摘要
In most species, females mate multiply within a reproductive cycle, invoking post-copulatory selection on ejaculatory components. Much research has focused on disentangling the key traits important in deciding the outcomes of sperm competition and investigating patterns of covariance among these traits. Less attention has focused on the degree to which such patterns might be context-dependent. Here, we examine whether the expression of sperm viability—a widely used measure of sperm quality—and patterns of covariance between this trait and male reproductive morphologies, change across distinct age classes and across naturally occurring genotypes, when expressed in both heterozygotic (extreme outbred) and homozygotic (extreme inbred) states in the fruitfly Drosophila melanogaster. Older males, and heterozygous males, generally exhibited higher sperm viability. The male age effect seems at least partly explained by a positive association between sperm numbers and viability. First, old males possessed more stored sperm than young males, and second, sperm numbers and viability were also positively associated within each age class. Furthermore, we found a positive association between sperm viability and testis size, but only among heterozygous, old males. These results suggest that sperm quality is a labile trait, with expression levels that are context-dependent and shaped by multiple, potentially interacting, factors.
摘要译文
在大多数物种中，女性在繁殖周期中相互交配，引发了对射精成分的后交配选择。许多研究集中在解决决定精子竞争结果和调查这些特征之间协方差模式重要的关键特征。较少的注意力集中在这种模式可能与上下文相关的程度。这里，我们检查精子活力的表达 - 广泛使用的精子质量测量和这种性状与男性生殖形态之间的协方差模式，改变不同年龄层次和跨天然存在的基因型，当在果蝇果蝇中以杂合（极端近交）和纯合（极近交系）状态表达时。老年男性和杂合子雄性，一般表现出较高的精子活力。男性年龄影响似乎至少部分由精子数量与生存能力之间的正相关关系解释。第一，老年男性存储的精子比年轻男性更多;其次，精子数量和生存能力也在每个年龄段内都有正相关。此外，我们发现精子活力和睾丸大小之间存在正相关，但仅在杂合性，老年男性之间。这些结果表明，精子质量是不稳定的特征，具有上下文相关性并由多个潜在交互作用因素塑造的表达水平。
Daniel Paz Decanini[1];Bob B. M. Wong[1];Damian K. Dowling[1]. Context-dependent expression of sperm quality in the fruitfly[J]. Biology Letters, 2013,9(6)