Devigili Alessandro, Di Nisio Andrea, Grapputo Alessandro, Pilastro Andrea
Department of Biology, University of Padua, I-35131, Padova, Italy.
Evolution. 2016 Aug;70(8):1829-43. doi: 10.1111/evo.12989. Epub 2016 Jul 19.
Female sperm storage (FSS) is taxonomically widespread and often associated with intense sperm competition, yet its consequences on postcopulatory sexual selection (PCSS) are poorly known. Theory predicts that FSS will reduce the strength of PCSS, because sperm characteristics favored before and after FSS may be traded-off, and opportunities for nondirectional PCSS should increase. We explored these questions in the guppy (Poecilia reticulata), by allowing females to mate multiply and by comparing the paternity pattern in two successive broods. Contrary to predictions, the variance in male fertilization success increased after FSS, driven by a change in male paternity share across broods. This change was positively associated with sperm velocity (measured before FSS) but not with the duration of FSS, indirectly suggesting that faster sperm were better in entering female storage organs, rather than in persisting within them. Other male traits, such as male size and orange color, heterozygosity, and relatedness to the female, did not influence paternity after FSS. These results indicate that processes associated with FSS tend to reinforce the strength of PCSS in guppies, rather than weaken it. Further work is necessary to test whether this pattern changes in case of more prolonged FSS.
雌性精子储存（FSS）在分类学上广泛存在，且常常与激烈的精子竞争相关联，然而其对交配后性选择（PCSS）的影响却鲜为人知。理论预测，FSS会降低PCSS的强度，因为在FSS前后受到青睐的精子特征可能会相互权衡，而且非定向PCSS的机会应该会增加。我们通过让雌性孔雀鱼（孔雀鱼）多次交配，并比较两个连续繁殖批次中的父权模式，来探究这些问题。与预测相反，在FSS之后，雄性受精成功率的方差增加了，这是由各繁殖批次中雄性父权份额的变化所驱动的。这种变化与精子速度（在FSS之前测量）呈正相关，但与FSS的持续时间无关，这间接表明更快的精子在进入雌性储存器官方面表现更好，而不是在其中持续存在方面。其他雄性特征，如雄性大小和橙色、杂合性以及与雌性的亲缘关系，在FSS之后并未影响父权。这些结果表明，与FSS相关的过程往往会增强孔雀鱼中PCSS的强度，而不是削弱它。有必要进一步开展工作，以测试在FSS持续时间更长的情况下这种模式是否会发生变化。
