The Risk and Intensity of Sperm Ejection in Female Birds
The Risk and Intensity of Sperm Ejection in Female Birds
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DOI：
10.1086/661244
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发表时间：
2011-09-01
影响因子：
2.9
通讯作者：
Pizzari, Tommaso
中科院分区：
文献类型：
--
作者：
Dean, Rebecca;Nakagawa, Shinichi;Pizzari, Tommaso
雌性利用不同雄性配子的方式对自然群体中的性选择、性冲突和两性共同进化具有重要影响。然而，雌性精子利用的模式很难证明，其功能意义仍不清楚。在这里，我们对家鸡的精子喷射进行了实验研究，其中雌性优先喷射社会上处于从属地位的雄性的精子。我们研究了精子射出的两种衡量标准，（i）射精的概率（“风险”）和（ii）射精的比例（“强度”），并表明这两种衡量标准对于射精、男性和女性的特征来说都是非随机的。精子射出平均会中和 80% 的射精，虽然射精量较大的射精风险较高，但射精量较小的射精会更强烈。在控制射精量后，我们发现社会地位较低的男性的射精强度更高。在控制了雄性和射精效应后，我们发现，随着雌性与连续雄性交配，射精风险增加，强度下降。总的来说，这些结果表明，精子射出风险和强度至少部分是由女性行为主动引起的，并对男性和射精表型产生独立的选择压力。
The way females utilize the gametes of different males has important consequences for sexual selection, sexual conflict, and intersexual coevolution in natural populations. However, patterns of sperm utilization by females are difficult to demonstrate, and their functional significance remains unclear. Here, we experimentally study sperm ejection in the fowl Gallus gallus domesticus, where females eject preferentially the sperm of socially subordinate males. We study two measures of sperm ejection, (i) the probability that an ejaculate is ejected ("risk") and (ii) the proportion of semen ejected ("intensity"), and show that both measures are strongly non-random with respect to characteristics of the ejaculate, the male, and the female. Sperm ejection neutralized on average 80% of an ejaculate, and while larger ejaculates suffered a higher ejection risk, smaller ejaculates suffered more intense ejection. After controlling for ejaculate volume, we found socially subdominant males suffered higher ejection intensity. After controlling for male and ejaculate effects, we found ejection risk increased and intensity declined as females mated with successive males. Collectively, these results reveal that sperm ejection risk and intensity are at least partly actively caused by female behavior and generate independent selective pressures on male and ejaculate phenotypes.