Xu Zhe, Zhang Ming-Li, Cohen James I
Key Laboratory of Biogeography and Bioresource in Arid Land, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, 830011, China.
State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China.
PLoS One. 2016 Sep 22;11(9):e0163243. doi: 10.1371/journal.pone.0163243. eCollection 2016.
In China, species of Atraphaxis (Polygonaceae) primarily inhabit arid zones across temperate steppe and desert regions. The complex geologic history (e.g., expansion of deserts) and extreme climate shifts of the region appear to have played an important role in shaping the phylogeography of Atraphaxis. The present study focuses on species-level phylogeographic patterns of Atraphaxis in China, with the goal of determining the impact of past environmental changes, in northern China, on the evolutionary history of the genus. Five hundred and sixty-four individuals distributed among 71 populations of 11 species of Atraphaxis from across the geographic range of the genus were studied using sequence data from two plastid spacers, psbK-psbI and psbB-psbH. The results demonstrate that most chloroplast haplotypes are species-specific, except for some present among widespread species. The phylogeny of Atraphaxis was well structured, and molecular dating analyses suggest that the main divergence events occurred during the late Pliocene and Pleistocene (5.73-0.03 million years ago). The statistical dispersal-vicariance analysis (S-DIVA) results provide evidence that phylogeographic patterns for the genus were characterized by both vicariance events and regional dispersal. The presented data suggest that the rapid expansion of deserts and climatic changes in northern China during the late Pliocene and Pleistocene have driven the diversification and spread of Atraphaxis in the region. The expansion of the Tengger Desert provided appropriate conditions for the origin of A. bracteata. Additionally, a contact zone in the north of the Hexi Corridor was identified as having played a significant role as a migratory route for species in adjacent areas.
在中国，木蓼属（蓼科）植物主要分布于温带草原和荒漠地区的干旱地带。该地区复杂的地质历史（如沙漠扩张）和极端的气候变化似乎在塑造木蓼属的系统地理学方面发挥了重要作用。本研究聚焦于中国木蓼属植物在物种水平上的系统地理格局，旨在确定中国北方过去的环境变化对该属植物进化历史的影响。利用来自两个叶绿体间隔区psbK - psbI和psbB - psbH的序列数据，对分布于木蓼属植物地理范围内11个物种的71个种群中的564个个体进行了研究。结果表明，除了一些广泛分布的物种中存在的单倍型外，大多数叶绿体单倍型是物种特异性的。木蓼属的系统发育结构良好，分子年代分析表明主要的分歧事件发生在上新世晚期和更新世（573万 - 3万年前）。统计扩散 - 隔离分析（S - DIVA）结果表明，该属的系统地理格局具有隔离事件和区域扩散的特征。现有数据表明，上新世晚期和更新世中国北方沙漠的快速扩张和气候变化推动了木蓼属植物在该地区的多样化和扩散。腾格里沙漠的扩张为苞叶木蓼的起源提供了适宜条件。此外，河西走廊北部的一个接触带被确定为在相邻地区物种的迁徙路线中发挥了重要作用。
