How prior pair-bonding experience affects future bonding behavior in monogamous prairie voles.

Monogamous prairie voles (Microtus ochrogaster) form mating-based pair bonds. Although wild prairie voles rarely re-pair following loss of a partner, laboratory studies have shown that previous pairing and mating does not negate the ability to form a new partner preference. However, little is known about how prior bond experience may alter the trajectory and display of a new pair bond. In the present study, we disrupted an initial pair bond by separating partners and then varied the amount of time before a new partner was introduced. We assessed how separation time affected the stability of partner preference over time and influenced decision-making in male voles performing a head-to-head partner preference test in which they chose between the first and second partner. We found that the ability to consistently display a preference for the second partner, supplanting the initial pair bond, depended on how long the test animal was separated from their first partner. Prior bonding experience also shaped the subsequent effects of mating on partner preference. Partner preference strength was sensitive to latency to mate with the second partner but not the first partner, irrespective of separation time. These results suggest that the ability to form a consistent, strong preference for a new partner after an initial pair bond depends upon the amount of time that has passed since separation from the first partner. These results provide valuable insight into how social bonds are dynamically shaped by prior social experience and identify variables that contribute to recovery from partner loss and the ability to form a new pair bond. They also delineate a behavioral trajectory essential for future work examining the hormonal and genetic changes that enable recovery from partner loss.