Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn, United Kingdom.
Institute of Evolutionary Ecology and Conservation Genomics, University of Ulm, Albert-Einstein-Allee 11, 89081, Ulm, Germany.
Sci Rep. 2019 Oct 25;9(1):15366. doi: 10.1038/s41598-019-51672-1.
Sperm viability is a major male fitness component, with higher sperm viability associated with enhanced sperm competitiveness. While many studies have focussed on sperm viability from the male fitness standpoint, its impact on female fitness is less clear. Here we used a panel of 32 isogenic Drosophila simulans lines to test for genetic variation in sperm viability (percentage of viable cells). We then tested whether sperm viability affected female fitness by mating females to males from low or high sperm viability genotypes. We found significant variation in sperm viability among genotypes, and consistent with this, sperm viability was highly repeatable within genotypes. Additionally, females mated to high sperm viability males laid more eggs in the first seven hours after mating, and produced more offspring in total. However, the early increase in oviposition did not result in more offspring in the 8 hours following mating, suggesting that mating with high sperm-viability genotypes leads to egg wastage for females shortly after copulation. Although mating with high sperm-viability males resulted in higher female fitness in the long term, high quality ejaculates would result in a short-term female fitness penalty, or at least lower realised fitness, potentially generating sexual conflict over optimal sperm viability.
精子活力是雄性生育力的一个主要组成部分，较高的精子活力与增强的精子竞争力相关。虽然许多研究从雄性生育力的角度关注精子活力，但它对雌性生育力的影响尚不清楚。在这里，我们使用了一组 32 条同基因的果蝇 simulans 品系来测试精子活力（存活细胞的百分比）的遗传变异。然后，我们通过将雌性与低精子活力或高精子活力基因型的雄性交配，来测试精子活力是否会影响雌性的生育力。我们发现基因型之间的精子活力存在显著差异，而且与这一发现一致的是，精子活力在基因型内具有高度的可重复性。此外，与高精子活力的雄性交配的雌性在交配后的前 7 小时内产卵更多，并产生了更多的后代。然而，产卵的早期增加并没有导致交配后 8 小时内的后代数量增加，这表明与高精子活力的基因型交配会导致雌性在交配后不久出现卵子浪费。尽管与高精子活力的雄性交配会导致雌性的长期生育力提高，但高质量的精液会导致雌性的短期生育力下降，或者至少是较低的实际生育力，这可能会导致对最佳精子活力的性冲突。
