Phylogeography of alpine plant Parnassia wightiana (Celastraceae)

Abstract

Parnassia wightiana Wall. ex Wight & Arn., a perennial herb, is an alpine plant distributed across three biodiversity hotspots in China. This species offers an excellent study system to analyze the distribution pattern and genetic structure of high mountainous plant populations. Three chloroplast DNA (cpDNA) regions ( rpl32- t rnL, trnL-F, and trnS-G) from 442 individuals of 39 populations and internal transcribed spacers (ITS) from 418 individuals of 38 populations were sequenced and analyzed. We identified a total of 26 haplotypes based on the concatenated sequences of cpDNA and a total of 36 based on ITS sequences. A hierarchical analysis of molecular variance indicated significant phylogeographic structure among populations. Mismatch analysis of multipeak and Tajima’s D neutral test demonstrated Parnassia wightiana populations within China had not experienced abrupt expansion recently. The allopatric fragmentation resulted in the geographic isolation due to environmental heterogeneity, producing a high proportion of private haplotypes in the distribution of Parnassia wightiana within China.