - AEGITHALOS-CAUDATUS

KW - EVOLUTION

U2 - 10.1098/rspb.2010.0737

DO - 10.1098/rspb.2010.0737

M3 - Journal article

VL - 277

SP - 3299

EP - 3306

JO - Proceedings of the Royal Society B: Biological Sciences

JF - Proceedings of the Royal Society B: Biological Sciences

SN - 0962-8452

IS - 1698

ER -