Chloroplast DNA-based genetic diversity and phylogeography of Pyrus betulaefolia (Rosaceae) in Northern China
Chloroplast DNA-based genetic diversity and phylogeography of Pyrus betulaefolia (Rosaceae) in Northern China
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DOI：
10.1007/s11295-014-0718-0
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发表时间：
2014-03
影响因子：
2.4
通讯作者：
Y. Zong;P. Sun;Jing Liu;X. Yue;Q. Niu;Yuanwen Teng
中科院分区：
文献类型：
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作者：
Y. Zong;P. Sun;Jing Liu;X. Yue;Q. Niu;Yuanwen Teng
白梨是我国重要的野生梨树种之一，被认为是介于东西方梨类群之间的中间体。由于栖息地的破坏、碎片化和持续的开发，其种群数量正在减少，因此迫切需要采取保护和养护措施。对它的遗传多样性和系统地理进行评估是有效保护它的必要条件。利用两个叶绿体DNA基因间隔区片段，对18个野生稻的320个个体进行了遗传多样性和系统地理分析。白桦种群。对群体的单倍型变异、遗传分化和历史事件进行了估计。结果表明，P。中国北部的白桦种群具有较高的遗传多样性(HT= 0.826)。在所有18个群体中，显著的距离隔离值(r= 0.587，P<； 0.001，1,000个排列)表明遗传分化与地理距离之间存在相关性。根据遗传距离，在邻接树中识别出四个种群。分子变异分析表明，遗传变异主要存在于群体间，占总变异的64.61%。系统地理分析表明，该种群为OFP。白桦经历了一个范围迅速扩大的场景，这可能发生在608,000到204,580年前。同时，被距离隔离的受限基因流动和异地片段化都是形成OFP遗传模式的关键过程。白桦树。特定单倍型的出现可能归因于在OFP分布的北缘，祖先与其他梨属物种共同保持了祖先的遗传或保留了一种祖先多态。白桦树。具有较高单倍型多样性和独特单倍型的3个种群被认为是第四纪冰川的残留种群，应优先保护。另外三个较大的种群也应该通过建立自然保护区来优先保护。
Pyrus betulaefoliaBunge, considered as an intermediate between oriental and occidental pear groups, is one of the most important wild pear species. The number of its populations is decreasing because of habitat destruction, fragmentation, and continuous exploitation, so protection and conservation measures are urgently needed. Assessment of its genetic diversity and phylogeography are imperative for its efficient conservation. Two chloroplast DNA intergenic fragments were used to detect genetic diversity and phylogeography of 320 individuals from 18 wildP. betulaefoliapopulations. Haplotype variation, genetic differentiation, and historical events of the populations were estimated. The results showed thatP. betulaefoliapopulations sampled in northern China contained a high level of genetic diversity (HT= 0.826). A significant isolation-by-distance value (r= 0.587,P< 0.001, 1,000 permutations) among all 18 populations indicated a correlation between genetic divergence and geographic distance. Four population groups were identified in a neighbor-joining tree based on the genetic distance. Analyses of molecular variation showed that the genetic variation mainly existed among population groups, representing 64.61 % of the total variation. Phylogeographic analyses indicated that the populations ofP. betulaefoliaexperienced a scenario of rapid range expansion, which probably occurred between 608,000 and 204,580 years ago. Meanwhile, both the restricted gene flow with isolation by distance and allopatric fragmentation were crucial processes responsible for shaping the genetic patterns ofP. betulaefolia. The occurrence of specific haplotypes might be ascribed to an ancestral introgression or joint retention of an ancestral polymorphism with otherPyrusspecies at the northern edge of the distribution ofP. betulaefolia. Three populations displaying a high level of haplotype diversity and unique haplotypes were assumed to be relict populations of Quaternary glaciation and should have conservation priority. Three additional large populations should also be preferentially protected by building natural preservation zones.