Barkalov V. Yu., Kozyrenko M.M.
Botanicheskii zhurnal 2017; 102(1): 47-62
Analysis of variability of the nucleotide sequences of intergenic spacers of chloroplast DNA (the trnS-psbZ, the trnC-petN and the petN-psbM) in closely related species of the Salix aggr. berberifolia Pall. (S. berberifolia, S. fimbriata, S. kamtschatica, S. kimurana, S. vyshinii, S. tschuktschorum) revealed very low or no genetic differentiation. The level of nucleotide and gene diversity in the species populations varies within 0.000000-0.009722 and 0.000-1.000, respectively. Combinations of polymorphic sites form 14 haplotypes, of which 8 are unique. All studied species have a common haplotype; in addition common haplotypes occur in two or three species. Genetic distances between the species amounted to 0.001, except S. kimurana-S. tschuktschorum, S. kimurana-S. vyshinii, S. tschuktschorum-S. vyshinii, where they are zero. The low level of variability and the presence of common haplotypes indicate that these species present a genetically homogeneous group, formed probably as a result of a relatively recent and rapid divergence from a common ancestor, as well as a high degree of introgression hybridization (the reticulate evolution). The results indicate a relatively recent colonization of the Far Eastern part of the S. berberifolia s. l. range, probably in the Late Pleistocene. Weak morphological distinctions between S. aggr. berberifolia species may serve as an indirect evidence of the above. The complex of the «barberryleaved» willows can be conditionally subdivided into two closely related groups. The first group includes S. berberi- folia, S. fimbriata and S. kamtschatica, the second one - S. tschuktschorum, S. kimurana and S. vyshinii (the latter two are probably conspecific)
