Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, 132 Lanhei Road, Kunming 650201, China.
College of Forestry, Southwest Forestry University, Kunming 650224, China.
Mol Phylogenet Evol. 2023 Jul;184:107772. doi: 10.1016/j.ympev.2023.107772. Epub 2023 Mar 26.
Each subkingdom of East Asian flora (EAF) has a unique evolutionary history, but which has rarely been described based on phylogeographic studies of EAF species. The Spiraea japonica L. complex, which is widespread in East Asia (EA), has received considerable attention because of the presence of diterpenoid alkaloids (DAs). It provides a proxy for understanding the genetic diversity and DA distribution patterns of species under various environmental conditions associated with the geological background in EA. In the present study, the plastome and chloroplast/nuclear DNA of 71 populations belonging to the S. japonica complex and its congeners were sequenced, combined with DA identification, environmental analyses, and ecological niche modelling, to investigate their phylogenetic relationships, genetic and DAs distribution patterns, biogeography, and demographic dynamics. An "ampliative" S. japonica complex was put forward, comprising all species of Sect. Calospira Ser. Japonicae, of which three evolutionary units carrying their respective unique types of DAs were identified and associated with the regionalization of EAF (referring to the Hengduan Mountains, central China, and east China). Moreover, a transition belt in central China with its biogeographic significance was revealed by genetic and DA distribution patterns from the perspective of ecological adaptation. The origin and onset differentiation of the "ampliative" S. japonica complex was estimated in the early Miocene (22.01/19.44 Ma). The formation of Japanese populations (6.75 Ma) was facilitated by the land bridge, which subsequently had a fairly stable demographic history. The populations in east China have undergone a founder effect after the Last Glacial Maximum, which may have been promoted by the expansion potential of polyploidization. Overall, the in-situ origin and diversification of the "ampliative" S. japonica complex since the early Miocene is a vertical section of the formation and development of modern EAF and was shaped by the geological history of each subkingdom.
东亚植物区系（EAF）的每个亚区都有独特的进化历史，但很少基于 EAF 物种的系统地理学研究来描述。在东亚广泛分布的绣线菊属（Spiraea japonica L.）复合体由于含有二萜生物碱（DAs）而受到广泛关注。它为了解与东亚地质背景相关的各种环境条件下物种的遗传多样性和 DA 分布模式提供了一个代理。本研究对 71 个绣线菊属复合体及其近缘种的质体和叶绿体/核 DNA 进行了测序，结合 DA 鉴定、环境分析和生态位模型，研究了它们的系统发育关系、遗传和 DAs 分布模式、生物地理学和种群动态。提出了一个“扩增”的绣线菊属复合体，包含了所有的 Calospira 节、Ser. Japonicae 系列，其中鉴定出三个携带各自独特类型 DAs 的进化单元，与东亚植物区系的区域化（指横断山区、中国中部和华东地区）有关。此外，从生态适应的角度揭示了遗传和 DA 分布模式所反映的中国中部过渡带及其生物地理学意义。“扩增”的绣线菊属复合体的起源和起始分化估计发生在中新世早期（22.01/19.44 Ma）。陆桥促进了日本种群（6.75 Ma）的形成，随后其种群历史相对稳定。末次冰期后，中国东部的种群经历了奠基者效应，这可能是多倍体化扩张潜力的推动。总体而言，自中新世早期以来“扩增”的绣线菊属复合体的原地起源和多样化是现代东亚植物区系形成和发展的垂直剖面，由每个亚区的地质历史塑造。
