Explaining negative kin discrimination in a cooperative mammal society

Faye J. Thompson, Michael A. Cant, Harry H Marshall, Emma I. K. Vitikainen, Jennifer L. Sanderson, Hazel J. Nichols, Jason S. Gilchrist, Matthew B. V. Bell, Andrew M. J. Young, Sarah J. Hodge, Rufus A Johnstone

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Kin selection theory predicts that, where kin discrimination is possible, animals should typically act more favorably toward closer genetic relatives and direct aggression toward less closely related individuals. Contrary to this prediction, we present data from an 18-y study of wild banded mongooses, Mungos mungo, showing that females that are more closely related to dominant individuals are specifically targeted for forcible eviction from the group, often suffering severe injury, and sometimes death, as a result. This pattern cannot be explained by inbreeding avoidance or as a response to more intense local competition among kin. Instead, we use game theory to show that such negative kin discrimination can be explained by selection for unrelated targets to invest more effort in resisting eviction. Consistent with our model, negative kin discrimination is restricted to eviction attempts of older females capable of resistance; dominants exhibit no kin discrimination when attempting to evict younger females, nor do they discriminate between more closely or less closely related young when carrying out infanticidal attacks on vulnerable infants who cannot defend themselves. We suggest that in contexts where recipients of selfish acts are capable of resistance, the usual prediction of positive kin discrimination can be reversed. Kin selection theory, as an explanation for social behavior, can benefit from much greater exploration of sequential social interactions.

© 2017, The Author(s). This is the final publishedversion of the article (version of record) uploaded in accordance with thepublisher’s self- archiving policy. It first appeared online via PNAS at http://www.pnas.org/content/114/20/5207. 

Original languageEnglish
Pages (from-to)5207-5212
JournalPNAS: Proceedings of the National Academy of Sciences
Issue number20
Early online date24 Apr 2017
Publication statusPublished - 16 May 2017
Externally publishedYes


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