Data from: Quantifying heritable variation in fitness-related traits of wild, farmed and hybrid Atlantic salmon families in a wild river environment

Farmed fish are typically genetically different from wild conspecifics. Escapees from fish farms may contribute one-way gene flow from farm to wild gene pools, which can depress population productivity, dilute local adaptations and disrupt coadapted gene complexes. Here, we reanalyse data from two experiments (McGinnity et al., 1997, 2003) where performance of Atlantic salmon (Salmo salar) progeny originating from experimental crosses between farm and wild parents (in three different cohorts) were measured in a natural stream under common garden conditions. Previous published analyses focussed on group-level differences but did not account for pedigree structure, as we do here using modern mixed-effect models. Offspring with one or two farm parents exhibited poorer survival in their first and second year of life compared with those with two wild parents and these group-level inferences were robust to excluding outlier families. Variation in performance among farm, hybrid and wild families was generally similar in magnitude. Farm offspring were generally larger at all life stages examined than wild offspring, but the differences were moderate (5–20%) and similar in magnitude in the wild versus hatchery environments. Quantitative genetic analyses conducted using a Bayesian framework revealed moderate heritability in juvenile fork length and mass and positive genetic correlations (>0.85) between these morphological traits. Our study confirms (using more rigorous statistical techniques) previous studies showing that offspring of wild fish invariably have higher fitness and contributes fresh insights into family-level variation in performance of farm, wild and hybrid Atlantic salmon families in the wild. It also adds to a small, but growing, number of studies that estimate key evolutionary parameters in wild salmonid populations. Such information is vital in modelling the impacts of introgression by escaped farm salmon.

养殖鱼类通常与野生同类存在遗传差异。养殖场逃逸个体可能会造成从养殖种群到野生种群的单向基因流，该过程会降低种群生产力、稀释本地适应性，并破坏共适应基因复合体。本研究重新分析了两项实验（McGinnity等人，1997、2003）的数据：该实验以养殖场亲本与野生亲本进行杂交得到的大西洋鲑（Salmo salar）后代（共3个不同同期组），在同质园条件下的自然溪流中开展了性能测定。此前已发表的相关分析仅关注组间差异，并未像本研究这般借助现代混合效应模型考量系谱结构。携带1个或2个养殖亲本的后代，在生命的第1、2年的存活率均低于携带2个野生亲本的后代；且排除异常家系后，上述组间差异的统计推断结果依然稳健。养殖组、杂交组与野生组家系间的性能差异幅度整体相近。各检测生活史阶段中，养殖组后代的体型均普遍大于野生组，但差异幅度中等（5%~20%），且在自然溪流与孵化场环境中的差异幅度相似。采用贝叶斯框架开展的定量遗传分析显示，幼鱼叉长与体质量具有中等程度的遗传力，且这两个形态性状间存在强正遗传相关（>0.85）。本研究采用更为严谨的统计方法，验证了此前关于野生鱼类后代适合度普遍更高的研究结论，并为养殖场、野生组及杂交组大西洋鲑家系在自然环境中的性能差异提供了全新的家系层面研究视角。本研究同时补充了少量但数量正逐步增长的、针对野生鲑科种群关键进化参数的估算研究。这类信息对于模拟逃逸养殖鲑的基因渐渗所带来的生态影响至关重要。