The evolutionary pathways of <i>Oxytropis</i> species of the section <i>Verticillares</i> at the center of the section origin

Abstract

Genetic diversity and phylogenetic relationships of Oxytropis species from the section Verticillares were studied based on nucleotide polymorphism of cpDNA intergenic spacers psbA-trnH, trnL-trnF, and trnS-trnG at the center of the section origin (Baikal Siberia and adjacent territories of South Siberia, Mongolia, and China). Moreover, at the first time the reconstruction of phylogenetic relationships of species from section Verticillares based on the analysis of ITS nrDNA has been performed. The paper summarizes new samples and new data for unstudied species and populations. 84.4% populations of 11 species are characterized by a high level of chloroplast haplotype diversity (h varies from 0.700 to 1.000). The majority of populations (71.9%) have high haplotype diversity with low nucleotide diversity. Three haplogroups revealed in the genealogical network of chlorotypes indicate that there are different evolutionary pathways of the species included in these groups: divergence of genetically isolated taxa in the zone of sympatry presumably on the base of ecological specialization; incomplete lineage sorting with preserving of ancestral polymorphism in combination with hybridization of weakly diversified taxa; allopatric divergence and polyploidization. Analysis of markers of chloroplast and nuclear genomes testify the rapid adaptive radiation of Oxytropis section Verticillares.