确定促进物种形成的因素是生态和进化研究中的一项主要任务,可以通过系统地理学分析来帮助。位于中国中部的秦岭-大巴山脉(QDM)构成了南亚热带和北温带地区之间的重要地理屏障,表现出复杂的地形,气候,生态多样性。令人惊讶的是,很少对该地区的植物形态进行系统地理分析和研究。为了解决这个问题,我们调查了三个密切相关的牡丹物种的遗传差异和进化史(Paeoniaqui,P.jishanensis,和P.rockii)是QDM特有的。利用22个核简单序列重复标记(nSSRs)和3个叶绿体DNA序列对3种牡丹的40个种群进行基因分型,以评估遗传结构和系统发育关系,辅以形态表征和生态位建模(ENM)。形态和分子遗传分析表明,这三个物种之间有明显的区别。此外,使用DIYABC对nSSR变异进行的聚结分析表明,该物种在晚更新世相互分歧,而生态位建模(ENM)表明,它们在最后一次冰川最大(LGM)期间占据的面积比目前更大。来自细胞核和叶绿体DNA的综合遗传证据以及ENM的结果表明,每个物种在秦岭的多个避难所中都持续存在于晚更新世,Daba,和太行山的差异受到地理隔离导致的限制基因流动的青睐,生态分歧,和有限的花粉和种子传播。我们的研究有助于加深对牡丹的起源和种群结构的了解,并为中国中部秦岭-大巴山中存在的高水平植物特有性提供了见解。
Determining the factors promoting speciation is a major task in ecological and evolutionary research and can be aided by phylogeographic analysis. The Qinling-Daba Mountains (QDM) located in central
China form an important geographic barrier between southern subtropical and northern temperate regions, and exhibit complex topography, climatic, and ecological diversity. Surprisingly, few phylogeographic analyses and studies of plant speciation in this region have been conducted. To address this issue, we investigated the genetic divergence and evolutionary histories of three closely related tree peony species (Paeonia qiui, P. jishanensis, and P. rockii) endemic to the QDM. Forty populations of the three tree peony species were genotyped using 22 nuclear simple sequence repeat markers (nSSRs) and three chloroplast DNA sequences to assess genetic structure and phylogenetic relationships, supplemented by morphological characterization and ecological niche modeling (ENM). Morphological and molecular genetic analyses showed the three species to be clearly differentiated from each other. In addition, coalescent analyses using DIYABC conducted on nSSR variation indicated that the species diverged from each other in the late Pleistocene, while ecological niche modeling (ENM) suggested they occupied a larger area during the Last Glacial Maximum (LGM) than at present. The combined genetic evidence from nuclear and chloroplast DNA and the results of ENM indicate that each species persisted through the late Pleistocene in multiple refugia in the Qinling, Daba, and Taihang Mountains with divergence favored by restricted gene flow caused by geographic isolation, ecological divergence, and limited pollen and seed dispersal. Our study contributes to a growing understanding of the origin and population structure of tree peonies and provides insights into the high level of plant endemism present in the Qinling-Daba Mountains of Central
China.