Year: 2025, Number: 3, Pages: 16-38
Phylogenetic relationships within the section Orobia, the largest section of the genus Oxytropis (Fabaceae), are investigated using molecular methods. Original data on plastid genome variability in 42 species and subspecies from this section, distributed across the Asian part of Russia, are summarized. Analysis of nucleotide polymorphism in the cpDNA intergenic spacers psbA-trnH, trnL-trnF, and trnS-trnG from 617 plants revealed 237 haplotypes, of which 12 were shared by multiple taxa. The median network of haplotype genealogical relationships comprises a complex of eight star-like structures, where neighboring haplotypes are linked by 1–2 mutational steps. The observed polytomy in phylogenetic trees and the pattern of haplotype genealogical connections are consistent with the hypothesis of “explosive” speciation, indicating an almost simultaneous divergence of many phylogenetic lineages from a common ancestor followed by rapid morphological radiation to the species level. Consequently, species within the section Orobia form a single genetic pool despite exhibiting clear morphological diff erences. During subsequent diversifi cation, statistically supported clades emerged, occupying terminal positions in the genealogical network; notably, a single well-defi ned phyletic lineage formed by O. maydelliana haplotypes. The data refute the hypothesis of conspecifi city between O. sordida and O. maydelliana. However, relationships among most taxa remain unresolved, suggesting that further phylogenetic studies of the section Orobia should be continued, including the application of cytological methods.