The role of prolonged copulatory behavior in facilitating reproductive success in male Syrian golden hamsters (Mesocricetus auratus) in a competitive mating situation

Abstract

1. The objective of this research was to determine whether the multiple ejaculation pattern of golden hamsters might have a functional consequence in increasing the percentage of offspring sired by a male when the female partner subsequently mates with a second male. 2. A risk of displacement by a second male was demonstrated to exist. When two male hamsters mated for five ejaculatory series each, a male was able to sire significantly more offspring when mating second than when mating first. Thus, hamster compulatory plugs do not provide complete protection against subsequent sperm displacement. 3. Prolonged copulation can provide protection against sperm displacement. Prolongation afforded no protection to cream males. However, when agouti males mated to satiety prior to a mating by a cream male, the agouti males sired more of the offspring than when they attained just one or five ejaculations. 4. The primary mechanism underlying the protective effects of prolongation of copulation was found related to copulations with sperm transfer, presumably stemming from the relative concentrations of sperm from the two males. Neither the mere passage of time nor copulation by a vasectomized male conferred a protective effect. 5. Viewed as a reproductive strategy in social context, the multiple ejaculatory pattern can be seen as having functional significance in maximizing individual fitness.