Adaptive genetic variation distinguishes Chilean blue mussels (Mytilus chilensis) from different marine environments

Chilean mussel populations have been thought to be panmictic with limited genetic structure. Genotyping-by-sequencing approaches have enabled investigation of genome-wide variation that may better distinguish populations that have evolved in different environments. We investigated neutral and adaptive genetic variation in Mytilus from six locations in southern Chile with 1,240 SNP obtained with RAD-seq. Differentiation among locations with 891 neutral SNPs was low (FST = 0.005). Higher differentiation was obtained with a panel of 58 putative outlier SNPs (FST = 0.114) indicating the potential for local adaptation. This panel identified clusters of genetically related individuals and demonstrated that much of the differentiation (~92%) could be attributed to the three major regions and environments: extreme conditions in Patagonia, inner bay influenced by aquaculture (Reloncaví́), and outer bay (Chiloé Island). Patagonia samples were most distinct, but additional analysis carried out exc...

智利贻贝种群此前被认为是泛交种群，仅具有有限的遗传结构。测序分型（Genotyping-by-sequencing, GBS）技术的应用，使得研究者得以开展全基因组变异分析，进而更好地区分在不同环境中演化的种群。本研究借助限制性位点相关DNA测序（Restriction-site Associated DNA sequencing, RAD-seq）获得的1240个单核苷酸多态性（Single Nucleotide Polymorphism, SNP）位点，对智利南部6个采样点的贻贝属（Mytilus）种群的中性遗传变异与适应性遗传变异进行了分析。基于891个中性SNP位点计算得到的种群间遗传分化程度较低（固定指数FST=0.005）。而针对由58个潜在异常SNP位点组成的位点集进行分析时，得到了更高的遗传分化水平（FST=0.114），这表明智利贻贝具备局部适应的潜力。该异常位点集成功鉴定出了遗传亲缘关系相近的个体类群，并证实绝大多数遗传分化（约92%）可归因于三大主要区域及其对应的环境特征：巴塔哥尼亚的极端环境、受水产养殖影响的内湾（伦卡维湾，Reloncaví）以及外湾（奇洛埃岛海域）。巴塔哥尼亚的采样种群分化最为显著，但后续补充分析仍在进行中（原文此处截断）。