Genomic Phylogeography of Gymnocarpos przewalskii (Caryophyllaceae): Insights into Habitat Fragmentation in Arid Northwestern China

Extensive range of deserts and gobis (rocks) had promoted habitat fragmentation of species in arid northwestern China. Distribution of endangered Gymnocarpos przewalskii Maxim. covers most of gobis (rocks) and desert terrain across arid regions of northwestern China. In the present study, we had employed genomic phylogeographical analysis to investigate population structure of G. przewalskii and test the effect of environmental conditions on spatial pattern of genetic diversity. Results showed four groups were identified from east to west: Edge of the Alxa Desert, Hexi Corridor, Hami Basin, and North edge of the Tarim Basin. Genetic diversity was at an equal level among four groups. General linear model (GLM) analysis showed spatial pattern of genetic diversity was significant correlated with three habitat variables including habitat suitability at present (Npre) and last glacial maximum (LGM) (NLGM) periods, and locality habitat stability (NStab). It concluded that habitat fragmentation had triggered lineage divergences of G. przewalskii in response to long-term aridification. Genome-wide single nucleotide polymorphisms (SNPs) could increase the ability of clarifying population structures in comparison with traditional molecular markers. Spatial pattern of genetic diversity was determined by fragmented habitats with high habitat suitability (Npre and NLGM) and stability (NStab). At last, we propose to establish four conservation units which are in consistent with the population grouping to maintain the genetic integrity of this endangered species.

Phylogeography of the rare Gymnocarpos przewalskii (Caryophyllaceae): indications of multiple glacial refugia in north-western China

We investigated the phylogeography of Gymnocarpos przewalskii Maxim. (Caryophyllaceae), a rare relictual shrub restricted to north-western China, in the context of Quaternary climate oscillations. Three cpDNA regions (psbA–trnH, ycf6–psbM and rpl32–trnL (UAG)) were sequenced for 160 individuals from 16 populations. High genetic diversity (hT = 0.930, hS = 0.425) and a significant phylogeographic structure (NST > GST, P < 0.01) were identified; 31 different cpDNA haplotypes were detected. Phylogenetic analyses showed that the haplotypes were clustered into five clades, consistent with their distributions in the following four geographic regions: the Tarim Basin, Hami Basin, the western Yumen of Gansu Province and an easternmost region, consisting of populations in the Wulate Rear Banner region in Inner Mongolia, the Jinta and Jingyuan regions in Gansu Province and the Zhongwei region in Ningxia. The existence of regional divergence was supported by AMOVA, which revealed that ~63% of variation was due to differences among the four geographic regions. Four independent glacial refugia were inferred, in the western Tarim Basin, Hami Basin, the Liuyuan region in western Gansu and the easternmost region mentioned. Population bottlenecks and postglacial recolonisation were identified in the northern Tarim Basin, western Yumen and the Jinta region in Gansu Province.