| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2002: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2001: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 2000: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Research Abstract |
Aphids typically reproduce parthenogenetically from spring to autumn with many asexual generations, and reproduce sexually once in autumn. However, wholly parthenogenetic life cycles have derived many times from this typical life cycle. This study determined the extent of genetic differentiation between sexual and asexual populations and phylogenetic relationships between sexual and asexual species in the genus Colopha with wholly asexual species, by sequencing the mitochondrial COI-COII region. Colopha kansugei is a wholly parthenogenetic species with a broad distribution in western Japan, the Ryukyu Islands, southern China, northern Thailand and Nepal. Biogeographical and fossil records of the host plants suggest that this species has continued parthenogenetic reproduction since the extinction of the primary host plants for about a few million years. Comparisons of mitochondrial COI-COII region indicated a high level of genetic differentiation between populations for this species. Fo
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r example, there was a difference of 8 sites in a DNA sequence of about 1200 base pairs between the Tateyama and Fukuoka populations, and this difference is exceptionally high for intraspesific differentiation. Therefore, molecular evidence confirms the hypothesis that C. kansugei has continued parthenogenetic reproduction for a long time.
The phylogenetic relationships between Colopha, Kaltenbachiella and Tetraneura have been unsolved for a long time. Molecular phylogenies constructed based on the mitochondrial COI-COII region indicated that Colopha has first branched off the other taxa, and that Kaltenbachiella and Tetraneura form a sister taxon. This result is consistent well with the distributional and paleobiological evidence of the host plants, the genus Ulmus. Colopha is associated with a Ulmus group with disjunctive distribution, while Tetraneura and Kaltenbachiella are associated with a Ulmus group with a extensive and continuous distribution. Thus, molecular information was useful for solving the phylogenetic problem which morphological information was not able to deal with. Less
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