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Central Asia, especially the Tian‐Shan and Pamir‐Alay, is a biodiversity hotspot for Hedysarum (Fabaceae) with a high number of endemic species. However, to date, studies of the genus Hedysarum based on molecular data have included only a few species distributed in this region. To fill this gap, we analysed 110 Hedysarum species, 36 of which were from the Tian‐Shan and Pamir‐Alay Mountains of Central Asia. We performed phylogenetic analyses, divergence time estimates, and biogeographic analyses using both the internal transcribed spacers of nuclear ribosomal DNA (nrDNA ITS) and three plastid DNA (cpDNA) sequences (trnL‐trnF, matK, psbA‐trnH). Our phylogenetic analysis grouped the species of Hedysarum into three sections: H. sect. Hedysarum, sect. Multicaulia, and sect. Stracheya, which are largely consistent with previous phylogenetic classifications. Accordingly, most of the Central Asian species we studied (28 spp.) were placed in H. subsect. Crinifera within H. sect. Multicaulia. Our divergence time and biogeographic analyses indicate that Hedysarum likely originated in West Asia and/or East Asia during the Early Miocene or Middle Miocene and subsequently dispersed to adjacent areas of Eurasia, as well as North America via the Bering Land Bridge. The likely area of origin for H. sect. Multicaulia is West Asia, while East Asia appears to be the center of origin for H. sect. Hedysarum and sect. Stracheya. In addition, we suggest that the rapid radiation of the species of H. subsect. Crinifera occurred in the Tian‐Shan and Pamir‐Alay Mountains, as well as the Turkish‐Iranian Plateau, and that geological and climatic changes were the main causes of speciation in Hedysarum. [ABSTRACT FROM AUTHOR]

The flora of northern China forms the main part of the Sino‐Japanese floristic region and is located in a south–north vegetative transect in East Asia. Phylogeographic studies have demonstrated that an arid belt in this region has promoted divergence of plants in East Asia. However, little is known about how plants that are restricted to the arid belt of flora in northern China respond to climatic oscillation and environmental change. Here, we used genomic‐level data of Myripnois dioica across its distribution as a representative of northern China flora to reconstruct plant demographic history, examine local adaptation related to environmental disequilibrium, and investigate the factors related to effective population size change. Our results indicate M. dioica originated from the northern area and expanded to the southern area, with the Taihang Mountains serving as a physical barrier promoting population divergence. Genome‐wide evidence found strong correlation between genomic variation and environmental factors, specifically signatures associated with local adaptation to drought stress in heterogeneous environments. Multiple linear regression analyses revealed joint effects of population age, mean temperature of coldest quarter, and precipitation of wettest month on effective population size (Ne). Our current study uses M. dioica as a case for providing new insights into the evolutionary history and local adaptation of northern China flora and provides qualitative strategies for plant conservation. [ABSTRACT FROM AUTHOR]

Aim: East Asia exhibits complex geomorphological and climatic characteristics. The aim of this study was to test whether the so‐called three‐step landforms of China, together with the East China Sea (ECS), have acted to shape specific phylogeographical patterns and affected the biogeographical history of the species belonging to the East Asian Flora. Location: China and Japan. Taxon: Kerria japonica (L.) DC. Methods: Three chloroplast DNA regions and 15 nuclear microsatellite (nSSR) loci were sequenced and genotyped in 576/450 individuals of K. japonica. Phylogeographical analyses were performed to assess the genetic structure, historical gene flow and demographical history of these individuals, and climatic factors were examined to determine their effects on phylogeographical breaks. Furthermore, time‐calibrated phylogenetic trees and ancestral range reconstruction were used to infer the biogeographical history of K. japonica. Potential habitats at present and during the last glacial maximum (LGM) were identified using ecological niche modelling. Results: Distinct phylogeographical breaks were found across the ECS and along the boundary of the three‐step landforms of China. Low historical gene flow and significant climatic differences were detected in each pair of adjacent regions. The results of molecular dating and ancestral range reconstruction indicated that K. japonica originated in North America during the mid‐Miocene (14.76 Ma), and intra‐specific diversification began in the late Miocene (7.78 Ma). Compared to the relatively stable distribution range of Chinese populations, Japanese populations experienced range expansion after the LGM in response to Quaternary climate change. Main conclusions: Kerria japonica has a complex biogeographical history, with a mid‐Miocene origin in North America and subsequent migration into East Asia via the Bering land bridge. The onset of intra‐specific diversification was probably associated with Asian monsoon intensifications, while exposure to the ECS floor facilitated the formation of the Japanese lineage in the late Miocene. The spatiotemporal population differentiation on the Chinese mainland demonstrates the significant role of biogeographical divides delineated by the three‐step landforms of China and provides clues to understand the floristic regionalization and evolutionary history of plant diversity in East Asia, especially with respect to the Hengduan Mountains, Central China and East China. [ABSTRACT FROM AUTHOR]

