We have conducted a phylogenetic analysis of 57 taxa including 127 accessions of Acer to determine the geographical origin and the presumptive progenitor species of Acer takesimense and A. okamotoanum, two endemics of the Korean island Ullung-do. Sequence analyses of the trnL intron and the trnL-trnF intergenic spacer of chloroplast DNA show a close relationship of A. takesimense to A. pseudosieboldianum from mainland Korea. Acer okamotoanum probably has evolved from Korean individuals of A. mono and not from Japan where A. mono is also native. AFLP data further support the proposed relationships and indicate a substantial loss of genetic diversity of A. takesimense when compared with the progenitor populations from mainland Korea. Both sequence and AFLP data put A. takesimense populations into a monophyletic group, suggesting that they speciated in Ullung Island from a single introduction from Korean peninsular populations. Populations of A. okamotoanum, on the other hand, show a higher degree of shared alleles with at least two mainland populations of their presumptive progenitor A. mono, perhaps indicating multiple origins of the latter endemic species.

Communicating Editor: Matt Lavin