青藏高原东北部黄缨菊的谱系地理学

黄缨菊（Xanthopappus subacaulis）是青藏高原地区一种特有的高山草甸药用植物。为探讨第四纪冰期气候波动对黄缨菊居群遗传结构和空间分布格局的影响，对黄缨菊20个居群、123个个体的叶绿体DNA片段（psbA-trnH、rbcL和psbI-psbK）进行测序和数据分析。结果表明：黄缨菊居群共检测到6个单倍型，其中H1为古老单倍型，除居群P7外其余居群均具有单倍型H1，H3、H5和H6为特有单倍型，单倍型H3为居群P7的私有单倍型，单倍型H5和H6只存在于居群P18，单倍型H2和H4主要存在于青海湖流域的居群；总的遗传多样性（H_e）和核苷酸多样性（π）分别为3.101和0.008 903；居群间遗传变异（68.98%）大于居群内遗传变异（31.02%），居群间遗传分化较高（F_ST=0.689 85，P<0.01）；居群遗传分化系数N_ST（0.727）大于G_ST（0.656）（P>0.05），表明黄缨菊在分布区域内不存在明显的谱系地理结构；错配分布和中性检验结果显示，黄缨菊居群可能经历过近期扩张。据此，推测第四纪冰期黄缨菊可能在青海湖流域和甘肃临潭地区存在微型避难所，认为第四纪气候变迁及青藏高原隆升塑造了黄缨菊的现代地理分布格局。

Phylogeography of Xanthopappus subacaulis(Asteraceae), an Endemic Species from the Northeastern of the Qinghai-Tibet Plateau

Xanthopappus subacaulis is an endemic medicinal plant growing in the alpine meadow of the Qinghai-Tibet Plateau（QTP）. To explore the influence of Quaternary climatic oscillations on the population genetic structure and distribution pattern of X. subacaulis， 3 chloroplast DNA fragments（psbA-trnH， rbcL and psbI-psbK） from 123 individuals of 20 populations were sequenced and analyzed respectively in the present study. The results showed that 6 haplotypes were detected in X. subacaulis， among which H1 was an ancient haplotype. All populations of X. subacaulis had haplotype H1 except for P7. H3， H5 and H6 were private haplotypes， among which H3 was a private haplotype of population P7， and H5 and H6 only existed in P18. H2 and H4 were mainly distributed in the population of Qinghai Lake basin. The total genetic diversity（H_e） and nucleotide diversity（π） were 3.101 and 0.008 903， respectively. The genetic variation among populations（68.98%） was higher than that within populations（31.02%）， and the genetic differentiation among populations was relatively higher（F_ST=0.689 85，P<0.01）. The genetic differentiation coefficient N_ST of populations（0.727） was higher than that of G_ST（0.656）（P>0.05）， which indicated that there was no obvious phylogeographical structure in the sampling regions. The results of mismatch distributions and neutrality tests revealed that the population of X. subacaulis might have experienced recent expansion. Therefore， the study suggests there are micro-sanctuaries in Qinghai Lake basin of Qinghai Province and Lintan region of Gansu Province during the Quaternary glaciations， and suggests that the Quaternary climate change and QTP uplift shape the modern geographical distribution pattern of X. subacaulis.