"Some guys have all the luck": mate preference influences paced-mating behavior in female rats.

In the present study, mating behavior was observed in female rats that were given the opportunity to mate with two males simultaneously. Three groups of females were tested: 1) sexually naïve, naturally cycling rats in proestrous; 2) sexually naïve, hormone-primed, ovariectomized (OVX) rats; and 3) hormone-primed, OVX rats tested 1 week after sexual receptivity testing. One male rat was determined to be the preferred male for each female, if she spent more time with him during a mating test. Independent of sexual experience, female rats were less likely to leave their preferred male than their non-preferred male following intromissions. However, when they left their preferred male, they returned to him faster than to their non-preferred male. This effect of preference was slightly more robust in the OVX rats. When female rats from Group 2 were tested with the same pair of males for 3 additional tests, each female's preference for a particular male was stable. That is, a female rat preferred the same male in approximately 3 out of the 4 tests, which is more likely than would be expected by chance. In a final experiment, pairs of male rats were tested with different females once weekly to determine if different females would prefer particular males consistently. Although no male rat was preferred by all females, females consistently preferred the same male from each pair during approximately 70% of the tests. In conclusion, female mate preference may have adaptive significance for the reproductive success of rats.