Phylogeography Of Pomatosace Filicula

How Quaternary climatic oscillations affected range distributions and intra-specific divergence of alpine plants on the Qinghai-Tibetan Plateau (QTP) remains largely unknown. Here we report a survey of chloroplast DNA (cpDNA) and nuclear ribosomal internal transcribed spacer (ITS) DNA variation aimed at exploring the phylogeographical history of the QTP endemic herb, Pomatosace filicula Maxim. We amplified and sequenced two cpDNA fragments (psbA-trnH and matK) and also the nuclear (ITS) region in200individuals from24populations sampled throughout the species’range, and a series of conventional analyses was employed to interpret data collected. The results shows that there are7chlorotypes in this species, and these chlorotypes were clustered into three lineages; distribution ranges of chlorotypes were highly overlapped with each other, and populations with high chlorotype diversity occur in both plateau platform and plateau edge; AMOVA showed that cpDNA genetic diversity were distributed evenly both within populations and among populations (FSt=0.560); PERMUT simulations detect no significant phylogeographic structure (P>0.05); Mismatch distribution suggest a stable population for individuals bear all chlorotypes, but a population expansion for individuals bear chlorotypes in lineage I, which comprising5chlorotypes; neutral test suggest that this species may have experience bottleneck or founder effect events. Meanwhile, there are two nuclear ITS genotypes occur in the northern and southern range of this species. BEAST age estimations revealed that divergence between nuclear ITS genotypes occurred0.54Mya (million years agao); and divergences among the three chloroplast lineages occurred1.39-0.92Mya, while lineage Ⅰ started to diversify since0.49Mya. All available evidences suggest that, the Quaternary climate oscillations is the main driving force that underlie the intra-specific divergence of Pomatosace filicula; and this species may have experienced complex populations dynamic history, e.g. repeated range expansion and contraction; and this herb may have survived at multiple glacial refugia both in the plateau platform and plateau eage areas.