Abstract
BackgroundIncarvillea sinensis is widely distributed from Southwest China to Northeast China and in the Russian Far East. The distribution of this species was thought to be influenced by the uplift of the Qinghai-Tibet Plateau and Quaternary glaciation. To reveal the imprints of geological events on the spatial genetic structure of Incarvillea sinensis, we examined two cpDNA segments ( trnH- psbA and trnS- trnfM) in 705 individuals from 47 localities.ResultsA total of 16 haplotypes was identified, and significant genetic differentiation was revealed (GST =0.843, NST = 0.975, P < 0.05). The survey detected two highly divergent cpDNA lineages connected by a deep gap with allopatric distributions: the southern lineage with higher genetic diversity and differentiation in the eastern Qinghai-Tibet Plateau, and the northern lineage in the region outside the Qinghai-Tibet Plateau. The divergence between these two lineages was estimated at 4.4 MYA. A correlation between the genetic and the geographic distances indicates that genetic drift was more influential than gene flow in the northern clade with lower diversity and divergence. However, a scenario of regional equilibrium between gene flow and drift was shown for the southern clade. The feature of spatial distribution of the genetic diversity of the southern lineage possibly indicated that allopatric fragmentation was dominant in the collections from the eastern Qinghai-Tibet Plateau.ConclusionsThe results revealed that the uplift of the Qinghai-Tibet Plateau likely resulted in the significant divergence between the lineage in the eastern Qinghai-Tibet Plateau and the other one outside this area. The diverse niches in the eastern Qinghai-Tibet Plateau created a wide spectrum of habitats to accumulate and accommodate new mutations. The features of genetic diversity of populations outside the eastern Qinghai-Tibet Plateau seemed to reveal the imprints of extinction during the Glacial and the interglacial and postglacial recolonization. Our study is a typical case of the significance of the uplift of the Qinghai-Tibet Plateau and the Quaternary Glacial in spatial genetic structure of eastern Asian plants, and sheds new light on the evolution of biodiversity in the Qinghai-Tibet Plateau at the intraspecies level.
Highlights
Incarvillea sinensis is widely distributed from Southwest China to Northeast China and in the Russian Far East
We concentrated on elucidating the spatial genetic structure of an attractive herb, Incarvillea sinensis Lam., which is widely distributed from the southwest China through to the northeast China and the Russian Far East (Figure 1), whose biogeographic history was proposed to be closely related to the uplift of the Qinghai-Tibet Plateau and to Quaternary climate oscillations [34]
After investigating all of the specimens of Incarvillea sinensis in CDBI, E, K, KUN, PE, and SZ, and exploring its distribution in China, we found that its variation in morphology was regional and that all populations can be classified into three types (Figure 1, Table 1)
Summary
The distribution of this species was thought to be influenced by the uplift of the Qinghai-Tibet Plateau and Quaternary glaciation. We concentrated on elucidating the spatial genetic structure of an attractive herb, Incarvillea sinensis Lam., which is widely distributed from the southwest China through to the northeast China and the Russian Far East (Figure 1), whose biogeographic history was proposed to be closely related to the uplift of the Qinghai-Tibet Plateau and to Quaternary climate oscillations [34]. The former is an annual herb with simple roots, while the latter is a perennial herb with woody, branched roots and often bears the remains of the previous year’s stems In another system described in Flora Reipublicae Popularis Sinicae [36], two variants were recognized, I. sinensis var. The distribution was split due to the occurrence of perennial groups with yellow and red flowers in the middle of the entire species distribution
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