Mechanisms for speciation and breeding system in plant species accompanied with phylogeographic structure.

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Phylogeographic structures within a plant taxon would imply intraspecific differentiation in genetics, morphologies, reproduction, physiological and/or ecological traits, of which provide good arena for speciation and evolution. In this project, we elucidated phylogeographic structures in plant taxa on high mountains and continental island systems, the Ryukyu Islands, by determining cpDMA haplotypes or Karyomorphology. The distribution of cpDNA haplotypes in three alpine plants (Phyllodoce nipponica, Potentilla matsumurae and Diapensia nipponica) was geographically highly structured, and an abrupt genetic changes were detected between mountains in central Houshu and the Tohoku region. Haplotypes in central Honshu were thought to have diverged, suggesting that mountains in central Honshu served as refugia during the Quaternary climatic oscillations. Moreover, intraspecific variation of chromosome number and cytogeography were examined for samples of Lysimachia mauritiana from the Ryukyu Islands. This plants on the Ryukyu Islands harbor wide range of variation, ranging from 2n=16(6m), 2n=17(6m), 2n=17(7m), 2n=18(4m), 2n=18(5m), 2n=18(6n), 2n=19(5m), 2n=20(2m) to 2n=20(4m). Large islands with high altitude (e.g., Amamioshima Island and Tokunoshima Island) harbor the wider variation, suggesting these islands could act as refugia during the inter- and/or post- glacial transgression in the Quaternary climatic oscillations. On the other hand, islands with lower altitude harbor simple structure in cytotype, which would be attributable to bottleneck effects during the warm periods.