Figure 2.

Socially monogamous prairie voles display several types of social behaviors that have been studied in laboratory conditions. (A) Photograph of a pair of male and female prairie voles with their pups in the nest. (B) Pair bonding behavior is measured using a 3-h partner preference test. The testing apparatus consists of three chambers connected by hollow tubes. At the beginning of the test, the subject is placed in the center cage and allowed to freely explore the other two cages containing either the partner or a conspecific stranger. (C) In both male and female prairie voles, 24-h cohabitation with mating reliably induces an increase in side-by-side contact with the partner versus a stranger, and this partner preference is not observed following 6-h cohabitation. (D) Selective aggression is another indicator of pair bonding. While sexually naïve males are not aggressive, pair-bonded males display aggression selectively toward stranger males and females, but not toward their partners. (E) Upon litter birth, both male and female prairie voles share the natal nest and engage in parental care. Data are shown as mean ± SEM. ^*P < 0.05. Alphabetic letters indicate the results from a post-hoc test following an ANOVA. Bars labeled with different letters differ significantly from each other. Data adapted, with permission, from (11, 102, 274, 283).