Koch Ilana J, Narum Shawn R
Columbia River Inter-Tribal Fish Commission Hagerman ID USA.
Evol Appl. 2020 Jun 8;13(9):2316-2332. doi: 10.1111/eva.13026. eCollection 2020 Oct.
Recent studies have begun to elucidate the genetic basis for phenotypic traits in salmonid species, but many questions remain before these candidate genes can be directly incorporated into conservation management. In Chinook Salmon (), a region of major effect for migration timing has been discovered that harbors two adjacent candidate genes (greb1L, rock1), but there has been limited work to examine the association between these genes and migratory phenotypes at the individual, compared to the population, level. To provide a more thorough test of individual phenotypic association within lineages of Chinook Salmon, 33 candidate markers were developed across a 220 Kb region on chromosome 28 previously associated with migration timing. Candidate and neutral markers were genotyped in individuals from representative collections that exhibit phenotypic variation in timing of arrival to spawning grounds from each of three lineages of Chinook Salmon. Association tests confirmed the majority of markers on chromosome 28 were significantly associated with arrival timing and the strongest association was consistently observed for markers within the rock1 gene and the intergenic region between greb1L and rock1. Candidate markers alone explained a wide range of phenotypic variation for Lower Columbia and Interior ocean-type lineages (29% and 78%, respectively), but less for the Interior stream-type lineage (5%). Individuals that were heterozygous at markers within or upstream of rock1 had phenotypes that suggested a pattern of dominant inheritance for early arrival across populations. Finally, previously published fitness estimates from the Interior stream-type lineage enabled tests of association with arrival timing and two candidate markers, which revealed that fish with homozygous mature genotypes had slightly higher fitness than fish with premature genotypes, while heterozygous fish were intermediate. Overall, these results provide additional information for individual-level genetic variation associated with arrival timing that may assist with conservation management of this species.
最近的研究已开始阐明鲑科物种表型性状的遗传基础，但在这些候选基因能够直接纳入保护管理之前，仍有许多问题有待解决。在奇努克鲑（）中，已发现一个对洄游时间有主要影响的区域，该区域包含两个相邻的候选基因（greb1L、rock1），但与种群水平相比，在个体水平上研究这些基因与洄游表型之间关联的工作还很有限。为了更全面地测试奇努克鲑谱系内个体表型的关联，在28号染色体上一个先前与洄游时间相关的220千碱基区域开发了33个候选标记。对来自具有代表性样本的个体进行候选标记和中性标记基因分型，这些样本展示了奇努克鲑三个谱系中每个谱系到达产卵地时间的表型变异。关联测试证实，28号染色体上的大多数标记与到达时间显著相关，并且在rock1基因以及greb1L和rock1之间的基因间区域内的标记始终观察到最强的关联。仅候选标记就解释了下哥伦比亚和内陆海洋型谱系广泛的表型变异（分别为29%和78%），但对内陆溪流型谱系的解释较少（5%）。在rock1内或其上游标记处杂合的个体具有的表型表明，早到达在种群中存在显性遗传模式。最后，先前发表的内陆溪流型谱系的适应性估计值使得能够测试与到达时间和两个候选标记的关联，结果显示纯合成熟基因型的鱼比早熟基因型的鱼适应性略高，而杂合鱼则介于两者之间。总体而言，这些结果为与到达时间相关的个体水平遗传变异提供了更多信息，这可能有助于该物种的保护管理。
