Female promiscuity promotes the evolution of faster sperm in cichlid fishes
Female promiscuity promotes the evolution of faster sperm in cichlid fishes
复制标题
DOI：
10.1073/pnas.0809990106
复制
发表时间：
2009-01-27
影响因子：
11.1
通讯作者：
Balshine, Sigal
中科院分区：
文献类型：
--
作者：
Fitzpatrick, John L.;Montgomerie, Robert;Balshine, Sigal
精子竞争，即竞争性雄性射精之间为使雌性卵子受精而进行的竞争，是影响射精性状的一种常见而强大的进化力量。在射精之间的竞争性相互作用中，预计更长和更快的精子将具有优势。然而，迄今为止，对精子竞争理论这一关键预测的支持不一。在这里，我们利用坦噶尼喀湖慈鲷的壮观辐射来检查 29 个密切相关物种的精子特征。我们提供了系统发生学上强有力的证据，证明精子竞争程度较高的物种拥有游动速度更快的精子。我们还表明，精子竞争选择了男性射精中精子数量、大小和寿命的增加，并且与理论预期相反，我们在种间分析中没有发现精子性状之间权衡的证据。此外，精子游动速度与物种内的精子长度呈正相关，但与物种内的精子长度无关。这些在种内和种间水平上对精子竞争的不同反应为先前研究的模棱两可的结果提供了简单而有力的解释。通过系统发育分析，我们还重建了该分类群中性状进化的可能进化路线，并表明，为了应对精子竞争程度的增加，该分支中精子性状的进化始于更快（因此更具竞争力）精子的进化。
Sperm competition, the contest among ejaculates from rival males to fertilize ova of a female, is a common and powerful evolutionary force influencing ejaculate traits. During competitive interactions between ejaculates, longer and faster spermatozoa are expected to have an edge; however, to date, there has been mixed support for this key prediction from sperm competition theory. Here, we use the spectacular radiation of cichlid fishes from Lake Tanganyika to examine sperm characteristics in 29 closely related species. We provide phylogenetically robust evidence that species experiencing greater levels of sperm competition have faster-swimming sperm. We also show that sperm competition selects for increases in the number, size, and longevity of spermatozoa in the ejaculate of a male, and, contrary to expectations from theory, we find no evidence of trade-offs among sperm traits in an interspecific analysis. Also, sperm swimming speed is positively correlated with sperm length among, but not within, species. These different responses to sperm competition at intra-and interspecific levels provide a simple, powerful explanation for equivocal results from previous studies. Using phylogenetic analyses, we also reconstructed the probable evolutionary route of trait evolution in this taxon, and show that, in response to increases in the magnitude of sperm competition, the evolution of sperm traits in this clade began with the evolution of faster (thus, more competitive) sperm.