Institute of Molecular Ecology, The MOE Key Laboratory of Arid and Grassland Ecology, College of Life Science, Lanzhou University, Lanzhou, Gansu, China.
Mol Biol Evol. 2010 May;27(5):1001-14. doi: 10.1093/molbev/msp301. Epub 2009 Dec 22.
Nucleotide variation at 12-16 nuclear loci was studied in three spruce species from the Qinghai-Tibetan Plateau (QTP), Picea likiangensis, P. wilsonii, and P. purpurea, and one species from the Tian Shan mountain range, P. schrenkiana. Silent nucleotide diversity was limited in P. schrenkiana and high in the three species from the QTP, with values higher than in boreal spruce species, despite their much more restricted distributions compared with that of the boreal species. In contrast to European boreal species that have experienced severe bottlenecks in the past, coalescent-based analysis suggests that DNA polymorphism in the species from the QTP and adjacent areas is compatible with the standard neutral model (P. likiangensis, P. wilsonii, and P. schrenkiana) or with population growth (P. purpurea). In order to test if P. purpurea is a diploid hybrid of P. likiangensis and P. wilsonii, we used a combination of approaches, including model-based inference of population structure, isolation-with-migration models, and recent theoretical results on the effect of introgression on the geographic distribution of diversity. In contrast to the three other species, each of which was predominantly assigned to a single cluster in the Structure analysis, P. purpurea individuals were scattered over the three main clusters and not, as we had expected, confined to the P. likiangensis and P. wilsonii clusters. Furthermore, the contribution of P. schrenkiana was by far the largest one. In agreement with this, the divergence between P. purpurea and P. schrenkiana was lower than the divergence of either P. likiangensis or P. wilsonii from P. schrenkiana. These results, together with previous ones showing that P. purpurea and P. wilsonii share the same haplotypes at both chloroplast and mitochondrial markers, suggest that P. purpurea has a complex origin, possibly involving additional species.
在青藏高原（QTP）的三种云杉物种（丽江云杉、川西云杉和紫果云杉）和天山山脉的一种云杉物种（帕米尔云杉）中，研究了 12-16 个核基因座的核苷酸变异。尽管其分布范围比北方的云杉物种要小得多，但帕米尔云杉的沉默核苷酸多样性有限，而 QTP 的三个物种的多样性则很高，其值高于北方的云杉物种。与过去经历过严重瓶颈的欧洲北方物种不同，基于合并分析的结果表明，来自 QTP 及其周边地区的物种的 DNA 多态性与标准中性模型（丽江云杉、川西云杉和帕米尔云杉）一致，或者与种群增长（紫果云杉）一致。为了测试紫果云杉是否是丽江云杉和川西云杉的二倍体杂种，我们结合使用了一些方法，包括种群结构的基于模型的推断、隔离与迁移模型，以及最近关于基因渗入对多样性地理分布影响的理论结果。与其他三个物种不同，每个物种在结构分析中主要被分配到一个单一的聚类中，而紫果云杉的个体则分散在三个主要的聚类中，而不是像我们预期的那样局限于丽江云杉和川西云杉的聚类中。此外，帕米尔云杉的贡献是迄今为止最大的。这与我们的预期相符，紫果云杉与帕米尔云杉之间的分化程度低于丽江云杉或川西云杉与帕米尔云杉之间的分化程度。这些结果与之前的研究结果一致，表明紫果云杉和川西云杉在叶绿体和线粒体标记上共享相同的单倍型，这表明紫果云杉的起源复杂，可能涉及其他物种。
