Jamshed Shayan, Kim Joo-Hwan
Department of Life Sciences, Gachon University, Seongnam, South Korea.
Front Plant Sci. 2022 Mar 11;13:825209. doi: 10.3389/fpls.2022.825209. eCollection 2022.
Scientists have long been captivated by biogeographic disjunctions, and disjunctions between East Asia and North America have been particularly well-studied at the genus and family levels. By contrast, disjunctions between eastern and western Asia have received less attention. L. is taxonomically divided into two sections based on the number of cells in anthers as follows: . sect. has one-celled anthers and occurs mainly in Asia, whereas . sect. has two-celled anthers and is distributed globally. We used Illumina sequencing to investigate the genomes of four species in sect. . The chloroplast (cp) genomes are highly conserved (157,290-158,094 bp). Pseudogenisation of F and intron loss in 16 was detected. Based on the cp genomes of the four species of . sect. , we propose a novel hypothesis of disjunction between eastern and western Asia. Biogeographic reconstruction and molecular dating revealed that sect. separated from its sect. forebears 4.0 Mya during the Pliocene era. The radial diversification of sect. from East Asia and the establishment of the western Asian clade during the Pleistocene era (1.9 Mya) were the results of both dispersal and vicariance, making the section the youngest diverged clade conforming to age estimation. The centre of origin of sect. was determined to be in East Asia. Disjunctions and diversification between eastern and western Asia in sect. are thought to have been caused by changes in monsoon patterns, temperature variations, and the emergence of the Gobi Desert.
长期以来，科学家们一直对生物地理间断现象很感兴趣，东亚和北美之间的间断现象在属和科的层面上得到了特别深入的研究。相比之下，东亚和西亚之间的间断现象受到的关注较少。L. 根据花药中的细胞数量在分类学上分为两个组，如下所示：……组……有单室花药，主要分布在亚洲，而……组……有双室花药，分布于全球。我们使用Illumina测序技术对……组中的四个物种的基因组进行了研究。叶绿体（cp）基因组高度保守（157,290 - 158,094碱基对）。检测到F的假基因化和16中内含子的丢失。基于……组四个物种的cp基因组，我们提出了一个关于东亚和西亚之间间断现象的新假说。生物地理重建和分子定年显示，……组在中新世时期4.0百万年前与其……组祖先分离。……组在更新世时期（1.9百万年前）从东亚的辐射状多样化以及西亚分支的建立是扩散和隔离分化的结果，这使得该组成为符合年龄估计的最年轻分化分支。……组的起源中心被确定为在东亚。……组中东亚和西亚之间的间断现象和多样化被认为是由季风模式变化、温度变化以及戈壁沙漠的出现所导致的。
