State Key Laboratory of Grassland Agro-Ecosystems, School of Life Sciences, Lanzhou University, Lanzhou 730000, China.
Ann Bot. 2013 Dec;112(9):1829-44. doi: 10.1093/aob/mct241. Epub 2013 Nov 11.
Genetic drift due to geographical isolation, gene flow and mutation rates together make it difficult to determine the evolutionary relationships of present-day species. In this study, population genetic data were used to model and decipher interspecific relationships, speciation patterns and gene flow between three species of spruce with similar morphology, Picea wilsonii, P. neoveitchii and P. morrisonicola. Picea wilsonii and P. neoveitchii occur from central to north-west China, where they have overlapping distributions. Picea morrisonicola, however, is restricted solely to the island of Taiwan and is isolated from the other two species by a long distance.
Sequence variations were examined in 18 DNA fragments for 22 populations, including three fragments from the chloroplast (cp) genome, two from the mitochondrial (mt) genome and 13 from the nuclear genome.
In both the cpDNA and the mtDNA, P. morrisonicola accumulated more species-specific mutations than the other two species. However, most nuclear haplotypes of P. morrisonicola were shared by P. wilsonii, or derived from the dominant haplotypes found in that species. Modelling of population genetic data supported the hypothesis that P. morrisonicola derived from P. wilsonii within the more recent past, most probably indicating progenitor-derivative speciation with a distinct bottleneck, although further gene flow from the progenitor to the derivative continued. In addition, the occurrence was detected of an obvious mtDNA introgression from P. neoveitchii to P. wilsonii despite their early divergence.
The extent of mutation, introgression and lineage sorting taking place during interspecific divergence and demographic changes in the three species had varied greatly between the three genomes. The findings highlight the complex evolutionary histories of these three Asian spruce species.
由于地理隔离、基因流和突变率导致的遗传漂变，使得确定当今物种的进化关系变得困难。本研究利用种群遗传数据来构建和解析三种形态相似的云杉（Picea wilsonii、P. neoveitchii 和 P. morrisonicola）种间关系、物种形成模式和基因流。Picea wilsonii 和 P. neoveitchii 分布在中国中西部到西北部，分布区域有重叠。然而，P. morrisonicola 仅局限于台湾岛，与其他两个物种相隔甚远。
对来自叶绿体（cp）基因组的三个片段、线粒体（mt）基因组的两个片段和核基因组的 13 个片段的 22 个种群的 22 个种群进行了序列变异检测。
在 cpDNA 和 mtDNA 中，P. morrisonicola 的种间特异性突变积累比其他两个物种多。然而，P. morrisonicola 的大多数核单倍型与 P. wilsonii 共享，或者是由该物种中占主导地位的单倍型衍生而来。种群遗传数据的建模支持了以下假说：P. morrisonicola 是在更近的过去从 P. wilsonii 衍生而来的，最有可能是在明显瓶颈作用下发生的祖先进化，尽管从祖先进化到衍生物的进一步基因流仍在继续。此外，尽管 P. neoveitchii 和 P. wilsonii 分化较早，但仍检测到明显的 mtDNA 渐渗。
在三个物种的种间分化和种群动态变化过程中，突变、渐渗和谱系分化的程度在三个基因组之间存在很大差异。研究结果突显了这三个亚洲云杉物种复杂的进化历史。
