Germplasm Bank of Wild Species in Southwest China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, Yunnan, China.
Natural History Research Centre of Shanghai Natural History Museum, Shanghai Science & Technology Museum, Shanghai, 200041, China.
Sci Rep. 2021 Feb 18;11(1):4147. doi: 10.1038/s41598-021-83473-w.
In East Asia, genetic divergence is usually considered to be correlated to different floristic regions, however, subtropical-tropical divergence is largely ignored, compared to widely explored temperate-subtropical divergence. Lindera aggregata (Lauraceae), a dominant species in South-East China was selected to address this issue. Fifteen low-copy nuclear genes (LCGs) and four chloroplast DNA (cpDNA) fragments were used to detect its evolutionary history. In LCGs, STRUCTURE and dated Bayesian phylogeny analyses detect distinct subtropical-tropical divergence since late Pleistocene. Approximate Bayesian calculation (ABC) further supports the distinct subtropical-tropical divergence, and close related Taiwan and South China populations are diverged at the last interglacial. Isolation by distance, isolation by environment and isolation by resistance analyses suggest the current climatic difference rather than geographical distance contributes to the genetic differentiation. Principle component analysis shows populations of tropical cluster occur in warmer area with higher precipitation. Ancestral area reconstruction based on Bayesian phylogeny indicates that ancestral L. aggregata populations are distributed in tropical region. In cpDNA, although unique haplotypes are found in tropical region, distinct subtropical-tropical divergence is absent. In conclusion, distinct late Pleistocene subtropical-tropical divergence of L. aggregata is triggered by climate. It is likely that L. aggregata is originated in Southwest-South China and experienced hierarchical dispersal from south to north. The South China Sea land bridge has dual role in connecting or isolating Taiwan and mainland populations since the last glaciation.
在东亚，遗传分化通常被认为与不同的植物区系有关，但与广泛研究的温带-亚热带分化相比，亚热带-热带分化在很大程度上被忽视了。本研究选择了中国东南部的优势种黄肉楠（樟科）来解决这个问题。本研究使用了 15 个低拷贝核基因（LCGs）和 4 个叶绿体 DNA（cpDNA）片段来检测其进化历史。在 LCGs 中，STRUCTURE 和基于贝叶斯的系统发育分析检测到晚更新世以来明显的亚热带-热带分化。近似贝叶斯计算（ABC）进一步支持了明显的亚热带-热带分化，并且密切相关的台湾和华南种群在末次间冰期就已经分化。距离隔离、环境隔离和抗性隔离分析表明，当前的气候差异而不是地理距离导致了遗传分化。主成分分析表明热带集群的种群出现在温暖地区，降水较高。基于贝叶斯系统发育的祖先区重建表明，黄肉楠的祖先种群分布在热带地区。在 cpDNA 中，尽管在热带地区发现了独特的单倍型，但不存在明显的亚热带-热带分化。综上所述，黄肉楠明显的晚更新世亚热带-热带分化是由气候引起的。黄肉楠可能起源于中国西南-华南地区，并经历了从南到北的分层扩散。末次冰期以来，南海陆桥在连接或隔离台湾和大陆种群方面发挥着双重作用。
