Striking phenotypic variation yet low genetic differentiation in sympatric lake trout (Salvelinus namaycush)

The study of population differentiation in the context of ecological speciation is commonly assessed using populations with obvious discreteness. Fewer studies have examined diversifying populations with occasional adaptive variation and minor reproductive isolation, so factors impeding or facilitating the progress of early stage differentiation are less understood. We detected non-random genetic structuring in lake trout (Salvelinus namaycush) inhabiting a large, pristine, postglacial lake (Mistassini Lake, Canada), with up to five discernible genetic clusters having distinctions in body shape, size, colouration and head shape. However, genetic differentiation was low (FST = 0.017) and genetic clustering was largely incongruent between several population- and individual-based clustering approaches. Genotype- and phenotype-environment associations with spatial habitat, depth and fish community structure (competitors and prey) were either inconsistent or weak. Striking morphological vari...

在生态物种形成（ecological speciation）的研究框架中，种群分化的相关研究通常以具有明显离散特征的种群为研究对象。针对具备偶发性适应性变异与较弱生殖隔离的分化中种群的研究相对匮乏，因此阻碍或推动早期种群分化进程的相关调控因素仍未得到充分解析。本研究对栖息于加拿大大型原始未受干扰的冰后湖——米斯塔西尼湖（Mistassini Lake）的湖鳟（Salvelinus namaycush）展开分析，检测到其存在非随机的遗传结构：该种群可被划分为至多5个可辨识的遗传簇，这些遗传簇在体型、大小、体色与头部形态上均存在显著差异。然而，其遗传分化程度较低（FST = 0.017），且基于种群与基于个体的多种聚类分析方法所得到的遗传聚类结果整体上并不一致。基因型、表型与空间栖息地、水深以及鱼类群落结构（竞争者与猎物）之间的关联要么缺乏一致性，要么强度较弱。显著的形态学变异……