TY - JOUR

T1 - Soay rams target reproductive activity towards promisculous females' optimal insemination period.

AU - Preston, B. T.

AU - Stevenson, I. R.

AU - Wilson, Kenneth

PY - 2003/10/7

Y1 - 2003/10/7

N2 - 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.

AB - 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.

KW - Sperm Competition

KW - Promiscuity

KW - Mate Guarding

KW - Alternative Mating Tactic

KW - Soay Sheep

U2 - 10.1098/rspb.2003.2465

DO - 10.1098/rspb.2003.2465

M3 - Journal article

VL - 270

SP - 2073

EP - 2078

JO - Proceedings of the Royal Society B: Biological Sciences

JF - Proceedings of the Royal Society B: Biological Sciences

SN - 0962-8452

IS - 1528

ER -