Nicholls E H, Burke T, Birkhead T R
Department of Animal and Planet Sciences, University of Sheffield, Western Bank, Sheffield S10 2TN, UK.
Proc Biol Sci. 2001 Jun 22;268(1473):1265-70. doi: 10.1098/rspb.2001.1615.
Males of many species allocate sperm to ejaculates strategically in response to variation in the risk and intensity of sperm competition. The notable exception is passerine birds, in which evidence for strategic allocation is absent. Here we report the results of a study testing for strategic ejaculate allocation in a passerine bird, the sand martin (Riparia riparia). Natural ejaculates were collected from males copulating with a model female. Ejaculates transferred in the presence of a rival male contained significantly more sperm than ejaculates transferred in the absence of a rival male. There was no evidence that this difference was due to the confounding effects of the year of ejaculate collection, the identity of the model female, the colony, the stage of season or the period of the day in which ejaculates were collected. A more detailed examination of the ejaculate patterns of individual males, achieved by the DNA profiling of ejaculates, provided additional evidence for strategic allocation of sperm.
许多物种的雄性会根据精子竞争风险和强度的变化，策略性地将精子分配到射精中。一个显著的例外是雀形目鸟类，目前尚无证据表明它们存在策略性分配。在此，我们报告一项针对雀形目鸟类崖沙燕（Riparia riparia）进行的策略性射精分配测试研究结果。从与模型雌性交配的雄性身上收集自然射精样本。在有竞争雄性在场时转移的射精样本所含精子明显多于无竞争雄性在场时转移的射精样本。没有证据表明这种差异是由于射精样本采集年份、模型雌性身份、鸟群、季节阶段或射精样本采集的时间段等混杂因素造成的。通过对射精样本进行DNA分析，对个体雄性的射精模式进行更详细的检查，为精子的策略性分配提供了额外证据。
