吉陶单极虫地理分布新记录及不同地理株系间的比较

为获知吉陶单极虫不同地理株系间的遗传变异及系统发育关系,实验对吉陶单极虫中国重庆、中国湖北、中国四川、日本盐田、韩国全北、韩国首尔等地理株系进行形态学比较及基于18S rDNA序列的变异位点、相似度、遗传距离、基因型的比较和系统发育分析.结果 发现,吉陶单极虫各株系孢子形态特征基本一致;18S rDNA序列相似度为99...

New record of geographic distribution of Thelohanellus kitauei and its comparative study of different geographic strains

[Purposes] To clarify the genetic variation and phylogenetic relationships among different geographic strains of Thelohanellus kitauei. [Methods] Comparative analyses were conducted on strains of T. kitauei from Chongqing of China, Hubei of China, Shioda of Japan, Jeonbuk of Korea and Seoul of Korea based on their morphology. The comparison and analyses were also conducted for their site variation, similarity, genetic distance, genotype and phylogeny based on 18S rDNA sequences. [Findings] The morphological characteristics of strains of T. kitauei from different localities were generally consistent. Among different strains, the similarities were 99.5%~100.0%, variation sites were 0~6, genetic distances were 0.000~0.004, based on 18S rDNA sequences. The phylogenetic analysis showed that thelohanellids with membrane sheath clustered as a clade and the remaining thelohanellids without membrane sheath clustered as another clade. The clade without membrane sheath divided into fin-infection group and gill-infection group. [Conclusions] The membrane sheath should not use as a valid feature for species identification of T. kitauei whose identification should still be according to its morphology and morphometry of the spore excluding membrane sheath. Though the shape and size of membrane sheath was unstable, its present and absence on thelohanellid might associate with phylogeny of Thelohanellus. And the evolution pattern for clade possessing membrane sheath might be different from the clade without membrane sheath. The strains of T. kitauei did not form special divergences in different parasitic sites and also did not form monophylies in different localities. The reason for this genetic situation might be: the isolation time was not long enough or the high frequence of gene flow among different strains which lead a limited population divergence.