依据ITS rDNA序列探讨我国盾腹虫属种类的系统发育关系(英文)

PHYLOGENETIC RELATIONSHIP OF SPECIES IN THE GENUS ASPIDOGASTER (ASPIDOGASTRIDAE, ASPIDOGASTRINAE) IN CHINA AS INFERRED FROM ITS rDNA SEQUENCES

盾腹吸虫为寄生扁形动物中一小的类群。我国已报道7种盾腹吸虫,其中5种隶属于盾腹虫属(Aspidogastridae,Aspidogastrinae)。研究测定了在我国采集到的4种盾腹虫属吸虫的核糖体DNA转录内间隔区(ITSrDNA)序列,并分别采用邻接法和最大似然法构建分子系统发育树。结果显示,这4种盾腹吸虫的ITS-1和ITS-2序列的长度分别在728—877bp和518—645bp之间,其G+C含量分别在50.1%—52.3%和49.2%—52.2%范围内。4种盾腹吸虫的种间遗传距离在0.2%—26.9%之间,其中重庆盾腹吸虫(Aspidogaster chongqingensis)和似螺盾腹吸虫(A.limacoides)间仅为0.2%。所构建的最大似然树和邻接树具有相同的拓扑结构,均支持重庆盾腹吸虫和似螺盾腹吸虫亲缘关系最近,它们与饭岛盾腹吸虫(A.ijimai)亲缘关系较近,而与位于系统树基部的贝居盾腹吸虫(A.conchicola)关系较远。此外,对我国盾腹属种类的宿主特异性进行了讨论。

Five species in the genus Aspidogaster have been reported in China, and four species, i.e. A. conchicola Bare, 1827, A. limacoides Diesing, 1834, A. ijimai Kawamura, 1913 and A. chongqingensis Wei, Huang et Dai, 2001, were obtained to examine their phylogenetic relationship by comparing ITS rDNA sequences. The length of the ITS-1 and ITS-2 sequences ranged from 728 to 877 bp and 518 to 645 bp, and the G ＋ C content from 50.1 to 52.3% and 49.2 to 52.2%, respectively. Both maximum likelihood （ML） and neighbour-joining （NJ） phylogenetic trees revealed three well-supported main clades, which correspond respectively to A. limacoides and A. chongqingensis, A. ijimai, and A. conchicola, with A. conchicola located at the base of the phylogenetic tree. The group containing A. chongqingensis and A. limacoides formed the sister taxon to A. ijimai with 100% of bootstrap value. It was considered that A. chongqingen-sis and A. limacoides should be the closest, and they should be closer to A. ijimai than to A. conchicola. In addition, host specificity of Aspidogaster spp. in China was discussed.