We have over 12,000 students, from over 100 countries, within one of the safest campuses in the UK


93% of Lancaster students go into work or further study within six months of graduating

Home > Research > Publications & Outputs > Soay rams target reproductive activity towards ...
View graph of relations

« Back

Soay rams target reproductive activity towards promisculous females' optimal insemination period.

Research output: Contribution to journalJournal article


Journal publication date7/10/2003
JournalProceedings of the Royal Society B: Biological Sciences
Number of pages6
Original languageEnglish


Female promiscuity is thought to have resulted in the evolution of male behaviours that confer advantages in the sperm competition that ensues. In mammalian species, males can gain a post-copulatory advantage in this sperm 'raffle' by inseminating females at the optimal time relative to ovulation, leading to the prediction that males should preferentially associate and copulate with females at these times. To the best of our knowledge, we provide the first high-resolution test of this prediction using feral Soay sheep, which have a mating system characterized by male competition for access to highly promiscuous females. We find that competitive males time their mate guarding (and hence copulations) to occur close to the optimal insemination period (OIP), when females are also increasingly likely to 'cooperate' with copulation attempts. Subordinate males practice an alternative mating tactic, where they break the integrity of the consort pair and force copulations on females. The timing of these forced copulations is also targeted towards the OIP. We thus provide quantitative evidence that female promiscuity has resulted in the evolution of reproductive strategies in which males 'load' the sperm raffle by targeting their mating activity towards female OIPs, when the probability of sperm-competition success is at its greatest.