基于叶绿体DNA非编码序列的蒙古扁桃谱系地理学研究

Molecular Phylogeography of Amygdalus mongolica(Rosaceae) Based on Chloroplast DNA Non-coding Sequences

该研究选取中国西北干旱区第三纪孑遗植物蒙古扁桃(Amygdalus mongolica),基于叶绿体DNA非编码trnH-psbA序列对蒙古扁桃17个居群324个个体进行了谱系地理学研究。结果表明:(1)蒙古扁桃trnH-psbA序列长度350bp,变异位点63个,共有9种单倍型,居群间总遗传多样性为(Ht)为0.758,居群内平均遗传多样性为(Hs)为0.203,贺兰山东麓及阴山南麓边缘的居群具有较高的单倍型多样性及核苷酸多样性并固定较多特有单倍型,推测这2个地区是蒙古扁桃在第四纪冰期时的重要避难所。(2)AMOVA分析表明,居群间的遗传变异为83.84%,居群内的遗传变异为16.16%,居群间遗传分化系数Nst>Gst(Nst=0.733,Gst=0.655,P>0.05),表明蒙古扁桃不存在明显的谱系地理结构;根据单倍型地理分布及网络关系图,把蒙古扁桃自然地理居群分为东、西两大地理组群,而且东、西地理组群没有共享单倍型;居群遗传结构分析表明,两大地理组群遗传分化较大。(3)蒙古扁桃居群在间冰期或冰期后经历了近期的居群扩张,由于奠基者效应使得多数居群只固定了单一的单倍型。

Amygdalus mongolicais a Tertiary relict plants widely distributed on the arid region of Northwest China,non-coding chloroplast DNA was amplified and sequenced in 324 individuals from 17 populations sampled from the entire distribution range of A.mongolica.The main results are as follows：（1）the length of trnH-psbA sequence was 350 bp,a total of 63 polymorphic sites were identified and 9 haplotypes were recovered.Total genetic diversity was 0.758,average genetic diversity within populations was0.203.Populations from the Helan Mountains and southern foot of Yin Mountain owned high haplotype diversity and nucleotide diversity and fixed more private haplotypes,which suggested that the eastern margin of the Helan Mountains and southern foot of Yin Mountain were important refugium during the Quaternary glaciation.（2）AMOVA analysis suggest that 83.84%of total variation existed among populations and 16.16%existed within population,there is no significant phylogeographic structure（Nst=0.733,Gst=0.655,P〉0.05）.The natural populations of A.mongolica could be divided into eastern group and western group based on the geographical distribution and network of haplotypes,there were no shared cpDNA haplotypes between the two groups.The high level of genetic differentiation and genetic diversity were found based on the population genetic analysis,and no significant phylogeography was existed in the populations of A.mongolica.（3）The populations of A.mongolicahave occurred the expansion events during the interglacial periods or post-glacial.Founder effect occurred during the population expansion which lead to only one haplotype in the most populations.