Reinhardt Klaus
Department of Animal and Plant Sciences, University of Sheffield, Western Bank, UK.
Q Rev Biol. 2007 Dec;82(4):375-93. doi: 10.1086/522811.
Animal breeding research, reproductive biology, and cellular biogerontology show that fertilization rates and zygote viability critically depend on sperm age. Sexual selection research focuses on differences between male genotypes in sperm performance, such as motility, competitive ability, or compatibility with eggs, but without considering sperm age. A combined view (that the thermodynamically inevitable decline in sperm performance selects for traits in diploid individuals to prevent fertilization with aged sperm) has received very little attention. In this paper, I correct this bias and show that many male and female traits affect sperm aging or the sperm age distribution at any reproductive event. Such traits coincide well with condition-dependent traits considered sexually selected: multiple mating by both sexes, high sperm production rates, the delivery of dense ejaculates containing many sperm (including nonfertilizing types), the packaging of sperm into spermatophores, male and female sperm ejection, sexual coercion, as well as the production of showy antioxidants and various cellular and nuclear repair mechanisms. I conclude that altering the sperm age distribution at any step during reproduction can be an origin of sexually selected traits, and may explain presently observed paternity variation without assuming genetic incompatibility of gametes.
动物育种研究、生殖生物学和细胞生物老年学表明，受精率和受精卵活力严重依赖于精子的年龄。性选择研究聚焦于雄性基因型在精子性能方面的差异，如活力、竞争能力或与卵子的兼容性，但未考虑精子年龄。一种综合观点（即精子性能在热力学上不可避免的衰退促使二倍体个体形成某些性状，以防止与老化精子受精）很少受到关注。在本文中，我纠正了这一偏差，并表明许多雄性和雌性性状会影响精子老化或任何生殖事件中的精子年龄分布。这些性状与被视为性选择的条件依赖性性状高度吻合：两性的多次交配、高精子产生率、输送含有大量精子（包括非受精类型）的浓稠精液、将精子包装成精荚、雄性和雌性的精子排出、性胁迫，以及产生艳丽的抗氧化剂和各种细胞及核修复机制。我得出结论，在生殖过程的任何阶段改变精子年龄分布都可能是性选择性状的起源，并且可能无需假设配子的遗传不兼容性就能解释目前观察到的父权差异。
