Figure 1. Laboratory characterization of mating-induced pair-bonding behavior.

(a) Photo depicts a pair-bonded male and female prairie vole displaying side-by-side (cuddling) contact (Photo by C. Badland & A. Smith). (b) In male and female prairie voles, 6 hrs of social cohabitation, without mating, is not sufficient to induce partner preference, as voles spend approximately an equal amount of contact time with their partner or with a stranger. Conversely, 24 hrs of cohabitation with successful copulation promotes partner preference formation, as voles spend significantly more time in side-by-side contact with their partner than with an unfamiliar stranger during a 3 hr partner preference assay. (c) Photo shows a pair-bonded male prairie vole (top) preparing to attack an unfamiliar stranger male prairie vole (bottom; Photo by C. Badland & A. Smith). (d) Sexually inexperienced (Naïve) male prairie voles do not display aggressive behavior toward a stranger, although successful mating and two weeks of social cohabitation engenders escalated selective aggression toward stranger male and female conspecifics but not toward familiar female partners. (e) Photo illustrates a pair-bonded male and female prairie vole huddling over and protecting their newly born pups (Photo by C. Badland & A. Smith). (f) Male and female prairie vole parents spend equivalent time in their natal nest huddling, contacting, and licking/grooming their offspring. Bars indicate means ± standard error of the mean. Bars with different Greek letters differ significantly from each other. *: p < 0.05. Adapted from [2,32^•,40,61].