5种寄生蚌螨COI基因片段序列及系统发育分析

采用PCR技术对5种寄生蚌螨COI基因片段进行序列测定.序列分析的结果表明,比对后的序列总长度均为658 bp;其中A、G、C、T 4种碱基的平均含量分别为34.6%、20.2%、14.3%、30.9%,平均嘧啶含量（65.5%）明显高于嘌呤含量（34.5%）,说明碱基存在偏向性.弯弓蚌螨Unionicola arcuata与Y纹蚌螨U.ypsilophora 的种间遗传差异为26.4%,达到属间分类水平,结果支持Vidrine将沃蚌螨亚属从寄蚌螨亚属中分离的修订;螫爪蚌螨U.chelata与敏捷蚌螨U.agilex之间遗传差异为23.3%,达到属间分类水平,结果支持文春根等将敏捷蚌螨与其姊妹种腰蚌螨U.lumbaria放入韦蚌螨亚属中的修订.以营自由生活的厚蚌螨U.crassipes作为外类群,使用PAUP4.0b 10软件中的最大似然法（ML）和邻接法（NJ）构建系统树,结果显示：在5种寄生蚌螨中敏捷蚌螨可能是最早从祖先种分化出来的种;弯弓蚌螨与Y纹蚌螨可能起源于蚌螨属的同一个祖先.

Sequence and Phylogeny Analysis of Mitochondrial CO I Gene Obtained from Five Species Unionicolid Mites

A nucleotide sequence analysis of mitochondrial cytochrome coxidase subunit I （CO I） gene fragment was conducted among five species unionicolid mites. The results of sequence comparisons showed that the aligned nucleotide fragments is 658 bp in length. Accordingly, the percentages of A＋T and G＋C are 65.5% and 34.5% in the nucleotide sequence, showing a strong AT bias. 26.4% genetic divergences between Unionicola arcuata and U. ypsilophora, there supported Vidrine＇ s revision for the subgenus Parasitatax that Wolcottatax was divorced from the subgenus Parasitatax;23.3% genetic divergences between U. chelata and U. agilex, there supported Wen et al. the revised for the subgenus Vidrinatax that two sibling species （U. agilex and U. lumbaria） added in the subgenus Vidrinatax. Using U. crassipes as outgroup, the phylogenetic trees were reconstructed with NJ and ML inferences （PAUP 4.0b10 tool）,and the results showed that U. agilex might be the first separated from ancestral species;U, arcuata and U. ypsilophora might stem from the same ancestors.