Endemic Oxytropis Species of the Section Orobia (Fabaceae) from Asian Russia: Genetic Diversity and Demographic Dynamics

Nucleotide polymorphism of the psbA–trnH, trnL–trnF, and trnS–trnG intergenic spacers of chloroplast DNA was analyzed to assess the genetic diversity and demographic dynamics of endemic Oxytropis species of the section Orobia in two speciation centers, Southern Siberia and northeast Asia. Of the 34 studied populations of endemic species, five were monomorphic. These populations were found only in the species from northeast Asia. Eighteen populations (52.9%) were characterized by high haplotype diversity (h from 0.600 to 1.000), and 24 populations (70.6%) were characterized by low nucleotide diversity (π from 0.0001 to 0.0029). The reconstruction of demographic histories of 16 endemic populations showed that only four populations were characterized by bimodal mismatch distribution, corresponding to the demographic equilibrium model, while in all other populations, mismatch distribution was unimodal, corresponding to the population expansion model. Two populations of endemic species, O. leucantha subsp. tschukotcensis and O. popoviana (in Magadan oblast and Buryatia, respectively), with the high level of genetic diversity in a state of population stability were identified. These populations are probably located on the territory of ancient refugia and are of particular interest from the point of view of the species gene pool conservation.