[Display omitted] • The "ampliative" Spiraea japonica complex was put forward. • Phylogeographical pattern is related to the regionalization of East Asian flora. • Genetic and diterpenoid alkaloids data support a transition belt in central China. • Diversification and demographic dynamics were shaped by the geological events. • Polyploidization contributed to the population expansion in east China. 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. [ABSTRACT FROM AUTHOR]

The East Asian endemic genus Rodgersia comprises five species and several variants. These species exhibit variation in ploidy level and a fragmented distribution across the whole of East Asia. In order to explain their present distribution pattern under a robust phylogeny, we employed multiple copy nuclear genes (ITS and ETS), cpDNA ( rpl 32- trn L, trn V- ndh C, ndh F- rpl 32) and a low copy nuclear gene (GBSSI) to reconstruct the species’ relationships within Rodgersia . Identification of ploidy levels was also carried out for most of samples. The early-diverging positions of R. nepalensis and R. podophylla were confirmed in different gene trees. Much topological incongruence among gene trees was found in the shallower branches, which comprised the species of central-southwest China. Both incomplete lineage sorting and ancient introgression may be responsible for the incongruent pattern observed. Ancient introgressions may have occurred between diploid species and the diploid progenitors of tetraploid species in different areas of southwest China. Rodgersia probably originated in Northeast Asia during the Pliocene. This genus is a rare example in which two early-diverging species occur at opposite ends of the distribution area, likely resulting from successive vicariance events. Unlike many vicariance events shaped simply by forest fragmentation during the Pleistocene, the contemporary biogeographic pattern of Rodgersia is more the result of rapid sympatric evolution (reticulate events and polyploidization) of the taxa in the central area. [ABSTRACT FROM AUTHOR]

Searsia is an Old World genus in the sumac family Anacardiaceae segregated from the Rhus complex. The genus is widely distributed in Africa with three species in eastern Asia, of which Searsia paniculata was commonly recognized as Terminthia paniculata in China. In this study, we conducted phylogenetic analyses of the eastern Asian Searsia to test the relationships to the African relatives, based on both nuclear (ETS and ITS) and chloroplast ( trnL – F and ndhF ) sequences. Phylogenetic analyses based on different genomic sequences strongly support that the Searsia taxa from eastern Asia are monophyletic. However, topological incongruence is observed between the nuclear and chloroplast data, especially concerning the phylogenetic position of the eastern Asian group. The divergence time of the genus between eastern Asia and Africa was dated to 23.36 Ma (million years ago), with a 95% highest posterior density (HPD) of 14.30–36.31 Ma, using the Bayesian relaxed-clock estimation. It is hypothesized that the closure of the Tethys Sea and the formation of the “ Gomphotherium Landbridge” likely had enabled the expansion of the Searsia lineage between Africa and Asia in the late Oligocene to early Miocene. [ABSTRACT FROM AUTHOR]