Data from: Male investments in high quality sperm improve fertilization success, but may have negative impact on offspring fitness in whitefish

Many ejaculate traits show remarkable variation in relation to male social status. Males in disfavoured (subordinate) mating positions often invest heavily on sperm motility but may have less available resources on traits (e.g., secondary sexual ornaments) that improve the probability of gaining matings. Although higher investments in sperm motility can increase the relative fertilization success of subordinate males, it is unclear whether status-dependent differences in sperm traits could have any consequences for offspring fitness. We tested this possibility in whitefish (Coregonus lavaretus L.) by experimentally fertilizing the eggs of 24 females with the sperm of either highly-ornamented (large breeding tubercles, dominant) or less-ornamented (small tubercles, subordinate) males (split-clutch breeding design). In comparison to highly-ornamented individuals, less-ornamented males had higher sperm motility, which fertilized the eggs more efficiently, but produced embryos with impaired hatching success. Also offspring size and body condition were lower among less-ornamented males. Furthermore, sperm motility was positively associated with the fertilization success and offspring size, but only in highly-ornamented males. Together our results indicate that male investments on highly motile (fertile) sperm is not necessarily advantageous during later offspring ontogeny and that male status-dependent differences in sperm phenotype may have important effects on offspring fitness in different life-history stages.诸多精液性状会随雄性社会地位呈现显著差异。处于交配劣势地位（从属雄性）的个体，往往会在精子活力上投入大量资源，但在提升交配机会的性状（如第二性征饰器）上可支配的资源却相对匮乏。尽管提升精子活力的投入能够提高从属雄性的相对受精成功率，但目前仍不清楚雄性精子性状随社会地位产生的差异，是否会对后代适合度造成任何影响。我们以白鲑（Coregonus lavaretus L.）为研究对象，采用分卵块繁殖设计（split-clutch breeding design），将24条雌鱼的鱼卵分别用携带明显第二性征（大型繁殖结节，优势雄性）或不明显第二性征（小型繁殖结节，从属雄性）的雄性的精子进行人工受精。相较于携带明显第二性征的雄性个体，从属雄性的精子活力更高，受精效率也更强，但由此产生的胚胎孵化成功率却更低。此外，从属雄性所产后代的体型与体况均更差。进一步分析显示，精子活力与受精成功率及后代体型呈正相关，但这一关联仅在优势雄性群体中成立。综合来看，本研究结果表明，雄性对高活力（高受精能力）精子的投入，在后代后续个体发育阶段未必具备进化优势；且雄性精子表型随社会地位产生的差异，可能在不同生活史阶段对后代适合度产生重要影响。