Familiarity and gender influence social preferences in prairie voles (Microtus ochrogaster)

The physiological mechanisms influencing group cohesion and social preferences are largely unstudied in prairie voles (Microtus ochrogaster). In nature, prairie vole family groups usually consist of an adult male and female breeding pair, one or more litters of their offspring, and occasionally unrelated adults. Pair bonds, defined by heterosexual preferences, develop in male and female prairie voles following cohabitation or mating. However, social preferences between members of the same sex also may be important to the maintenance of communal groups. In the present study we compared the development of social preferences for conspecific strangers of the same sex versus preferences for the opposite sex, and examined the effect of the gonadal status of the stimulus animal on initial social preference. The present study revealed that reproductively naive males, but not females, showed initial preferences for partners of the opposite sex. In both sexes preferences for the opposite sex were not influenced by the presence or absence of gonadal hormones. Heterosexual and same-sex preferences for a familiar individual formed following 24 h of nonsexual cohabitation in both males and females. Male and female same-sex preferences, however, were no longer stable when the stranger in the preference test was of the opposite sex to the experimental animal. The development of same-sex preferences may help to maintain group cohesion, but same-sex preferences formed by cohabitation do not withstand the challenge of an opposite-sex stranger.