Phedimus takesimensis (Ulleungdo flat-leaved stonecrop) is endemic to Ulleung and Dokdo Islands off the east coast of the Korean Peninsula. It was suggested that P. takesimensis originated via anagenetic speciation from the continental progenitor species P. kamtchaticus or P. aizoon. However, little is known of the phylogenetic relationships and population genetic structure among species of Phedimus in the Korean Peninsula and Ulleung/Dokdo Islands. We inferred the phylogenetic relationships among congeneric species in Korea based on nuclear ribosomal DNA internal transcribed spacer and chloroplast noncoding regions. We also sampled extensively for P. takesimensis on Ulleung Island and the continental species, P. kamtschaticus and P. aizoon, to assess the genetic consequences of anagenetic speciation. We found (1) the monophyly of P. takesimensis, (2) no apparent reduction in genetic diversity in anagenetically derived P. takesimensis compared to the continental progenitor species, (3) apparent population genetic structuring of P. takesimensis, and (4) two separate colonization events for the origin of the Dokdo Island population. This study contributes to our understanding of the genetic consequences of anagenetic speciation on Ulleung Island.

The complete chloroplast genome sequence of Phedimus kamtschaticus , which commonly occurs in northeastern Asia was determined. The genome size was 151,652 bp, composed of one pair of inverted repeats (IRs) of 25,977 bp, which were separated by one large single-copy (LSC; 83,010 bp) and one small single-copy (SSC; 16,688 bp) region. The chloroplast genome contained 132 genes, including 88 protein-coding genes, 36 tRNA genes, and 8 rRNA genes. The overall GC content was 37.8%. Phylogenetic analysis of the complete chloroplast genome suggested that P. kamtschaticus was most closely related to Ulleung Island insular endemic P. takesimensis .