Studies of pericopulatory pregnancy blockage and the gestation period in deer mice (Peromyscus maniculatus).
It has previously been shown that female deer mice in cycling estrus that copulate with or are exposed to more than one male at the time of mating have a lower probability of delivering a litter than when mating with and being exposed to just one male. In the present research the effect of post-mating exposure to the bedding of a strange versus a familiar male was studied in females in postpartum estrus. In four experiments females in postpartum estrus were protected from pericopulatory pregnancy blockage, presumably by suckling-induced elevated prolactin levels. Varying female experience, number of ejaculations, and the presence of suckling pups had no effect on this protection. Thus, both the pericopulatory block and the Bruce effect (a more delayed type of pregnancy blockage) occur in cycling, but not suckling, females. This suggests that the two may have a common mechanism and leads to a new perspective in the search for adaptive significance. In addition, the subsequent gestation periods were prolonged in females nursing young; the length was affected by the number of pups weaned from the previous litter and the number of pups being carried.
D000222:Adaptation, Physiological; D000818:Animals; D003307:Copulation / Q000502:physiology*; D005260:Female; D005849:Gerbillinae; D007247:Infertility, Female; D007774:Lactation; D008098:Litter Size; D051379:Mice; D010542:Peromyscus; D011247:Pregnancy; D011388:Prolactin / Q000502:physiology; D013045:Species Specificity
D011388:Prolactin