Individual discrimination by odors in sibling prairie voles (Microtus ochrogaster)

The habituation-discrimination paradigm has been used widely to demonstrate that animals can detect individually distinctive odors of unfamiliar conspecifics. By using a modification of the habituation-discrimination technique, Todrank et al. (Anim Behav 55:377-386, 1998) found that golden hamsters discriminate between the individual odors of their own familiar brothers but cannot discriminate between the odors of two siblings that are unrelated and unfamiliar to the subject. This suggested that previous evidence showing that animals could discriminate between the odors of individuals actually may have demonstrated the ability to discriminate between genetically unrelated conspecifics (i.e., members of different families). To test this possibility, we conducted habituation-discrimination experiments with prairie voles, Microtus ochrogaster. Voles were tested under three conditions: subject and both targets were unrelated and unfamiliar; subject and both targets were brothers and familiar; subject was unrelated and unfamiliar to targets, but targets were brothers. In all cases, voles discriminated between the two individual odors. Thus, prairie voles can discriminate individual differences between the odors of brothers and they do not have to have previous experience with the conspecifics in order for discrimination to occur. The theoretical importance of these results is discussed.