A comprehensive study on the adaptive radiation and biodiversity of the Drosophila virilis section

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The Drosophila virilis section was studied from an evolutionary point of vies of adaptive radiation and biodiversity in green belts of East Asia. Most species of the virilis section living in the temperate region repeated generation alternation several times per year, and the females did not develop their ovaries from mid September and entered reproductive diapause for hibernation. Any species belonging to the large quadrisetata species group has not been known for seasonal changes of natural populations, and it is first known that Drosophila quadrisetata spends two generations per year. The virilis section flies used cliff-shelters covered by roots of trees or ferns along stream as hibernation sites. Drosophilaokadai of the robusta group characteristically spent a single generation per year.Several species were maintained under various photoperiodic conditions from the egg stage and studied for the development of ovaries. Reproductive diapause was induced under short daylength in Dros … More ophila okadai, a uni-voltine species, and this has showed that diapause of Drosophila okadai is facultative and a single generation per year is due to the limited period suitable for the life of Drosophila okadai.On the other hand, ovarian development proceeded without any delay even under short photoperiodic regimes in Drosophila daruma, a tropic or subtropical member of the polychaeta species groupLocal populations of Drosophila tsigana, a member of the melanica species group, showed remarkable morphological variations for the band patters on the abdominal tergites. The warm temperate form collected from Tokyo and Kyoto possessed entirely black tergites of males but the cool temperate one from central Hokkaido did black caudal bands interrupted largely at middle on tergites II to IV. Any discriminative character on the male genitalia was not been detected between these two forms.Reproductive isolation was studied by no-choice method, and incomplete isolation was detected between the two forms of Drosophila tsigana. A mitochondrial gene of COI was analyzed, and the gene sequences were compared among local populations of Drosophila tsigana. The molecular phylogenic tree showed that the warm temperate form of Japanese Drosophila tsigana was situated near to Chinese Drosophila tsigana collected from Guizhou, rather than the cool temperate form of Japanese Drosophila tsigana. Less