Phylogeographic analysis of a temperate-deciduous forest restricted plant (Bupleurum longiradiatum Turcz.) reveals two refuge areas in China with subsequent refugial isolation promoting speciation.
Phylogeographic analysis of a temperate-deciduous forest restricted plant (Bupleurum longiradiatum Turcz.) reveals two refuge areas in China with subsequent refugial isolation promoting speciation.
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DOI：
10.1016/j.ympev.2013.04.007
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发表时间：
2013-09
影响因子：
4.1
通讯作者：
Cai Zhao;Chang‐Bao Wang;Xiang‐Guang Ma;Qianlong Liang;Xingjin He
中科院分区：
文献类型：
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作者：
Cai Zhao;Chang‐Bao Wang;Xiang‐Guang Ma;Qianlong Liang;Xingjin He
本研究调查了气候引起的波动和复杂的地质条件对东亚大陆目前支离破碎的温带森林栖息地中物种形成的进化过程的影响。除此之外，我们还调查了一个备受争议的问题：温带森林是否在冰期期间向南迁移，或者华北地区是否存在避难所，使得温带森林在该地区局部生存。为了实现这些目标，我们对长叶柴胡 (Bupleurum longiradiatum Turcz) 的系统发育地理学进行了调查。 （一种仅生长于温带森林的草本植物）由三个叶绿体 (cp) DNA 片段的序列变异构建：trnL–trnF、psbA–trnH 和 rps16。我们的分析显示物种内具有较高的遗传多样性（hT = 0.948），并且群体（黄色和紫色花）之间具有显着的遗传分化，具有显着的系统发育地理模式（NST>GST，P<0.05）。鉴定出四十三个单倍型并聚类成两个谱系（紫花谱系和黄花谱系）。在长柴胡的整个分布范围内发现了两个相应的避难区，一个在秦岭及其邻近地区，一个在长白山/中国东部。这些结果为这样的假设提供了证据：在末次盛冰期或早期寒冷时期，中国北方温带森林范围内维持着独立的保护区。长叶柴胡紫菜根据分子数据形成了一个单一的分类单元。这种特定的形成过程表明，历史变差因素，即气候通过温带落叶森林栖息地的生物位移引起的生态地理隔离，增强了不同时空尺度以及冰期和间冰期期间黄色和紫色花谱系的分化。此外，限制基因流动的地质条件也可能是观察到的高遗传和地理分化的原因。嵌套进化枝分析（NCA）表明，异域破碎是造成所观察到的系统发育地理模式的主要因素，并且也支持历史变异因素的作用。因此，我们的结果支持了第四纪避难隔离促进了东亚温带植物异域物种形成的推论。这可能有助于解释东亚植物物种的高度多样性和特有性。
This study investigates the influence of climate-induced oscillations and complicated geological conditions on the evolutionary processes responsible for species formation in presently fragmented temperate forest habitats, located in continental East Asia. In addition to this, we also investigate the heavily debated issue of whether temperate forests migrated southwards during such glacial periods or, alternatively, whether there existed refugia within north China, enabling localized survival of temperate forests within this region. In order to achieve these, we surveyed the phylogeography of Bupleurum longiradiatum Turcz. (a herbaceous plant solely confined to temperate forests) constructed from sequence variation in three chloroplast (cp) DNA fragments: trnL–trnF, psbA–trnH and rps16. Our analyses show high genetic diversity within species (hT=0.948) and pronounced genetic differentiation among groups (yellow and purple flowers) with a significant phylogeographical pattern (NST>GST, P<0.05). Forty-three haplotypes were identified and clustered into two lineages (the purple-flowered lineage and the yellow-flowered lineage). Two corresponding refuge areas, one in Qinling and its adjacent regions and one in the Changbai Mountains/eastern China, were revealed across the entire distribution ranges of Bupleurum longiradiatum. These results provide evidence for the hypothesis that independent refugia were maintained across the range of temperate forests in northern China during the last glacial maximum or earlier cold periods. Bupleurum longiradiatum var. porphyranthum formed a single taxon based on molecular data. This specific formation process suggests that the historical vicariance factors, i.e. climate-induced eco-geographic isolation through the biotic displacement of temperate-deciduous forest habitats, enhanced the divergence of the yellow and purple flower lineages at different spatial–temporal scales and over glacial and interglacial periods. Additionally, geological conditions that restricted gene flow might also be responsible for the observed high genetic and geographic differentiation. A nested clade analysis (NCA) revealed that allopatric fragmentation was a major factor responsible for the phylogeographic pattern observed, and also supported a role for historical vicariance factors. Our results therefore support the inference that Quaternary refugial isolation promoted allopatric speciation of temperate plants in East Asia. This may help to explain the existence of high diversity and endemism of plant species in East Asia.