Unexpectedly simple Chinook salmon are known to return to spawn at two distinct times of the year: spring and fall. Individuals that return during these times have generally been referred to as parts of distinct groups, or ecotypes, with traits specific to their timing and presumed divergence being caused by the lack of interbreeding. By looking at genomes across fish from both runs, Thompson et al. found that a single genomic region of interest was nearly perfectly associated with run timing but not with other traits such as maturity and fat reserves (see the Perspective by McKinney). Further, they conclude that the region operates as a Mendelian trait, with assortment dictating run timing and associated phenotypes being caused by the migration environment rather than genetics. Science, this issue p. 609; see also p. 526 A single genomic region is associated with run timing in Chinook salmon. Differentiation between ecotypes is usually presumed to be complex and polygenic. Seasonal patterns of life history in salmon are used to categorize them into ecotypes, which are often considered “distinct” animals. Using whole-genome sequencing and tribal fishery sampling of Chinook salmon, we show that a single, small genomic region is nearly perfectly associated with spawning migration timing but not with adiposity or sexual maturity, traits long perceived as central to salmon ecotypes. Distinct migration timing does not prevent interbreeding between ecotypes, which are the result of a simple, ancient polymorphism segregating within a diverse population. Our finding that a complex migratory phenotype results from a single gene region will facilitate conservation and restoration of this iconic fish.

中文翻译：

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由迁移时间的简单变化控制的鲑鱼的复杂表型

众所周知，简单的奇努克鲑鱼会在一年中的两个不同时间重新产卵：春季和秋季。在这些时期返回的个体通常被称为不同群体或生态型的一部分，具有特定于其时间的特征和由于缺乏杂交而导致的假定分歧。通过查看两次运行中鱼的基因组，Thompson 等人。发现单个感兴趣的基因组区域与运行时间几乎完全相关，但与其他特征如成熟度和脂肪储备无关（参见 McKinney 的观点）。此外，他们得出结论，该区域作为孟德尔特征运行，分类决定运行时间和相关表型是由迁移环境而不是遗传引起的。科学，这个问题 p。609; 另见第。526 单个基因组区域与奇努克鲑鱼的运行时间相关。生态型之间的差异通常被认为是复杂的和多基因的。鲑鱼生活史的季节性模式被用来将它们归类为生态型，这些生态型通常被认为是“独特的”动物。使用奇努克鲑鱼的全基因组测序和部落渔业采样，我们表明单个小基因组区域与产卵迁移时间几乎完全相关，但与肥胖或性成熟无关，这些特征长期以来被认为是鲑鱼生态型的核心。不同的迁徙时间并不能阻止生态型之间的杂交，这是一个简单的、古老的多态性在不同种群中分离的结果。