What use is an infertile sperm?: A comparative study of sperm-heteromorphic Drosophila
What use is an infertile sperm?: A comparative study of sperm-heteromorphic Drosophila
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DOI：
10.1111/j.1558-5646.2007.00280.x
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发表时间：
2008-02-01
期刊：
影响因子：
3.3
通讯作者：
Snook, Rhonda R.
中科院分区：
文献类型：
--
作者：
Holman, Luke;Freckleton, Robert P.;Snook, Rhonda R.
精子的大小和数量是决定男性生殖成功与否的重要因素。果蝇具有显著的精子产生策略多样性，包括单个雄性产生多种精子形态，这种现象被称为精子异型性。精子-异型的果蝇种类在暗箱组产生大量不育的“准精子”，除了可育的真精子。傍胚层被假设在受精过程中扮演着许多角色，主要集中在它们在交配后性选择中的潜在功能。然而，parasperm的进化意义仍然未知。在此，我们测量了13个暗箱目物种中雄性和雌性的形态、行为和生活史特征，用比较的方法来检验关于副精子功能的竞争性假设。我们发现，副精子的大小与雌性生殖道形态无关，但与精子竞争的两个指标呈负相关，这表明交配后的性选择可能确实影响了副精子的进化。我们还发现了大量的男性和女性生殖特征之间的共同进化。其中一些关系在精子单型和精子异型分类群中都有发现，但其他的则不同。我们讨论了我们的结果对生殖性状的进化和副精子果蝇难以捉摸的功能的意义。
Sperm size and number are important determinants of male reproductive success. The genus Drosophila exhibits a remarkable diversity of sperm production strategies, including the production of multiple sperm morphs by individual males, a phenomenon called sperm heteromorphism. Sperm-heteromorphic Drosophila species in the obscura group produce large numbers of infertile "parasperm" in addition to fertile eusperm. Parasperm have been hypothesized to perform a number of roles in place of fertilization, predominantly focused on their potential function in postcopulatory sexual selection. However, the evolutionary significance of parasperm remains unknown. Here we measured several male and female morphological, behavioral, and life-history traits in 13 obscura group species to test competing hypotheses of parasperm function using comparative methods. We found that parasperm size was unrelated to female reproductive tract morphology but was negatively related to our two indices of sperm competition, suggesting that postcopulatory sexual selection may indeed have shaped the evolution of parasperm. We also found abundant coevolution between male and female reproductive traits. Some of these relationships have been found in both sperm-monomorphic and sperm-heteromorphic taxa, but others are dissimilar. We discuss the significance of our results to the evolution of reproductive traits and the elusive function of Drosophila parasperm.