Waters Charles D, Clemento Anthony, Aykanat Tutku, Garza John Carlos, Naish Kerry A, Narum Shawn, Primmer Craig R
School of Aquatic and Fishery Sciences, University of Washington, Seattle, WA, USA.
Institute of Marine Sciences, University of California, Santa Cruz, CA, USA.
Mol Ecol. 2021 Mar;30(6):1435-1456. doi: 10.1111/mec.15822. Epub 2021 Mar 8.
Understanding the genetic basis of repeated evolution of the same phenotype across taxa is a fundamental aim in evolutionary biology and has applications in conservation and management. However, the extent to which interspecific life-history trait polymorphisms share evolutionary pathways remains underexplored. Here, we address this gap by studying the genetic basis of a key life-history trait, age at maturity, in four species of Pacific salmonids (genus Oncorhynchus) that exhibit intra- and interspecific variation in this trait-Chinook Salmon, Coho Salmon, Sockeye Salmon, and Steelhead Trout. We tested for associations in all four species between age at maturity and two genome regions, six6 and vgll3, that are strongly associated with the same trait in Atlantic Salmon (Salmo salar). We also conducted a genome-wide association analysis in Steelhead to assess whether additional regions were associated with this trait. We found the genetic basis of age at maturity to be heterogeneous across salmonid species. Significant associations between six6 and age at maturity were observed in two of the four species, Sockeye and Steelhead, with the association in Steelhead being particularly strong in both sexes (p = 4.46 × 10 after adjusting for genomic inflation). However, no significant associations were detected between age at maturity and the vgll3 genome region in any of the species, despite its strong association with the same trait in Atlantic Salmon. We discuss possible explanations for the heterogeneous nature of the genetic architecture of this key life-history trait, as well as the implications of our findings for conservation and management.
了解同一表型在不同分类群中反复进化的遗传基础是进化生物学的一个基本目标，并且在保护和管理方面具有应用价值。然而，种间生活史性状多态性共享进化途径的程度仍未得到充分探索。在这里，我们通过研究太平洋鲑科（Oncorhynchus属）四个物种中一个关键生活史性状——成熟年龄的遗传基础来填补这一空白，这四个物种在该性状上表现出种内和种间变异，即奇努克鲑、银鲑、红鲑和虹鳟。我们测试了这四个物种中成熟年龄与两个基因组区域six6和vgll3之间的关联，这两个区域与大西洋鲑（Salmo salar）的同一性状密切相关。我们还在虹鳟中进行了全基因组关联分析，以评估是否有其他区域与该性状相关。我们发现成熟年龄的遗传基础在鲑科物种中是异质的。在四个物种中的两个物种，即红鲑和虹鳟中，观察到six6与成熟年龄之间存在显著关联，虹鳟中两性的关联尤其强烈（在调整基因组膨胀后，p = 4.46 × 10）。然而，尽管vgll3基因组区域与大西洋鲑的同一性状密切相关，但在任何物种中均未检测到成熟年龄与vgll3基因组区域之间存在显著关联。我们讨论了这一关键生活史性状遗传结构异质性的可能解释，以及我们的发现对保护和管理的意义。
