Evans Jonathan P, Sherman Craig D H
Centre for Evolutionary Biology, School of Animal Biology, University of Western Australia, Crawley, Australia.
Biol Bull. 2013 Aug;224(3):166-83. doi: 10.1086/BBLv224n3p166.
Many marine invertebrate taxa are broadcast spawners, where multiple individuals release their gametes into the water for external fertilization, often in the presence of gametes from heterospecifics. Consequently, sperm encounter the considerable challenges of locating and fertilizing eggs from conspecific females. To overcome these challenges, many taxa exhibit species-specific attraction of sperm toward eggs through chemical signals released from eggs (sperm chemotaxis) and species-specific gamete recognition proteins (GRPs) that mediate compatibility of gametes at fertilization. In this prospective review, we highlight these selective forces, but also emphasize the role that sexual selection, manifested through sperm competition, cryptic female choice, and evolutionary conflicts of interest between the sexes (sexual conflict), can also play in mediating the action of egg chemoattractants and GRPs, and thus individual reproductive fitness. Furthermore, we explore patterns of selection at the level of gametes (sperm phenotype, gamete plasticity, and egg traits) to identify putative traits targeted by sexual selection in these species. We conclude by emphasizing the excellent, but relatively untapped, potential of broadcast-spawning marine invertebrates as model systems to illuminate several areas of research in post-mating sexual selection.
许多海洋无脊椎动物类群是体外受精生物，多个个体将配子释放到水中进行体外受精，通常是在存在异种配子的情况下。因此，精子在寻找同种雌性的卵子并使其受精方面面临巨大挑战。为了克服这些挑战，许多类群通过卵子释放的化学信号（精子趋化性）以及在受精时介导配子兼容性的物种特异性配子识别蛋白（GRP），表现出精子对卵子的物种特异性吸引。在这篇前瞻性综述中，我们强调了这些选择力，但也强调了性选择所起的作用，性选择通过精子竞争、雌性隐秘选择以及两性之间的利益进化冲突（性冲突）表现出来，它也可以在介导卵子化学引诱剂和GRP的作用，进而影响个体繁殖适应性方面发挥作用。此外，我们探讨了配子水平上的选择模式（精子表型、配子可塑性和卵子特征），以确定这些物种中性选择所针对的假定特征。我们最后强调，体外受精的海洋无脊椎动物作为模型系统，在阐明交配后性选择的几个研究领域方面具有巨大但尚未充分利用的潜力。
