The causal role of odours in the development of recognition templates and social preferences

Despite decades of theoretical interest in the role of kin recognition in mate choice and nepotism, data on both the mechanisms and functions of recognition are available for only a few species. Even less common are demonstrations of direct causal links between the production and perceptual components of recognition and subsequent social preferences. Belding's ground squirrels, Spermophilus beldingi, produce odours that vary with kinship and can be used to discriminate classes of kin. However, the links between odours, recognition templates and differential treatment of conspecifics have not been shown empirically. Here I examined whether the manipulation of odour recognition templates influences juvenile behaviours. I induced recognition errors by exposing young to odours from a foreign mother before natal emergence. According to phenotype-matching mechanisms, developing young should incorporate all encountered odours into their kin template and later treat individuals matching the template as kin. As in previous studies, the most preferred play partners were littermates, but young also interacted preferentially with juveniles from the foreign family, whose odours were similar to the foreign mother and therefore matched their templates, compared with unfamiliar, unrelated juveniles. This preference for juveniles of the foreign family could not be due to relatedness or direct familiarity prior to emergence. Patterns of nasal investigations mirrored those of play bouts. This is a novel demonstration of a causal link between recognition cues, recognition templates and ‘kin’-differentiated behaviours, and highlights the potency of social odours during development on later social dynamics.