Explaining negative kin discrimination in a cooperative mammal society
Proceedings of the National Academy of Sciences
National Academy of Sciences
Kin selection theory predicts that, where kin discrimination is possible, animals should typically act more favourably towards closer genetic relatives, and direct aggression towards less closely related individuals. Contrary to this prediction, we present data from an 18-year 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 behaviour, can benefit from much greater exploration of sequential social interactions
Funding was provided by a Natural Environment Research Council grant no. NE/J010278/1 to M.A.C. and A.J.Y. and a European Research Council grant no. 309249 to M.A.C
This is the author accepted manuscript. The final version is freely available from National Academy of Sciences via the DOI in this record.
Published online before print April 24, 2017