Effects of Early Social Isolation upon Adult Timidity and Dominance in Peromyscus

Abstract

This investigation demonstrated that post-weaning social isolation has a differential effect upon adult dominance in two subspecies of wild deermice, Peromyscus maniculatus bairdii and Peromyscus maniculalus gracilis. Ten male bairdii reared together as a single group from weaning until 91 days of age were significantly more dominant in adulthood than bairdii reared in isolation. There was no difference in adult dominance between the social- and isolate-reared gracilis. Dominance was measured by pairing each social-reared mouse once with every isolate-reared mouse of the same subspecies in a series of 5-min. competitive drinking situations. These results further illustrate that the same form of early social experience can have a differential effect upon organisms of differing genotypes. There was no significant difference in timidity between social- and isolate-reared mice of either subspecies of Peromyscus.