Genetic diversity of the Rhododendron subsection Ledum species in Sakhalin Island: data from chloroplast DNA markers variability

A high genetic variability was revealed in the populations of the Rhododendron subsection Ledum species complex in Sakhalin. In total, 94 individuals from natural populations of the four sympatric species of Labrador tea (R. tomentosum, R. subarcticum, R. tolmachevii and R. hypoleucum) were analyzed to evaluate the genetic variation in the territory of the Sakhalin Island and in two mainland populations. The haplotype diversity of five chloroplast intergenic spacers (trnH–psbA, petB–petD, 3’trnV (UAC)–ndhC, K2R–K707, atpB–rbcL) was quite high. There were 16 haplotypes (h1–h16) identified; h1, h2 and h4 are the most common, the rest were rare and no species-specific ones were found. Analysis of Molecular Variance (AMOVA) indicate that about 37 % of the genetic diversity is due to among population differences (FST = 0.37, p < 0.001). Molecular phylogenetic analysis based on chloroplast DNA data did not reveal a clear species structure, but revealed a trend towards the isolation of two genetic groups: including a group of samples from the southern and the middle parts of Sakhalin Island.