ABSTRACT: Selection due to multi-generational domestication and genetically distinct origins raises concerns about potential fitness consequences of hybridization between farmed and wild Atlantic salmon. In Newfoundland (NF), Canada, the aquaculture industry uses the North American (NA) Saint John River strain, though site-specific permission has been granted to farm a European origin (EO) strain. We used complementary experiments to investigate differences in (1) dominance status and (2) growth and survival in allopatry (NF wild fish) versus sympatry (NF wild fish with NA/EO farmed individuals and related F₁ hybrids) in contrasting tank and semi-natural stream environments. NA farmed salmon were more dominant than NF wild individuals, with hybrids being intermediate in expression and not differing from wild fish. EO farmed salmon also tended to dominate NF wild individuals, but not significantly. Competition with farmed fish and hybrids did not affect the growth of wild fish in sympatry versus allopatry in the tank environment. However, that was not the case in one instance in the stream environment where wild fish in sympatry with NA farmed fish and hybrids outgrew those in allopatry. Within sympatric treatments, both EO and NA farmed salmon outgrew wild individuals in the tank environment, but not always in the stream environment (exception: NA farmed). Hybrids tended to display intermediate growth performance relative to farmed and wild fish in both environments. Survival did not differ among cross types in either environment. These findings suggest that irrespective of distinct origins, both EO and NA farmed salmon displayed greater dominance and growth than NF wild salmon in the tank environment. However, in the stream environment, competition imposed by NA farmed fish and related hybrids on wild fish appeared less than that imposed by the EO strain and related hybrids, as evident in growth performance. Findings thus provide valuable insight into the effects of hybridization and, consequently, fitness-related trait differences among divergent EO and NA farmed, NF wild, and F₁ hybrid populations of importance for the conservation and management of Atlantic salmon.

中文翻译：

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野生纽芬兰与养殖的欧洲和北美大西洋鲑鱼杂交的适应性结果

摘要：由于多代驯化和遗传上不同的起源而产生的选择引起了人们对养殖和野生大西洋鲑鱼杂交的潜在适应性后果的担忧。在加拿大纽芬兰 (NF)，水产养殖业使用北美 (NA) 圣约翰河品系，但已获得养殖欧洲来源 (EO) 品系的特定地点许可。我们使用互补实验来研究异域分布（NF 野生鱼）与同域分布（具有 NA/EO 养殖个体的 NF 野生鱼和相关 F _{1 ）的优势地位和（2）生长和存活的差异}混合动力车）在对比坦克和半自然流环境中。NA 养殖鲑鱼比 NF 野生个体更具优势，杂交种在表达上处于中间状态，与野生鱼类没有区别。EO 养殖的鲑鱼也倾向于支配 NF 野生个体，但并不显着。与养殖鱼类和杂交种的竞争并不影响野生鱼类在水箱环境中同域与异域的生长。然而，在溪流环境中的一个例子中情况并非如此，在这种情况下，与 NA 养殖鱼类和杂交种共存的野生鱼类比异地养殖的鱼类长得多。在同域处理中，EO 和 NA 养殖的鲑鱼在水槽环境中的生长速度都超过野生个体，但在溪流环境中并不总是如此（例外：NA 养殖）。在这两种环境中，杂交种往往表现出相对于养殖和野生鱼类的中等生长性能。在任何一种环境中，杂交类型的生存率都没有差异。这些发现表明，无论起源如何，EO 和 NA 养殖三文鱼在水槽环境中都比 NF 野生三文鱼表现出更强的优势和生长。然而，在溪流环境中，NA 养殖鱼类和相关杂交种对野生鱼类施加的竞争似乎少于 EO 品系和相关杂交种施加的竞争，这在生长性能上很明显。因此，研究结果为杂交的影响提供了有价值的见解，并因此提供了不同的 EO 和 NA 养殖、NF 野生和 F 之间与适应性相关的性状差异 这些发现表明，无论起源如何，EO 和 NA 养殖三文鱼在水槽环境中都比 NF 野生三文鱼表现出更强的优势和生长。然而，在溪流环境中，NA 养殖鱼类和相关杂交种对野生鱼类施加的竞争似乎少于 EO 品系和相关杂交种施加的竞争，这在生长性能上很明显。因此，研究结果为杂交的影响提供了有价值的见解，并因此提供了不同的 EO 和 NA 养殖、NF 野生和 F 之间与适应性相关的性状差异 这些发现表明，无论起源如何，EO 和 NA 养殖三文鱼在水槽环境中都比 NF 野生三文鱼表现出更强的优势和生长。然而，在溪流环境中，NA 养殖鱼类和相关杂交种对野生鱼类施加的竞争似乎少于 EO 品系和相关杂交种施加的竞争，这在生长性能上很明显。因此，研究结果为杂交的影响提供了有价值的见解，并因此提供了不同的 EO 和 NA 养殖、NF 野生和 F 之间与适应性相关的性状差异 NA 养殖鱼类和相关杂交种对野生鱼类施加的竞争似乎小于 EO 菌株和相关杂交种施加的竞争，这在生长性能上很明显。因此，研究结果为杂交的影响提供了有价值的见解，并因此提供了不同的 EO 和 NA 养殖、NF 野生和 F 之间与适应性相关的性状差异 NA 养殖鱼类和相关杂交种对野生鱼类施加的竞争似乎小于 EO 菌株和相关杂交种施加的竞争，这在生长性能上很明显。因此，研究结果为杂交的影响提供了有价值的见解，并因此提供了不同的 EO 和 NA 养殖、NF 野生和 F 之间与适应性相关的性状差异₁对大西洋鲑鱼的保护和管理具有重要意义的杂交种群。