Morphological and Genetic Differentiation of Populations of Rhododendron aureum Georgi. (Ericaceae) in the Mountains of Southern Siberia and on the Kamchatka Peninsula

A study of morphological traits in the populations of R. aureum from Western and Eastern Sayan and Kamchatka has been carried out. The variability of genetic nuclear DNA microsatellite markers (nSSRs) has been studied in the same samples. A total of 15 absolute and relative morphological traits of shoots and leaves, as well as 18 polymorphic microsatellite markers in eight natural populations of R. aureum, are observed. It is found that the following parameters are the most variable within species populations: plant size, shoot length, length of the foliated part of shoots, and number of leaves relative to shoot length; relative leaf shape parameters are more stable parameters. The reliable division of populations into three geographical groups on all set of morphological characters is established. One important taxonomic character, the leaf life span, is shown to make a great contribution on the shoot to the division of geographical groups of populations and individual populations. The structure of morphological differentiation of populations is confirmed by the results of the analysis of genetic variability of the same populations of R.aureum by nuclear microsatellite markers. The greatest genetic distances from other populations are established for the Kamchatka populations. There is a tendency toward the differentiation of populations within the Altai-Sayan mountain country. The results of the study agree well with the information on geography, ecology, and biology of the species. The study of intra- and interpopulation morphological differentiation of R. aureum populations in Siberia is conducted for the first time, following the recently initiated studies on genetic variability of the species in Northern Eurasia.