Potential refugium on the Qinghai–Tibet Plateau revealed by the chloroplast DNA phylogeography of the alpine species Metagentiana striata (Gentianaceae)

Abstract

Metagentiana striata is an alpine annual herbaceous plant endemic to the east of the Qinghai-Tibet (Q-T) Plateau and adjacent areas. The phylogeography of M. striata was studied by sequencing the chloroplast DNA (cpDNA) trnS-trnG intergenic spacer. Ten haplotypes were identified from an investigation of 232 individuals of M. striata from 14 populations covering the entire geographical range of this species. The level of differentiation amongst populations was very high (GST = 0.746; NST = 0.774) and a significant phylogeographical structure was observed (P < 0.05). An analysis of molecular variance found a high variation amongst populations (76%), with FST = 0.762 (highly significant, P < 0.001), indicating that little gene flow occurred amongst the different regions; this was explained by the isolation of populations by high mountains along the Q-T Plateau and adjacent areas (Nm = 0.156). Only one ancestral haplotype (A) was common and widespread throughout the distributional range of M. striata. The populations of the Hengduan Mountains region of the south-eastern Q-T Plateau showed high diversity and uniqueness of haplotypes. It is suggested that this region was the potential refugium of M. striata during the Quaternary glaciation, and that interglacial and postglacial range expansion occurred from this refugium. This scenario was in good agreement with the results of nested clade analysis, which inferred that the current spatial distribution of cpDNA haplotypes and populations resulted from range expansion, together with past allopatric fragmentation events.

Range shifts of Potentilla fruticosa on the Qinghai-Tibetan Plateau during glacial and interglacial periods revealed by chloroplast DNA sequence variation

“…This conclusion is supported by the unimodal mismatch distribution of the northeastern populations (Figure 4a), suggesting historical population expansion, and by the star-shaped phylogeny of haplotypes derived from haplotype A (Figure 2), the reduced levels of haplotypic and nucleotide diversity (Table 1), and the prevalence of haplotype A in the northeastern populations (Figure 1). The homogeneous genetic pattern in the northeastern populations is consistent with the AMOVA result, which showed relatively low genetic variation among populations (48.7%) in comparison with other alpine plant species on the Plateau (Chen et al, 2008;Yang et al, 2008;Wang et al, 2009). These patterns are consistent with the results of a simulation study in which sudden expansion from a few populations produced reduced allele diversity and areas of genetic homogeneity (Avise, 2000).…”

“…Wang et al (2009) suggested that Aconitum gymnandrum has survived on high-altitude parts of the central Plateau throughout the Quaternary. In contrast, Metagentiana striata and Pedicularis longiflora probably expanded from refugia on the eastern edge to the central Plateau during the interglacial and postglacial periods (Chen et al, 2008;Yang et al, 2008). Therefore, these three investigated alpine species do not share a common phylogeographical history.…”

“…Recent phylogeographic studies have examined the demographic history of alpine plants across the Plateau (Chen et al, 2008;Yang et al, 2008;Wang et al, 2009). Wang et al (2009) suggested that Aconitum gymnandrum has survived on high-altitude parts of the central Plateau throughout the Quaternary.…”

Dispersals of Hyoscyameae and Mandragoreae (Solanaceae) from the New World to Eurasia in the early Miocene and their biogeographic diversification within Eurasia

“…The recent range expansion from the 'hot spot' of the mountains of the southeastern TP has been observed in other plants and birds at the population level. Examples include Juniperus przewalskii (Cupressaceae) , Metagentiana striata (Gentianaceae) (Chen et al, 2008), Pedicularis longiflora (Orobanchaceae) (Yang et al, 2008), Picea crassifolia (Pinaceae) (Meng et al, 2007), and the red-necked snow finch Pyrgilauda ruficollis (Qu et al, 2005). Phylogeographic studies on these species show that populations from the wide range of the platform are dominated by one or a few haplotypes and are mostly nested within diverse haplotypes from the southeastern mountains of the TP.…”

Genetic consequences of postglacial colonization by the endemic Yarkand hare (Lepus yarkandensis) of the arid Tarim Basin

“…In contrast, studies on the Asian biota have been rather limited. The complex topography of East Asia probably provided refugia for species during times of Pleistocene glaciation [14], yet only a few plant and bird species restricted to the Qinghai-Tibetan Plateau (QTP) have been evaluated [15][16][17][18][19][20].…”