ABSTRACT: The escape of Atlantic salmon Salmo salar from aquaculture has been identified as a significant threat to the persistence and stability of wild salmon populations. Yet the magnitude of phenotypic impacts due to hybridization remains largely unresolved. We evaluated the phenotypic consequences of hybridization using geometric morphometrics both under natural conditions in the wild and in the laboratory using common garden experiments. Juvenile Atlantic salmon field-collected in 2015 and 2016 from 18 southern Newfoundland rivers were classified as pure wild, pure farm, or F₁ hybrids using genetic assignment. Overall size and shape differences between wild and farm, and wild and F₁ hybrid individuals were small, largely size related, and present between pure farm and other crosses. Laboratory-reared pure wild, pure farm, and F₁ hybrid salmon were grown in tank and semi-natural conditions. Wild fish were significantly larger than both farm and hybrid salmon at first feeding; these size differences remained at 80 d post first feeding under semi-natural conditions, but all crosses were the same size in tank conditions, and there were no differences between pure farm and hybrid individuals under either condition. Significant shape differences were present among all pairwise comparisons under tank conditions, and in semi-natural conditions, pure wild individuals differed significantly from pure farm and hybrid individuals. Our results suggest phenotypic differences observed under laboratory conditions between wild and farm×wild hybrid individuals may not be appreciable in the wild, and that significant genetic changes may occur in wild populations experiencing hybridization in the absence of obvious large phenotypic changes.

中文翻译：

---

野生和实验条件下农场和野生大西洋鲑鲑 Salmo salar 杂交的形态学后果

摘要：大西洋鲑鱼从水产养殖中逃逸已被确定为对野生鲑鱼种群持续性和稳定性的重大威胁。然而，杂交对表型影响的程度在很大程度上仍未得到解决。我们在野外的自然条件下和在实验室中使用常见的花园实验评估了杂交的表型后果。2015 年和 2016 年从纽芬兰南部 18 条河流中采集的幼年大西洋鲑鱼通过基因分配被归类为纯野生、纯农场或 F _{1杂交种。野生与农场、野生与 F 1}之间的总体大小和形状差异杂种个体很小，主要与大小相关，并且存在于纯农场和其他杂交之间。实验室饲养的纯野生、纯农场和 F ₁杂交鲑鱼在水箱和半自然条件下生长。野生鱼在第一次喂食时明显大于养殖鲑鱼和杂交鲑鱼；这些大小差异在半自然条件下第一次喂养后 80 天仍然存在，但在水箱条件下所有杂交体的大小相同，并且在任何一种条件下纯农场和杂交个体之间没有差异。在水族箱条件下，所有成对比较中都存在显着的形状差异，在半自然条件下，纯野生个体与纯农场个体和杂交个体存在显着差异。我们的结果表明在实验室条件下观察到的野生和农场×野生杂交个体之间的表型差异在野外可能不明显，