PDF(Pubmed)
Abstract：
Endangered wild fish populations are commonly supported by hatchery propagation. However, hatchery-reared fish experience very different selective pressures compared to their wild counterparts, potentially causing genotype-by-environment interactions (G × E) in essential fitness traits. We experimentally studied early selection in a critically endangered landlocked Atlantic salmon population, first from fertilization to the swim-up stage in a common hatchery setting, and thereafter until the age of 5 months in two contrasting rearing environments. Swim-up progeny were moved either to standard indoor hatchery tanks involving conventional husbandry or to seminatural outdoor channels providing only natural food. After the first summer, sampled survivors were assigned to their families by genotyping. Early survival until the swim-up stage was mostly determined by maternal effects, but also involved significant variation due to sires and full-sib families (potential genetic effects). High on-growing survival in hatchery tanks (88.7%) maintained a more even distribution among families (relative share 1.5%-4.2%) than the seminatural environment (0.0%-5.4%). This heterogeneity was mostly maternal, whereas no independent paternal effect occurred. Heritability estimates were high for body size traits in both environments (0.62-0.69). Genetic correlations between the environments were significantly positive for body size traits (0.67-0.69), and high body condition in hatchery was also genetically linked to rapid growth in the seminatural environment (0.54). Additive and phenotypic growth variation increased in the seminatural environment, but scaling effects probably played a less significant role for G × E, compared to re-ranking of genotypes. Our results suggest that not only maternal effects, but also genetic effects, direct selection according to the environmental conditions experienced. Consistently high genetic variation in growth implies that, despite its low overall genetic diversity and long history in captive rearing (>50 years), this landlocked Atlantic salmon population still possesses adaptive potential for response to change from hatchery rearing back to more natural conditions.
摘要：
濒危野生鱼类种群通常由孵化场繁殖支持。然而,与野生鱼类相比，孵化场饲养的鱼类经历了非常不同的选择压力，在基本适应度性状中可能导致基因型与环境的相互作用(G×E)。我们通过实验研究了极度濒危的内陆大西洋鲑鱼种群的早期选择，首先从受精到普通孵化场的游泳阶段，此后，在两个截然不同的饲养环境中直至5个月大。游泳后代被转移到涉及常规畜牧业的标准室内孵化场，或仅提供天然食物的半自然室外通道。第一个夏天之后,样本幸存者通过基因分型被分配到他们的家庭。直到游泳上升阶段的早期生存主要取决于母体的影响，但也涉及由于父亲和全同胞家庭的显着变异（潜在的遗传效应）。与半自然环境（0.0％-5.4％）相比，孵化场水箱中的高存活率（88.7％）在家庭中的分布更加均匀（相对份额为1.5％-4.2％）。这种异质性主要是母体的，而没有发生独立的父系效应。在两种环境中，体型性状的遗传力估计值都很高（0.62-0.69）。环境之间的遗传相关性对于体型性状（0.67-0.69），孵化场的高身体状况在遗传上也与半自然环境中的快速生长有关（0.54）。半自然环境中的加性和表型生长变异增加，但是缩放效应对G×E的作用可能不那么重要，与基因型的重新排名相比。我们的结果表明，不仅是产妇的影响，还有遗传效应，根据所经历的环境条件直接选择。生长中的持续高遗传变异意味着，尽管其总体遗传多样性低，圈养历史悠久(>50年)，这种内陆的大西洋鲑鱼种群仍然具有适应潜力，可以应对从孵化场饲养到更自然的条件的变化。
