The genetic underpinnings of incipient speciation, including the genomic mechanisms which contribute to morphological and ecological differentiation and reproductive isolation, remain poorly understood. The repeated evolution of consistently, phenotypically distinct morphs of Arctic Charr (Salvelinus alpinus) within the Quaternary period offer an ideal model to study the repeatability of evolution at the genomic level. Sympatric morphs of Arctic Charr are found across this species' circumpolar distribution. However, the specific genetic mechanisms driving this morph differentiation are largely unknown despite the cultural and economic importance of the anadromous morph. We used a newly designed 87k SNP chip to investigate the character and consistency of the genomic differences among sympatric morphs within three recently deglaciated and geographically proximate lakes in Labrador, Canada. We found genetically distinct small and large morph Arctic Charr in all three lakes consistent with resident and anadromous morphs, respectively. A degree of reproductive isolation among sympatric morphs is likely given genome‐wide distributions of outlier SNPs and high genome‐wide F_STs. Across all lakes, outlier SNPs were largely nonoverlapping suggesting a lack of genetic parallelism driving morph differentiation. Alternatively, several genes and paralogous copies of the same gene consistently differentiated morphs across multiple lakes suggesting their importance to the manifestation of morphs. Our results confirm the utility of Arctic Charr as a model for investigating the predictability of evolution and support the importance of both genetic parallelism and nonparallelism to the incipient speciation of Arctic Charr morphs.

中文翻译：

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有限的遗传平行性是北极鱼类（Salvelinus alpinus）地理上最近的种群最近反复形成物种的基础。

最初形成物种的遗传基础，包括有助于形态和生态分化以及生殖分离的基因组机制，仍然知之甚少。北极Charr（Salvelinus alpinus）的一致，在表型上不同的形态的重复演化）在第四纪期间提供了一个理想的模型，可用于研究基因组水平上进化的可重复性。在该物种的旋极分布中发现了北极Charr的同胞形态。然而，尽管该异常形态的文化和经济重要性，但驱动这种形态分化的具体遗传机制仍是未知之数。我们使用了新设计的87k SNP芯片，研究了加拿大拉布拉多最近三个冰川和地理位置最接近的湖泊中同胞形态之间基因组差异的特征和一致性。我们在所有三个湖泊中发现了在遗传上明显不同的小和大变体北极Charr，分别与常驻和异常形态一致。F _ST s。在所有湖泊中，异常的SNP在很大程度上不重叠，表明缺乏遗传并行性驱动形态分化。或者，几个基因和同一基因的旁系同源拷贝在多个湖泊之间持续分化出不同的形态，表明它们对形态表达的重要性。我们的研究结果证实了北极CHARR作为研究进化可预测性的模型的效用，并支持遗传平行性和非平行性对北极Charr形态的初始物种形成的重要性。