Social interactions, cross-fostering, and sibling recognition in prairie voles, Microtus ochrogaster

Sibling recognition in prairie voles (Microtus ochrogaster) has been traditionally inferred from incest avoidance or lack of reproduction among littermates. Researchers have concluded that when sibling prairie voles are isolated from one another there is a breakdown of incest avoidance (and therefore of sibling recognition). In a reevaluation of these studies, using social interactions rather than incest avoidance, we found that the breakdown of incest avoidance was not equivalent to a breakdown of sibling recognition. We explored the effects of cross-fostering on sibling recognition by looking at changes in amicable or agonistic behaviors that were then used to infer sibling recognition. Prairie voles that were cross-fostered with nonsiblings were not able to recognize their own siblings when reunited and tested for social interactions in adulthood. Siblings reared apart treated their own siblings as if they were not closely related and nonsiblings reared together treated nonsiblings as if they were their own siblings. The mechanism of sibling recognition in prairie voles is association or familiarity. The ability to recognize siblings may be limited to individuals that are raised together. Sibling recognition in prairie voles may be a by-product of familiarity in early life and not a mechanism restricted to genetic relatedness as predicted by kin-selection theory.