Molecular phylogenetic and biogeographical analysis of Nitraria based on nuclear and chloroplast DNA sequences

Based upon DNA sequences from six plastid regions (rbcL, psbB-psbH, trnL-trnF, rpS16, psbA-trnH, rpS16-trnK) and the internal transcribed spacer (ITS) region of nuclear ribosomal DNA, the phylogenetic relationships in the genus Nitraria and family Nitrariaceae are investigated by using methods of maximum parsimony, maximum likelihood, and Bayesian inference. Our study strongly supports the monophyly of Nitraria. Nitraria can be divided into four parts, namely, the N. sphaerocarpa group, N. retusa group, the N. roborowskii and N. tangutorum group, and a group consisting of N. schoberi, N. komarovii, N. sibirica, and N. billardieri. Ancestral area reconstruction using S-Diva shows that eastern Central Asia is most likely the place of origin, and then dispersals occurred to western Central Asia, Africa, and Australia.