Løvlie Hanne, Pizzari Tommaso
Department of Zoology, Stockholm University, Stockholm, Sweden.
Am Nat. 2007 Jul;170(1):E1-13. doi: 10.1086/518180. Epub 2007 May 22.
Selection on males to mate at a higher rate than females often results in male harassment of females and counteracting female responses. When the reproductive value of copulation changes over time, these mating strategies are expected to be time dependent. Here, we demonstrate that variation in the intensity of male harassment leads to drastic changes in female daily mating patterns. In feral populations of fowl Gallus gallus domesticus, male harassment is intense, particularly in the evening when inseminations are most likely to result in fertilization. We experimentally manipulated the intensity of male harassment through similar-sized groups of different sex ratios. Male mating propensity was always higher than females', particularly in male-biased groups and in the evening, when males were closer to and more likely to approach females. Females counteracted male harassment by escalating resistance to mating and--crucially--by shifting their daily mating pattern: in strongly female-biased groups with relaxed sexual harassment, females solicited sex in the evening, while in male-biased groups, they solicited sex in the morning, thus avoiding harassment in the evening. Together, these results indicate that intersexual conflict may occur not only over mating rates but also over when in the day to copulate.
选择让雄性比雌性以更高的频率交配，往往会导致雄性对雌性的骚扰以及雌性的反击。当交配的生殖价值随时间变化时，这些交配策略预计会随时间而变化。在这里，我们证明雄性骚扰强度的变化会导致雌性每日交配模式的剧烈变化。在家鸡（原鸡）的野生种群中，雄性骚扰很强烈，尤其是在晚上，此时受精的可能性最大。我们通过不同性别比例的相似规模群体，对雄性骚扰强度进行了实验性操纵。雄性的交配倾向总是高于雌性，特别是在雄性偏多的群体中以及晚上，此时雄性更接近雌性且更有可能接近雌性。雌性通过增强对交配的抵抗力来对抗雄性骚扰，关键是通过改变它们的每日交配模式：在性骚扰较轻的雌性偏多的群体中，雌性在晚上主动求偶；而在雄性偏多的群体中，它们在早上主动求偶，从而避免晚上受到骚扰。总之，这些结果表明，两性冲突不仅可能发生在交配频率上，还可能发生在一天中的交配时间上。
