Selection for longer-lived sperm within ejaculate reduces reproductive ageing in offspring

Males produce numerous sperm in a single ejaculate that greatly outnumber their potential egg targets. Recent studies found that phenotypic and genotypic variation among sperm in a single ejaculate of a male affects the fitness and performance of the resulting offspring. Specifically, within-ejaculate sperm selection for sperm longevity increased the performance of the resulting offspring in several key life-history traits in early-life. Because increased early-life reproductive performance often correlates with rapid ageing, it is possible that within-ejaculate sperm selection increases early-life fitness at the cost of accelerated senescence. Alternatively, within-ejaculate sperm selection could improve offspring quality throughout the life cycle, including reduced age-specific deterioration. We tested the two alternative hypotheses in an experimental setup using zebrafish Danio rerio. We found that within-ejaculate sperm selection for sperm longevity reduced age-specific deterioratio...雄性单次射精产生的精子数量远多于其潜在的卵子靶标。近期研究发现，雄性单次射精内的精子群体所存在的表型与基因型差异，会影响子代的适合度与表现。具体而言，基于精子寿命的射精内精子选择，可提升子代在早期阶段多个关键生活史性状中的表现。由于早期生殖性能提升往往与快速衰老相关，因此射精内精子选择有可能以加速衰老为代价，提升子代的早期适合度。另一种可能性则是，射精内精子选择可在整个生命周期中改善子代质量，包括降低年龄特异性的生理衰退。我们利用斑马鱼（Danio rerio）搭建实验体系，对这两种对立假说进行了验证。研究发现，基于精子寿命的射精内精子选择可降低年龄特异性衰退……