Zhao Xingfeng, Ma Yongpeng, Sun Weibang, Wen Xiangying, Milne Richard
Kunming Botanical Garden, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650204, China.
Fauna & Flora International China Programme, Beijing 100101, China.
Int J Mol Sci. 2012;13(4):4396-4411. doi: 10.3390/ijms13044396. Epub 2012 Apr 10.
Michelia coriacea, a critically endangered tree, has a restricted and fragmented distribution in Southeast Yunnan Province, China. The genetic diversity, genetic structure and gene flow in the three extant populations of this species were detected by 10 inter-simple sequence repeat (ISSR) markers and 11 simple sequence repeat (SSR) markers. Examination of genetic diversity revealed that the species maintained a relatively high level of genetic diversity at the species level (percentage of polymorphic bands) PPB = 96.36% from ISSRs; PPL (percentage of polymorphic loci) = 95.56% from SSRs, despite several fragmental populations. Low levels of genetic differentiation among the populations of M. coriacea were detected by Nei's G(st) = 0.187 for ISSR and Wright's F(st) = 0.090 for SSR markers, which is further confirmed by Bayesian model-based STRUCTURE and PCoA analysis that could not reveal a clear separation between populations, although YKP was differentiated to other two populations by ISSR markers. Meanwhile, AMOVA analysis also indicated that 22.84% and 13.90% of genetic variation existed among populations for ISSRs and SSRs, respectively. The high level of genetic diversity, low genetic differentiation, and the population, structure imply that the fragmented habitat and the isolated population of M. coriacea may be due to recent over-exploitation. Conservation and management of M. coriacea should concentrate on maintaining the high level of genetic variability through both in and ex-situ conservation actions.
深山含笑是一种极度濒危的树种，在中国云南省东南部的分布范围狭窄且呈碎片化。利用10个简单重复序列区间（ISSR）标记和11个简单序列重复（SSR）标记，对该物种现存的三个种群的遗传多样性、遗传结构和基因流进行了检测。遗传多样性检测结果显示，尽管有几个碎片化种群，但该物种在物种水平上仍保持着较高的遗传多样性：来自ISSR的多态性条带百分比（PPB）= 96.36%；来自SSR的多态性位点百分比（PPL）= 95.56%。通过Nei氏G（st）= 0.187（ISSR）和Wright氏F（st）= 0.090（SSR标记）检测到深山含笑种群间的遗传分化水平较低，基于贝叶斯模型的STRUCTURE和主坐标分析（PCoA）进一步证实了这一点，尽管通过ISSR标记，YK种群与其他两个种群有所分化，但仍无法清晰地将种群区分开来。同时，方差分析（AMOVA）也表明，对于ISSR和SSR，分别有22.84%和13.90%的遗传变异存在于种群间。遗传多样性水平高、遗传分化低以及种群结构表明，深山含笑栖息地的碎片化和种群的隔离可能是近期过度开发所致。深山含笑的保护和管理应集中于通过就地和迁地保护行动来维持高水平的遗传变异性。
