Arnqvist Göran, Danielsson Ingela
Department of Animal Ecology, University of Umeå, SE-901 87 Umeå, Sweden.
Animal Ecology, Department of Zoology, Göteborg University, Box 463, SE-405 30 Göteborg, Sweden.
Evolution. 1999 Feb;53(1):147-156. doi: 10.1111/j.1558-5646.1999.tb05340.x.
Recent theoretical and empirical interest in postmating processes have generated a need for increasing our understanding of the sources of variance in fertilization success among males. Of particular importance is whether such postmating sexual selection merely reinforces the effects of premating sexual selection or whether other types of male traits are involved. In the current study, we document large intraspecific variation in last male sperm precedence in the water strider Gerris lateralis. Male relative paternity success was repeatable across replicate females, showing that males differ consistently in their ability to achieve fertilizations. By analyzing shape variation in male genital morphology, we were able to demonstrate that the shape of male intromittent genitalia was related to relative paternity success. This is the first direct experimental support for the suggestion that male genitalia evolve by postmating sexual selection. A detailed analysis revealed that different components of male genitalia had different effects, some affecting male ability to achieve sperm precedence and others affecting male ability to avoid sperm precedence by subsequent males. Further, the effects of the shape of the male genitalia on paternity success was in part dependent on female morphology, suggesting that selection on male genitalia will depend on the frequency distribution of female phenotypes. We failed to find any effects of other morphological traits, such as male body size or the degree of asymmetry in leg length, on fertilization success. Although males differed consistently in their copulatory behavior, copulation duration was the only behavioral trait that had any significant effect on paternity.
近期对交配后过程的理论和实证研究兴趣引发了一种需求，即需要增进我们对雄性间受精成功率差异来源的理解。特别重要的是，这种交配后性选择仅仅是强化了交配前性选择的效果，还是涉及其他类型的雄性特征。在当前研究中，我们记录了宽肩水黾（Gerris lateralis）中最后交配雄性精子优先性存在的种内巨大差异。雄性的相对父权成功率在不同的重复雌性中具有重复性，这表明雄性在实现受精的能力上存在持续差异。通过分析雄性生殖器形态的形状变异，我们能够证明雄性插入式生殖器的形状与相对父权成功率相关。这是对雄性生殖器通过交配后性选择进化这一观点的首个直接实验支持。详细分析表明，雄性生殖器的不同组成部分具有不同影响，一些影响雄性获得精子优先性的能力，另一些影响雄性避免被后续雄性获得精子优先性的能力。此外，雄性生殖器形状对父权成功率的影响部分取决于雌性形态，这表明对雄性生殖器的选择将取决于雌性表型的频率分布。我们未发现其他形态特征，如雄性体型或腿长不对称程度，对受精成功率有任何影响。尽管雄性在交配行为上存在持续差异，但交配持续时间是唯一对父权有显著影响的行为特征。
