Data from: Maternal effects are long lasting and influence female offspring’s reproductive strategy in the swordtail fish Xiphophorus multilineatus

The adaptive benefits of maternal investment into individual offspring (inherited environmental effects) will be shaped by selection on mothers as well as their offspring, often across variable environments. We examined how a mother’s nutritional environment interacted with her offspring’s nutritional and social environment in Xiphophorus multilineatus, a livebearing fish. Fry from mothers reared on two different nutritional diets (HQ = high quality, and LQ = low quality) were all reared on a LQ diet in addition to being split between two social treatments: exposed to a large adult male during development, and not exposed. Mothers raised on a HQ diet produce offspring that were not only initially larger (at 14 days of age), but grew faster, and were larger at sexual maturity, suggesting that the fry produced by mothers on LQ diets were at a disadvantage. Male offspring from mothers raised on both diets responded to the exposure to courter males by growing faster, however the response of their sisters varied with mother’s diet; Females from HQ mothers reduced growth if exposed to a courter male, while females from LQ mothers increased growth. Therefore, we detected variation in maternal investment depending on female size and diet, and the effects of this variation on offspring were long-lasting and sex specific. Our results support the maternal stress hypothesis, with selection on mothers to reduce investment in low quality environments that was not beneficial to the offspring. In addition, the interaction we detected between the mother’s nutritional environment and the female offspring’s social environment suggests that female offspring adopted different reproductive strategies depending on maternal investment.

母体对单个后代的投入（可遗传的环境效应）的适应性优势，会受到母体及其后代的选择压力塑造，且通常处于多变的环境之中。我们以多线剑尾鱼（Xiphophorus multilineatus）——一种胎生鱼类——为研究对象，探究了母体营养环境与后代营养及社会环境之间的交互作用。饲喂两种不同营养日粮（高品质日粮HQ、低品质日粮LQ）的母本所产幼鱼，均统一饲喂LQ日粮，并被分为两组社会处理组：发育过程中暴露于大型成年雄性个体，以及不暴露于该类个体。饲喂HQ日粮的母本所产后代，不仅在14日龄时初始体型更大，且生长速度更快，性成熟时体型也更大，这表明饲喂LQ日粮的母本所产幼鱼处于发育劣势。两种日粮组母本的雄性后代均会因暴露于求偶雄性而加快生长，但雌性后代的响应则随母本日粮不同而存在差异：来自HQ日粮母本的雌性个体若暴露于求偶雄性，其生长会受到抑制，而来自LQ日粮母本的雌性个体生长则会提升。因此，我们发现母体投入的差异取决于雌性个体的体型与日粮组成，且该差异对后代的影响具有长期性与性别特异性。我们的研究结果支持母体应激假说：在对后代无益的低品质环境中，母本会受到选择压力而减少对后代的投入。此外，我们检测到的母体营养环境与雌性后代社会环境之间的交互作用表明，雌性后代会依据母体投入的差异采取不同的繁殖策略。