Abstract: The topological effect of the Qinghai-Tibetan Plateau during the Quaternary climatic oscillation must have important effects on spatial distribution and genetic structure of organisms distributed there. At the same time, the ecological niches provided by the uplifts of the plateau and the following Quaternary climatic changes may have promoted morphological differentiation and speciation of plants occurring there. The plateau endemic Hippophae neurocarpa (Elaeagnaceae) is a dominant shrub species along the streams or rivers and it also occurs in the semi-arid ecosystem. This species is recognized as two separate subspecies, i.e. ssp. neurocarpa and ssp. stellatopilosa, mainly according to the appendages on leaves and different habitat preferences. The former is characteristic of scale-like appendages on the leaves and distributed in the drier and colder habitats while the latter has stellate hairs with a preference of occurring in the wetter and warmer habitats. It is interesting to know whether the morphological sub-speciation of H. neurocarpa is correlated with the intra-specific chloroplast phylogeny. In addition, this species also provide a good proxy to test the hypothesis that a few cold- or dry-tolerating species survive in the high altitude region of the plateau during the Quaternary glacial stages. In this study, we examined chloroplast trnL-F sequence variation from both subspecies of H. neurocarpa. The chloroplast genome was found to be maternally inherited in Hippophae and the intraspecific genealogy may reflect the maternal lineage sorting between both subspecies. A total of eight haplotypes were recovered through sequencing 70 individuals from 14 populations. One was shared by both subspecies, and four and three were only found in ssp. neurocarpa and ssp. stellatopilosa respectively. These findings suggested that two subspecies did not show genealogical concordance with morphological differentiation in this fragment. The constructed nested cladogram classified eight haplotypes into three lineages: one consisted of endemic haplotypes of ssp. neurocarpa and the other two included haplotypes from both subspecies with those of ssp. neurocarpa at the tip positions. In addition, the unique haplotypes recov-ered in the high altitude suggested that this species might have survived in these arid habitats. The contiguous range expansion was detected from these different refugia.

Key words: contiguous range expansion, cpDNA, Hippophae neurocarpa, phylogeography, Qinghai-Tibetan Plateau, refugia, sub-speciation, trnL-F