基于叶绿体基因序列rbcL-accD研究莛子藨的分子遗传多样性和谱系地理结构

Gnentic Diversity and Phylogeographic Structure of Triosteum pinnatifidum based Chloroplast DNA Sequence rbcL-accD

莛子藨是莛子藨属的一种多年生草本植物,主要分布在青藏高原东北部及邻近高山地区和日本,为东亚特有种。本文基于叶绿体DNA基因间隔区rbcL-accD序列,对莛子藨物种水平的序列特征、分子遗传多样性和谱系地理结构进行研究。分析结果发现该区域莛子藨种群的遗传变异主要来自于居群间(72.28%),优势单倍型(H2)广泛分布,特有单倍型分散在多个居群。居群间遗传分化系数N_(ST)<G_(ST),没有检测到显著谱系地理结构,而且居群间基因流较低(N_m=0.096),青藏高原及其邻近地区特殊地形和生态环境造成的地理隔离或者生境异质化可能是现有单倍型分布格局形成的原因。种群动态历史分析显示莛子藨经历过不显著的种群选择或者扩张事件,综合分析推测莛子藨居群应该是在间冰期或者冰期后从不同避难所扩散形成现在的分布格局,具体避难所还需进一步深入研究才能确认。

Triosteum pinnatifidum is perennial herb belonging to Triosteum （Caprifoliaceae） with the distribution in northwest Qinghai-Tibetan Plateau and adjacent mountain regions and Japan. It＇ s endemic species of East Asia. We studied the sequence features, genetic variation and phylogeographic structure of T. pinnatifidum based on chloroplast DNA intergenic region rbcL-accD. Analysis of molecular variance for the whole populations revealed that 72.28% of total genetic variation occurred among populations, and 27.72% within populations. Dominant haplotype H2 had wide distribution while the private haplotypes could be found in different populations. There was no phylogeographic structure （ NsT 〈 （;ST） and low gene flow （ N,,, = 0. 096 ）, indicating the geographic isolation and variable habitat created by the special topography or ecological environment on the Qinghai-Tibetan Plateau and adjacent mountain regions may form current distribution of haplotypes. T. pinnatifidum experienced nonsignificant species selection or expansion. Indeed, we speculate there were different refugias for T. pinnatifidum during glaciations, it spread to current locations during interglaciation or postglaciation. To know the details of refuges and the migration routes, more work are needed in future survey.