Search

Abstract: Inter-simple sequence repeat markers (ISSR) were used to estimate genetic diversity within and among 10 populations of Rhodiola chrysanthemifolia along Nianqingtangula Mountains and Brahmaputra, a species endemic to the Qinghai-Tibet Plateau and an endangered medicinal plant. Of the 100 primers screened, 13 produced highly polymorphic DNA fragments. Using these primers, 116 discernible DNA fragments were generated of which 104 (89.7%) were polymorphic, indicating substantial genetic diversity at the species level. Genetic diversity measured by the percentage of polymorphic bands (PPB) at the population level ranged from 21.97% to 48.8%. Analysis of molecular variance (AMOVA) showed that the genetic variation was found mainly among populations (77.3%), but no regional differentiation was discernible. Variance within populations was only 22.7%. The main factor responsible for this high level of differentiation among populations is probably the historical geographical and genetic isolation of populations in a harsh mountainous environment. Concerning the management of R. chrysanthemifolia, the high genetic differentiation of populations indicates the necessity of conserving the maximum possible number of populations. [Copyright &y& Elsevier]

Abstract: To clarify the relationship between two genera, Draba and the narrow genus Coelonema, endemic to the QilianMountains of the northeastern Qinghai-Tibet Plateau, phylogenetic analyses were conducted using nuclear ribosomal DNA ITS, and the chloroplast DNA trnL, from Coelonema draboides and 30 species of Draba representing eight sections, including 25 species of Chinese Draba, seven of which were endemic to the study region. The results unambiguously support several previously published proposals to unite Coelonema with Draba and accommodate C. draboides in the latter genus on the basis of morphological re-examination. Our molecular data presented here also provide evidence that these two genera should be combined as a monophyletic group with high support. In addition, it is estimated that Draba may have originated about 1.36–2.71 Mya, with C. draboides diverging from Draba about 0.15–0.31 Mya, based on the molecular calibration of ITS datasets. The assumed speciation and rapid expansion of these two genera is likely to have occurred in the eastern edge of the QilianMountains area according to molecular phylogeny and estimated divergence times, which correspond well with the known geological and paleobotanical histories of the Qinghai-Tibet Plateau. [ABSTRACT FROM AUTHOR]

The Qinghai-Tibetan plateau (QTP) uplift had a decisive effect on climatic and eco-environmental evolution in East Asia during the Quaternary. In the current study phylogeographic structure and diversification history of Spiraea alpina across the QTP were investigated for the first time based on nuclear internal transcribed spacer. The nuclear internal transcribed spacers ( ITS 1a –ITS 4 ) were generated for a total of 284 individuals distributed within 31 natural populations. A clear phylogeographic structure was found for S. alpina . The results showed that this species colonized in three different glacial refugia during the Quaternary extensive glaciation and expanded during the Interglacial period. Analysis of molecular variance (AMOVA) showed 74.13% genetic diversity among populations and 25.87% genetic variation within populations with distinct phylogeographic structure ( F ST = 0.741*). The estimated divergence time revealed that the main lineages of S. alpina diversified during the Quaternary 1.2–0.6 million years ago. The study concluded that severe climatic oscillations during Quaternary and the uplift of QTP had a profound effect on intraspecific divergence of S. alpina . [ABSTRACT FROM AUTHOR]