Data from: Maternal allocation of carotenoids increases tolerance to bacterial infection in brown trout

Life-history theory predicts that iteroparous females allocate their resources differently among different breeding seasons depending on their residual reproductive value. In iteroparous salmonids there is typically much variation in egg size, egg number, and in the compounds that females allocate to their clutch. These compounds include various carotenoids whose functions are not sufficiently understood yet. We sampled 37 female and 35 male brown trout from natural streams, collected their gametes for in vitro fertilizations, experimentally produced 185 families in 7 full-factorial breeding blocks, raised the developing embryos singly (n = 2960), and either sham-treated or infected them with Pseudomonas fluorescens. We used female redness (as a measure of carotenoids stored in the skin) and their allocation of carotenoids to clutches to infer maternal strategies. Astaxanthin contents largely determined egg colour. Neither egg weight nor female size was correlated with the content of this carotenoid. However, astaxanthin content was positively correlated with larval growth and with tolerance against P. fluorescens. There was a negative correlation between female skin redness and the carotenoid content of their eggs. Although higher astaxanthin contents in the eggs were associated with an improvement of early fitness-related traits, some females appeared not to maximally support their current offspring as revealed by the negative correlation between female red skin colouration and egg carotenoid content. This correlation was not explained by female size and supports the prediction of a maternal trade-off between current and future reproduction.

生活史理论（life-history theory）预测，多次繁殖雌性会依据自身剩余繁殖价值（residual reproductive value），在不同繁殖季间差异化分配资源。对于鲑科（salmonids）鱼类而言，雌鱼的卵粒大小、产卵量以及向卵块中投入的各类物质均存在显著变异，其中包含多种功能尚未被充分阐明的类胡萝卜素（carotenoids）。本研究从天然溪流中采集了37条雌性与35条雄性褐鳟，收集其生殖细胞用于体外受精（in vitro fertilizations），通过7个全因子繁殖组（full-factorial breeding blocks）人工构建185个家系，将2960枚发育中的胚胎单独饲养，并分为假处理组与感染荧光假单胞菌（Pseudomonas fluorescens）组。本研究以雌性皮肤红度作为皮肤储存类胡萝卜素的量化指标，结合雌鱼向卵块中分配的类胡萝卜素水平推断其母本繁殖策略，结果显示虾青素（astaxanthin）含量是决定卵粒颜色的核心因素；卵粒重量与雌鱼体型均与该类胡萝卜素含量无显著相关性，但虾青素含量与幼体生长速率、抗荧光假单胞菌感染能力呈正相关，此外雌性皮肤红度与其卵粒的类胡萝卜素含量呈负相关。尽管卵粒中更高的虾青素含量与早期适合度相关性状（fitness-related traits）的提升存在关联，但部分雌鱼并未最大化投入资源以支持当前后代，这一现象可通过雌性皮肤红度与卵粒类胡萝卜素含量的负相关关系得到验证，且该相关性不受雌鱼体型的影响，印证了母本在当前繁殖与未来繁殖间存在权衡的理论预测。