Patterns of Genetic Variation in Swertia przewalskii, an Endangered Endemic Species of the Qinghai-Tibet Plateau

Abstract

Swertia przewalskii Pissjauk. (Gentianaceae) is a critically endangered and endemic plant of the Qinghai-Tibet Plateau in China. RAPD and ISSR analyses were carried out on a total of 63 individuals to assess the extent of genetic variation in the remaining three populations. Percentage of polymorphic bands was 94% (156 bands) for RAPD and 96% (222 bands) for ISSR. A pairwise distance measure calculated from the RAPD and ISSR data was used as input for analysis of molecular variance (AMOVA). AMOVA indicated that a high proportion of the total genetic variation (52% for RAPD and 56% for ISSR) was found among populations; pairwise Phi (ST) comparisons showed that the three populations examined were significantly different (p < 0.001). Significant genetic differentiation was found based on different measures (AMOVA and Hickory theta(B)) in S. przewalskii (0.52 on RAPD and 0.56 on ISSR; 0.46 on RAPD and 0.45 on ISSR). The differentiation of the populations corresponded to low average gene flow (0.28 based on RAPD and 0.31 based on ISSR), whereas genetic distance-based clustering and coalescent-based assignment analyses revealed significant genetic isolation among populations. Our results indicate that genetic diversity is independent of population size. We conclude that although sexual reproduction and gene flow between populations of S. przewalskii are very limited, they have preserved high levels of genetic diversity. The main factors responsible for the high level of difference among populations are the isolation and recent fragmentation under human disturbance.

Phylogeographic structure of Terminalia franchetii (Combretaceae) in southwest China and its implications for drainage geological history

“…This region harbours about 12,000 species of vascular plants, of which at least 20 genera and 3,500 species are endemic (Myers et al 2000;Wang and Zhang 1994;Wilson 1992;Wu 1988;Ying et al 1993). Previous studies of plant phylogeography in this region have focused mainly on taxa from the plateau areas of the Qinghai-Tibetan Plateau and adjacent mountain ranges (e.g., the Hengduan Mountains) (Yuan et al 2008;Zhang et al 2007aZhang et al , 2005. However, from a phylogeographic perspective, far less attention has been devoted to the endemic flora of the valleys of the region, e.g.…”

Genetic diversity in Nepalese population of Swertia chirayita (Roxb. Ex Fleming) H. Karst based on inter-simple sequence repeats (ISSR) markers

“…However, RAPD based analysis of 34 accessions of S. chirayita (used in this present research) revealed 92.28% polymorphism (Shrestha et al, 2013). S. tetraptera, an endemic species of Qinghai-Tibetan Plateau revealed 98.9% polymorphism using ISSR fingerprinting and S. przewalskii from the same region showed 56% polymorphism using ISSR marker (Zhang et al, 2007). Genetic polymorphism shown with ISSR analysis for Neopicrorhiza scrophulariiflora also showed high level of polymorphism of 100% (Liu et al, 2011), likewise, 100% for Dendrobium studies (Wang et al, 2009).…”

“…(13 of S. chirayita and 2 each of Swertia cordata, Swertia paniculata and Swertia purpurascenes) collected from the temperate Himalayas of India (Joshi and Dhawan, 2007). In the investigation of endangered endemic species, Swertia przewalskii of the Qinghai-Tibet plateau using RAPD and ISSR analysis, Zhang et al (2007) observed the significant genetic differentiation based on different measures including analysis of molecular variance (AMOVA) (52% for RAPD and 56% for ISSR). Misra et al (2010) used amplified fragment length polymorphism (AFLP) to produce DNA fingerprints for Swertia spp.…”

Genetic diversity and historical demography of the narrow-range endemic Alpine toad, Scutiger liupanensis, in the Liupan Mountains of central China

“…Some studies have found lower levels of genetic diversity in species with smaller ranges than their more widespread sibling species, due to genetic drift, bottlenecks, isolation, inbreeding, low levels of gene flow, and directional selection that promotes adaptation to the local environment (Hamrick and Godt, 1989;Hamrick et al, 1992;Torres-Diaz et al, 2007;Gibson et al, 2008). However, other studies have found that species with small ranges possess moderate to high levels of genetic variation (Gitzendanner and Soltis, 2000;Zhang et al, 2007;Crema et al, 2009), but very few narrowly endemic animals have been included in similar analyses.…”