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Social bonds between unrelated females increase reproductive success in feral horses


Cameron, EZ and Setsaas, TH and Linklater, WL, Social bonds between unrelated females increase reproductive success in feral horses, Proceedings of the National Academy of Sciences, 106, (33) pp. 13850-13853. ISSN 0027-8424 (2009) [Refereed Article]

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Copyright 2010 by the National Academy of Sciences

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DOI: doi:10.1073/pnas.0900639106


In many mammals, females form close social bonds with members of their group, usually between kin. Studies of social bonds and their fitness benefits have not been investigated outside primates, and are confounded by the relatedness between individuals in primate groups. Bonds may arise from kin selection and inclusive fitness rather than through direct benefits of association. However, female equids live in long-term social groups with unrelated members. We present 4 years of behavioral data, which demonstrate that social integration between unrelated females increases both foal birth rates and survival, independent of maternal habitat quality, social group type, dominance status, and age. Also, we show that such social integration reduces harassment by males. Consequently, social integration has strong direct fitness consequences between nonrelatives, suggesting that social bonds can evolve based on these direct benefits alone. Our results support recent studies highlighting the importance of direct benefits in maintaining cooperative behavior, while controlling for the confounding influence of kinship.

Item Details

Item Type:Refereed Article
Keywords:equid, friendship ,social structure, alliances, sociality
Research Division:Biological Sciences
Research Group:Ecology
Research Field:Behavioural ecology
Objective Division:Environmental Management
Objective Group:Terrestrial systems and management
Objective Field:Terrestrial biodiversity
UTAS Author:Cameron, EZ (Professor Elissa Cameron)
ID Code:67482
Year Published:2009
Web of Science® Times Cited:329
Deposited By:Zoology
Deposited On:2011-03-04
Last Modified:2011-03-17

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