青藏高原是气候变迁的敏感区。但第四纪以来全球气候的反复变化对该地区植物分布格局的影响至今未进行过仔细研究。线粒体DNA在松科植物中是母系遗传,其变异被广泛用于研究该科植物历史上由于气候变迁造成的瓶颈作用以及冰期后扩张中形成的奠基者效应。对青海云杉位于青藏高原核心、其边缘甘肃和宁夏地区共12个种群155个个体的线粒体nad 1片段的全序列进行测序,研究该序列在各种群中的变异状况。通过测序发现该片段在青海云杉中十分保守,在所有个体中仅发现由于重复序列造成的5种单倍型(H ap A,H ap B,H ap C,H ap D和H ap E)。高原核心的所有种群均只有H ap A,而所有的4种单倍型都在高原边缘的甘肃地区存在,但这一地区仍然是H ap A占优势;但是在远离高原的宁夏地区则存在5种单倍性;多样性的变异趋势是宁夏地区高于高原边缘的甘肃地区,而甘肃地区又显著高于高原核心地区。这一结果表明,在过去气候变迁过程中,不同地区的青海云杉种群经历了不同的气候影响,这种影响造成的奠基者效应或者瓶颈作用是造成目前这种遗传多样性分布格局的主要原因。现有的单倍型分布格局,特别是高原上所有间断分布种群拥有相同的单倍型表明,森林回迁中的奠基者效应应是更为重要的因素。
Phragmites australis is a cosmopolitan clonal species, but one haplotype from Eurasia has become highly invasive in North America. This article describes an investigation of the phylogeographic composition of 77 populations from China, based on the sequencing of two chloroplast non-coding DNA regions. A total of 11 haplotypes were detected, based on the sequence alignments of two chloroplast DNA fragments from 421 sampled individuals. Six of these haplotypes were completely new, and did not correspond to any of this species＇ 27 previously known haplotypes. The invasive haplotype M and haplotypes O and P were shown to occur frequently. Haplotype O is widely distributed across all regions and probably represents the primitive haplotype of this species. In contrast, P is mainly distributed in the humid eastern and northeastern regions of China, whereas M is more frequent in western and northwestern China-arid habitats with low precipitation. Between eastern and northeastern and western and northwestern regions, there was distinct genetic differentiation; the former region has a higher genetic diversity than the latter. The high occurrence of haplotype M in western China suggests that it prefers more arid habitats. These findings shed new light on the native distribution, adaptation, and habitat preference of haplotype M, which invaded North America.
