Kin recognition in golden hamsters: Evidence for phenotype matching

We assessed' scent marking by golden hamsters in response to flank gland odours from kin and nonkin to investigate mechanisms of kin recognition by odour cues. Hamsters engage in two types of scent-marking behaviour, flank marking, which is associated with competition and aggression, and vaginal marking, which females use for sexual solicitation. In experiment 1, flank marking by males and flank and vaginal marking by females was significantly less in response to flank odours from siblings than nonsiblings. These results indicate a lower level of agonistic motivation(flank marking) and sexual interest (vaginal marking) towards kin than nonkin. In experiment 2, the marking responses of males and females to flank odours from siblings, unfamiliar half-siblings and unfamiliar nonsiblings were graded based on the degree of relatedness. In experiment 3, males from cross-fostered litters marked significantly less in response to flank odours from brothers than nonbrothers, regardless of whether they were reared with the odour donors. These results demonstrate a phenotype matching mechanism for kin recognition based on differences between odours from kin and nonkin. Because the presence of foster-siblings or a foster- mother in the nest did not change hamsters' responses to flank odours from kin versus nonkin, one possible explanation for our results is that hamsters use their own odour as a referent in this process ('self-referent phenotype matching').