Postejaculatory quiescence in female and male rats: Consequences for sperm transport during group mating.

Abstract

During mating in a multimale-multifemale group, female rats (Rattus norvegicus) had a quiescent period following each ejaculation, which was comparable with the males'' (a postejaculatory interval or PEI). The PEIs of both sexes were characterized by 3 behaviorally distinguishable phases: a stationary phase, an interactive phase, and a sexual phase. In these particular groups, there was no significant sex difference in the total length of the PEI (P = 0.325; log-survivor analysis was used for all temporal events) but females began active sexual behavior and entered the sexual phase more quickly than males did (P = 0.007). The time course of each phase of the PEI is compared with the time course of sperm transport in the Sprague-Dawley female, and the similarities and differences between the 2 sexes'' reproductive strategies following an ejaculation are emphasized.