Phylogeography of the Korean pine (Pinus koraiensis) in northeast Asia: inferences from organelle gene sequences.

Range-wide genetic variation of Korean pine (Pinus koraiensis) was assessed using maternally inherited mtDNA and paternally inherited cpDNA for 16 natural populations throughout northeast Asia in order to study its phylogeographical history during the Quaternary. The cpDNA variation indicated that there was no difference between populations on the Asian continent and those in the Japanese archipelago. In contrast, the mtDNA variation indicated that there was significant difference between the populations from the two regions, with each region having a different lineage. The continental populations exhibited no diversity in the mtDNA examined despite the species' current extensive range and large populations. Conversely, while the Korean pine is rare in Japan, the Japanese populations exhibited greater levels of mtDNA diversity (H (T) = 0.502). The higher mtDNA diversity and evidence from numerous Korean pine macrofossil remains dated to the Pleistocene and recovered various sites in Japan suggest that the Japanese archipelago once served as a refugium to a much larger Korean pine population with a more extensive range than is the case today. The presence of the single mtDNA haplotype across the Asian continent suggests that the present widespread populations could have expanded from a single refugium population after the last glacial periods.