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Many phylogeographic studies of various tree species have been conducted to elucidate the locations of refugia and the colonization patterns during the Pleistocene. However, only a few large-scale phylogeographic studies have been conducted on herbaceous plants, especially scarce on herbs that are adapted to disturbance. Artemisia indica is a fast-growing perennial herb found in open habitats. To examine the basic information on the genetic structure of this species, we investigated the chloroplast DNA variation within and among populations across Japan. We detected 26 haplotypes in 604 individuals from 28 Japanese populations. The haplotype A1 had wide geographic distribution, and its close relatives were locally present. Some putative ancestral lineages were found mainly in the Kyushu region. This may be because several lineages migrated from the Eurasian continent to the northern coast in Kyushu via the Korean peninsula during the Pleistocene, and the A1 haplotype expanded northward, whereas others remained in southern areas. Phylogenetic distant haplotypes were present mainly in the Kanto region. Because the geographic distribution pattern of these haplotypes in this region is believed to be unnatural, these haplotypes may be derived from commercial sources for re-vegetation during the last few decades. [ABSTRACT FROM PUBLISHER]

Miscanthus sinensis Andersson is a dominant perennial grass in East Asia, where it is a pioneer species in disturbed habitats. To obtain basic information about the genetic structure of this pioneer species, we investigated chloroplast DNA (cpDNA) variation in M. sinensis within and among native populations across Japan. We detected nine haplotypes in 636 individuals from 30 populations. Two distinct haplotypes had a wide geographical distribution and coexisted within most of the populations. The degree of genetic differentiation among the populations was relatively low. Two putative ancestral lineages were distributed in the Ryukyu Islands. Therefore, it is possible that lineages that originated in subtropical areas of mainland China migrated into the Ryukyu Islands via Taiwan. Another possible migration route is the Korean Peninsula. Two major haplotypes may have migrated from the Eurasian continent to the northern coast in Kyushu via the Korean Peninsula and then expanded throughout Japan. There was no clear genetic boundary among the populations north of Kyushu. The enhanced immigration ability and high rate of gene flow of Miscanthus may have modulated the genetic structure created during previous glacial periods. Alternatively, the shortage of unique haplotypes north of Kyushu may indicate the recent expansion of this species to northern Japan. [ABSTRACT FROM AUTHOR]