Sperm Competition and Optimal Timing of Matings in Microcebus murinus

Abstract

Female promiscuity is common in mammals and leads to sperm competition: the sperm of ≥2 males compete for ova. Scientists understand the possible role of optimal insemination periods for male reproductive success in many species as well as the impact of monopolization of receptive females. Information from experiments combined with detailed observations from the field that allow determining the relative impacts of the elements in the same species are rare. We studied sperm competition and the role of optimal insemination periods in gray mouse lemurs (Microcebus murinus), a small solitary nocturnal primate from Madagascar. We used controlled matings to identify the relative impact of both contest and scramble competition, which characterize their mating system, on paternity. Fifteen females mated with 3–6 males in quick succession. Our experiments revealed that the optimal insemination period is during early receptivity. Early but not first mating males are more likely to sire offspring. Comparison with our field data indicate that the timing of male monopolization efforts correspond with the optimal insemination period.