The Evolutionary Pathways of Oxytropis Species of the Section Verticillares at the Center of the Section Origin

Abstract

Genetic diversity and phylogenetic relationships of Oxytropis species from the section Verticillares were studied on the basis of 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 Southern Siberia, Mongolia, and China). Moreover, for the first time, the reconstruction of phylogenetic relationships of species from the section Verticillares based on the analysis of ITS nrDNA has been performed. The article summarizes new material on the topic under study and data for a number of previously unstudied species and populations; 84.4% of 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 basis of ecological specialization; incomplete sorting of lineages with conservation of ancestral polymorphism in combination with hybridization of weakly diversified taxa; allopatric divergence and polyploidization. The analyses of chloroplast and nuclear genome markers indicate the rapid adaptive radiation of Oxytropis species from the section Verticillares.