Изменчивость ядерного маркера RPB2 у видов багульников Евразии и Северной Америки

An unambiguous delimitation of Ledum species (genus Rhododendron, subgenus Rhododendron, subsection Ledum) has not yet been established. In the present study, we genetically analyzed 89 specimens of five species of the subsection Ledum from Eurasia and North America, based on the variability of a nuclear DNA marker, an intron fragment between the second and the third exons of the RPB2 gene. A high level of interpopulational polymorphism (FST = 0.8514, p < 0.001) was revealed by the marker under research, while the degree of intersprecies differentiation was lower (FCT = 0.42, p < 0.001). The phylogenetic analysis showed that all the studied Ledum samples form a monophyletic clade that had separated from other rhododendrons about 34 Mya, which corresponds to the beginning of the Oligocene cooling. No clear division into species is observed within the Ledum clade. The clades with R. groenlandicum specimens from North America and R. subarcticum (Chukotka, Kamchatka, central Sakhalin) are highly supported. The remaining species in Eurasia (R. tomentosum, R. hypoleucum, R. diversipilosum) are weakly differentiated on a genetiс basis.