Molecular Phylogenetic Analysis of the Endemic Far Eastern Closely RelatedOxytropis Species of Section Orobia (Fabaceae)
There are still unresolved questions about the taxonomic status and phylogenetic relationships of far eastern closely related species Oxytropis ochotensis, O. litoralis, O. erecta, O. ruthenica and O. kunashiriensis of section Orobia of the genus Oxytropis. The study of the nucleotide sequence polymorphism of the psbA–trnH, trnL–trnF and trnS–trnG cpDNA intergenic spacers showed that populations of O. ochotensis and O. erecta are characterized by a low (0.378–0.495) haplotype and a low (0.0006–0.0009) nucleotide diversity, and in populations of O. ruthenicah varies from 0.154 to 0.872, π – from 0.0002 to 0.0016. One O. ochotensis population from the Magadan region and one O. ruthenica population from the Russky Island (Primorsky Krai) are monomorphic. Low nucleotide divergence of cpDNA between O. ochotensis, O. erecta and O. litoralis species, as well as statistically insignificant genetic differentiation between them, the formation of single haplogroup in the phylogenetic network and the absence of species-specific molecular markers indicate the unity of their gene pool. A study of the ITS rDNA polymorphism revealed private ribotypes in O. ruthenica and O. kunashiriensis, the presence of a common ribotype in O. ochotensis, O. erecta and O. litoralis, and the intraspecific polymorphism in O. ochotensis and O. erecta. The differences revealed in the chloroplast and nuclear genomes confirm the independence of O. ruthenica and O. kunashiriensis, and suggest that O. erecta and O. litoralis are local phenotypes of the widespread polyploid species O. ochotensis. An analysis of the phylogenetic relationships of the cpDNA haplotypes showed a clear separation of O. ruthenica populations into two evolutionary lineages, but with a single ITS ribotype.