Perreault-Payette Alysse, Muir Andrew M, Goetz Frederick, Perrier Charles, Normandeau Eric, Sirois Pascal, Bernatchez Louis
Département de Biologie, Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, 1030 avenue de la Médecine, Québec, Quebec, Canada G1V 0A6, Canada.
Department of Fisheries and Wildlife, Michigan State University, 13 Natural Resources Building, East Lansing, MI, 48824, USA.
Mol Ecol. 2017 Mar;26(6):1477-1497. doi: 10.1111/mec.14018. Epub 2017 Feb 18.
Understanding the emergence of species through the process of ecological speciation is a central question in evolutionary biology which also has implications for conservation and management. Lake trout (Salvelinus namaycush) is renowned for the occurrence of different ecotypes linked to resource and habitat use throughout North America. We aimed to unravel the fine genetic structure of the four lake trout ecotypes in Lake Superior. A total of 486 individuals from four sites were genotyped at 6822 filtered SNPs using RADseq technology. Our results revealed different extent of morphological and genetic differentiation within the different sites. Overall, genetic differentiation was weak but significant and was on average three times higher between sites (mean F = 0.016) than between ecotypes within sites (mean F = 0.005) indicating higher level of gene flow or a more recent shared ancestor between ecotypes within each site than between populations of the same ecotype. Evidence of divergent selection was also found between ecotypes and/or in association with morphological variation. Outlier loci found in genes related to lipid metabolism and visual acuity were of particular interest in this context of ecotypic divergence. However, we did not find clear indication of parallelism at the genomic level, despite the presence of phenotypic parallelism among some ecotypes from different sampling sites. Overall, the occurrence of different levels of both genomic and phenotypic differentiation between ecotypes within each site with several differentiated loci linked to relevant biological functions supports the presence of a continuum of divergence in lake trout.
通过生态物种形成过程来理解物种的出现是进化生物学中的核心问题，这对保护和管理也具有重要意义。湖鳟（Salvelinus namaycush）因在北美各地出现与资源和栖息地利用相关的不同生态型而闻名。我们旨在揭示苏必利尔湖四种湖鳟生态型的精细遗传结构。使用RADseq技术，对来自四个地点的486个个体在6822个经过筛选的单核苷酸多态性位点进行了基因分型。我们的结果揭示了不同地点内形态和遗传分化的不同程度。总体而言，遗传分化较弱但显著，不同地点之间的平均遗传分化（平均F = 0.016）是同一地点内不同生态型之间平均遗传分化（平均F = 0.005）的三倍左右，这表明每个地点内不同生态型之间的基因流水平更高或有更近的共同祖先，而不是同一生态型的不同种群之间。在不同生态型之间和/或与形态变异相关联的情况下，也发现了趋异选择的证据。在与脂质代谢和视力相关的基因中发现的异常位点在这种生态型分化的背景下特别令人感兴趣。然而，尽管来自不同采样地点的一些生态型之间存在表型平行性，但我们在基因组水平上未发现明显的平行性迹象。总体而言，每个地点内不同生态型之间存在不同水平的基因组和表型分化，且有几个分化位点与相关生物学功能相关，这支持了湖鳟存在连续分化的观点。
