Lüpold Stefan, Calhim Sara, Immler Simone, Birkhead Tim R
Department of Animal and Plant Sciences, University of Sheffield, Western Bank, Sheffield S10 2TN, UK.
Proc Biol Sci. 2009 Mar 22;276(1659):1175-81. doi: 10.1098/rspb.2008.1645.
Sperm velocity is one of the main determinants of the outcome of sperm competition. Since sperm vary considerably in their morphology between and within species, it seems likely that sperm morphology is associated with sperm velocity. Theory predicts that sperm velocity may be increased by enlarged midpiece (energetic component) or flagellum length (kinetic component), or by particular ratios between sperm components, such as between flagellum length and head size. However, such associations have rarely been found in empirical studies. In a comparative framework in passerine birds, we tested these theoretical predictions both across a wide range of species and within a single family, the New World blackbirds (Icteridae). In both study groups, sperm velocity was influenced by sperm morphology in the predicted direction. Consistent with theoretical models, these results show that selection on sperm morphology and velocity are likely to be concomitant evolutionary forces.
精子速度是精子竞争结果的主要决定因素之一。由于不同物种之间以及同一物种内部的精子形态差异很大，精子形态似乎很可能与精子速度相关。理论预测，精子中段（能量组成部分）增大或鞭毛长度（动力组成部分）增加，或者精子各组成部分之间的特定比例，如鞭毛长度与头部大小之间的比例，可能会提高精子速度。然而，这类关联在实证研究中很少被发现。在雀形目鸟类的一个比较框架中，我们在广泛的物种范围内以及在一个单一的科——新大陆黑鹂（拟鹂科）内检验了这些理论预测。在这两个研究组中，精子速度均按预测方向受到精子形态的影响。与理论模型一致，这些结果表明，对精子形态和速度的选择很可能是相伴的进化力量。
