Yang Aihong, Zhong Yongda, Liu Shujuan, Liu Lipan, Liu Tengyun, Li Yanqiang, Yu Faxin
The Key Laboratory of Horticultural Plant Genetic and Improvement of Jiangxi, Institute of Biological Resources, Jiangxi Academy of Sciences, Nanchang, Jiangxi, China.
PeerJ. 2019 Feb 1;7:e6355. doi: 10.7717/peerj.6355. eCollection 2019.
Subtropical China is a global center of biodiversity and one of the most important refugia worldwide. Mountains play an important role in conserving the genetic resources of species. is a Tertiary relict tree largely endemic to subtropical China. In this study, we aimed to achieve a better understanding of the phylogeographical pattern of and to explore the role of mountains in the conservation of genetic resources.
Three chloroplast regions (J-A, 32-F, and K5'-K) were sequenced in 40 populations of for phylogeographical analyses. Relationships among chloroplast DNA (cpDNA) haplotypes were determined using median-joining networks, and genetic structure was examined by spatial analysis of molecular variance (SAMOVA). The ancestral area of the species was reconstructed using the Bayesian binary Markov Chain Monte Carlo (BBM) method according to its geographic distribution and a maximum parsimony (MP) tree based on Bayesian methods.
Obvious phylogeographic structure was found in . SAMOVA revealed seven groups matching the major landscape features of the distribution area. The haplotype network showed three clades distributed in the eastern, southwestern, and northwestern regions. Separate northern and southern refugia were found in the Wu Mountains and Yungui Plateau, with genetic admixture in the Dalou Mountains and Wuling Mountains. BBM revealed a more ancient origin of in the eastern region, with a west-east split most likely having occurred during the Mindel glacial stage.
The clear geographical distributions of haplotypes suggested multiple mountainous refugia of . The east-west lineage split was most likely a process of gradual genetic isolation and allopatric lineage divergence when the Nanling corridor was frequently occupied by evergreen or coniferous forest during Late Quaternary oscillations. Hotspots of haplotype diversity in the Dalou Mountains and Wuling Mountains likely benefited from gene flow from the Wu Mountains and Yungui Plateau. Collectively, these results indicate that mountain regions should be the main units for conserving and collecting genetic resources of and other similar species in subtropical China.
中国亚热带地区是全球生物多样性中心之一，也是世界上最重要的避难所之一。山脉在保护物种遗传资源方面发挥着重要作用。[物种名称]是一种主要分布于中国亚热带地区的第三纪孑遗树种。在本研究中，我们旨在更好地了解[物种名称]的系统发育地理格局，并探讨山脉在保护[物种名称]遗传资源中的作用。
对[物种名称]的40个种群的三个叶绿体区域（J-A、32-F和K5'-K）进行测序，以进行系统发育地理分析。使用中介网络确定叶绿体DNA（cpDNA）单倍型之间的关系，并通过分子方差空间分析（SAMOVA）研究遗传结构。根据其地理分布和基于贝叶斯方法的最大简约（MP）树，使用贝叶斯二元马尔可夫链蒙特卡罗（BBM）方法重建该物种的祖先区域。
在[物种名称]中发现了明显的系统发育地理结构。SAMOVA揭示了与[物种名称]分布区主要地貌特征相匹配的七个组。单倍型网络显示三个分支分布在东部、西南部和西北部地区。在巫山和云贵高原发现了单独的北方和南方避难所，在大娄山和武陵山存在遗传混合。BBM揭示了[物种名称]在东部地区起源更为古老，最有可能在明德冰期阶段发生了由西向东的分裂。
单倍型的明确地理分布表明[物种名称]存在多个山区避难所。东西谱系分裂很可能是在第四纪晚期振荡期间南岭走廊经常被常绿或针叶林占据时，逐渐遗传隔离和异域谱系分化的过程。大娄山和武陵山单倍型多样性热点可能受益于来自巫山和云贵高原的基因流动。总体而言，这些结果表明山区应该是保护和收集中国亚热带地区[物种名称]和其他类似物种遗传资源的主要单元。
