Sperm competition enhances functional capacity ot mammalian spermatozoa
Sperm competition enhances functional capacity ot mammalian spermatozoa
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DOI：
10.1073/pnas.0605795103
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发表时间：
2006-10-10
影响因子：
11.1
通讯作者：
Roldan, Eduardo R. S.
中科院分区：
文献类型：
--
作者：
Gomendio, Montserrat;Martin-Coello, Juan;Roldan, Eduardo R. S.
当雌性异性交配时，竞争对手雄性的精子会在雌性生殖道内竞争，以使卵子受精。精子竞争是一种强大的选择性力量，它塑造了性行为、精子产生和精子形态。然而，人们对精子竞争对受精相关过程的影响知之甚少，因为人们一直认为精子竞争只涉及一场争夺受精地点的比赛。我们比较了四种密切相关的啮齿类动物，它们的精子竞争程度不同，以检查准备与卵子相互作用的精子比例(获得能力的)以及对自然刺激剂发生顶体反应的精子比例是否存在差异。我们的结果表明，不同物种之间精子竞争水平的差异与获得能力的精子比例和对孕酮(一种与卵子相关的信号)有反应的精子比例有关。因此，精子竞争有利于更多有能力受精的精子，以及对卵子发出的信号更敏感、可能更快穿透卵子的精子。这些结果表明，与之前的假设相反，来自竞争雄性的精子之间的竞争在受精地点继续进行。这些发现可能具有进一步的进化意义，因为受精过程中精子竞争力的增强可能会增加雌性多精症的风险。这可能导致两性之间的对抗性共同进化，并可能有助于解释观察到的受精相关性状的快速差异。
When females mate promiscuously, sperm from rival males compete within the female reproductive tract to fertilize ova. Sperm competition is a powerful selective force that has shaped sexual behavior, sperm production, and sperm morphology. However, nothing is known about the influence of sperm competition on fertilization-related processes, because it has been assumed that sperm competition only involves a race to reach the site of fertilization. We compared four closely related rodent species with different levels of sperm competition to examine whether there are differences in the proportion of spermatozoa that become ready to interact with the ovum ("capacitated") and in the proportion of spermatozoa that experience the acrosome reaction in response to a natural stimulant. Our results show that differences between species in levels of sperm competition were associated with the proportion of spermatozoa that undergo capacitation and with the proportion of spermatozoa that respond to progesterone, an ovum-associated signal. Sperm competition thus favors a larger population of spermatozoa that are competent to fertilize, and spermatozoa that are more sensitive to the signals emitted by the ovum and that may penetrate the ova vestments more rapidly. These results suggest that, contrary to previous assumptions, competition between spermatozoa from rival males continues at the site of fertilization. These findings may have further evolutionary implications because the enhanced competitiveness of spermatozoa during fertilization may increase the risk of polyspermy to females. This could lead to antagonistic coevolution between the sexes and may contribute to the explanation of the rapid divergence observed in fertilization-related traits.