ORIGIN OF PARTHENOGENETIC POPULATIONS AND THEIR PHYLOGENETIC RELATIONSHIPS IN APHIDS

蚜虫通常从春天到秋天以孤雌生殖的方式繁殖，有很多无性世代，在秋天有一次有性繁殖。然而，完全孤雌生殖的生命周期已经从这种典型的生命周期衍生了许多次。本研究通过对线粒体COI-COII区的测序，确定了完全无性种群的Colopha属有性种群和无性种群之间的遗传分化程度以及有性种群和无性种群之间的系统发育关系。Kansugei Colopa kansugei是一种完全孤雌生殖的物种，广泛分布于日本西部、琉球群岛、中国南部、泰国北部和尼泊尔。寄主植物的生物地理和化石记录表明，自主要寄主植物灭绝约数百万年后，该物种继续进行孤雌生殖。线粒体COI-COII区的比较表明，该物种种群间的遗传分化水平很高。FO…更多的例子是，在大约1200个碱基对的DNA序列中，Tateyama和Fukuoka群体之间存在8个位点的差异，并且这种差异对于种内分化来说是非常高的。因此，分子证据证实了甘肃华支睾吸虫长期持续孤雌生殖的假说。长期以来，甘肃华支睾吸虫与卡尔滕巴克氏菌和四射线虫之间的系统发育关系一直悬而未决。根据线粒体COI-COII区构建的分子系统发育分析表明，Colopa首先从其他分类群中分出分支，Kaltenbachiella和Tetraneura形成姐妹分类群。这一结果与榆属寄主植物的分布和古生物学证据相一致。Colopa与榆属类群联系在一起，具有分离分布，而Tetraneura和Kaltenbchiella与榆属类群联系在一起，具有广泛和连续的分布。因此，分子信息有助于解决形态信息无法处理的系统发育问题。较少

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 … More 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