Phylogeography of Japanese alpine plants: biogeographic importance of alpine region of Central Honshu in Japan

A preliminary synthesis of the geographic distribution patterns of intraspecific cpDNA variations in Japanese alpine plants is presented by studying five species, namely, Pedicularis chamissonis, Primula cuneifolia, Loiseleuria procumbens, Cardamine nipponica, and Anemone narcissiflora. Nucleotide sequences of the noncoding regions of cpDNA recognized multiple cpDNA haplotypes in these species. Phylogenetic analyses of these haplotypes suggest two or three major cpDNA clades; each clade has a clearly disjunct distribution pattern in the northern parts of Japan, and in the central parts of Japan. The southernmost clades endemic to central Honshu in Japan were found in all the species (Central Honshu clade). We estimate that the major clades of Pedicularis chamissonis and Primula cuneifolia separated from a common ancestor before the last glacial period (>0.6 and 0.47 million years ago, respectively). We speculate that the common distribution patterns of the cpDNA clades observed in central Honshu were formed by dynamic climatic changes (e.g., glacial events in the Pleistocene) and that the alpine regions of central Honshu acted as refugia for alpine plants during warm interglacial periods.