基于线粒体COⅠ基因的中国沿海和泰国普吉岛里氏拟石磺群体遗传结构分析

Genetic structure and variation of Paraoncidium reevesii from the coastal area of China and Phuket Island of Thailand based on mtCOⅠ

通过对COI序列的分析，研究了中国沿海及泰国普吉岛8个里氏拟石磺群体的种群遗传结构，171个样本中共检测出单倍型101个，117个多态性位点，里氏拟石磺具有高的单倍型多样性（0．974±0．005）和核苷酸多样性（0．0322±0．0013）。分子方差分析（AMOVA）表明，50．99％的变异存在于种群间，49．01％的变异发生在种群内。群体间遗传分化固定指数（Fst）、基因流（Nm）及遗传距离分析表明，里氏拟石磺已明显分化为显著的遗传结构。遗传距离模式（IBD）检测显示，里氏拟石磺群体的遗传距离与地理距离之间不存在明显的线性关系。历史动态检验推断，湛江（zJ）、苍南（CN）、东寨港（HN）、文昌（WC）及普吉岛（TH）种群可能经历过历史上的种群扩张事件。中国沿海群体扩张时间推测大约为0．781～0．725Ma BP，泰国普吉岛群体约为0．035Ma BP，两者可能伴随更新世冰期的气候变暖、冰川消融和海平面上升等现象发生。

The genetic diversity and population genetic structure of Paraoncidium reevesii were investigated using mitochondrial cytochrome c oxidase subunit I （CO I ）gene sequences. A total of 171 individuals representing 8 collection sites were included in the analysis. Overall, 101 haplotypes were defined and 117 polymorphic sites were observed. The P. reevesii populations had high haplotype diversity （0. 974 -＋ 0. 005 ） and nucleotide diversity （0. 032 2 ＋ 0. 001 3）. The AMOVA test of P. reevesii populations based on haplotype frequencies revealed that 49.01% of the genetic variation occurred within the populations, whereas 50.99% of the genetic variation occurred among populations. Pairwise fixation index （ Fst ） , gene flow （ Nm ） and IBD analysis indicated significant genetic structure have appeared in P. reevesii populations. Demographic analyses indicated populations ZJ, CN, HN, WC and TH might have experienced population expansion,and the time of expansion of Chinese populations could be 0. 781 -0. 725 Ma BP,whereas the time of expansion of population TH could be 0. 035 Ma BP. The phenomenon might occur in Pleistocene period with melting of glaciers. changes of climate warming and rising of sea level.