Genetic differentiation of the three species of genus Astragalus L. of section Cenantrum Bunge (Fabaceae)

Genetic differentiation based on allozyme data was detected between species of the genus Astragalus L., section Cenantrum Bunge (Fabaceae): A. frigidus (L.) A. Gray s. l., A. mongholicus Bunge s. 1., and A. sericeocanus Gontsch, which is endemic to the northeast coast of Lake Baikal. The results of allozyme analysis confirm the natural division of the section into subsections based on morphological features. Differences between A. frigidus (subsection Elliptica Gontsch.) and A. mongholicus and A. sericeocanus (subsection Semilunaria Gontsch.) were observed. These differences were caused by the presence of species-specific alleles and the allele frequencies of the primary alleles, D N = 1.24. The genetic distance obtained for A. mongholicus and A. sericeocanus (0.10) corresponds to the status of closely related species of one subsection. Between populations of A. frigidus and between populations of A. mongholicus from the central part of areal, D N = 0.02 and 0.03 respectively. This genetic distance corresponds to the interpopulation level and was determined by the allele frequencies. The peripheral population of A. mongholicus is separated (D N = 0.36), which is probably due to the long isolation and the “founder effect.”