我国赫坎按蚊复合体成员种的rDNA-ITS2区序列差异及系统发育分析

Anopheles hyrcanus complex from China:sequence differences of ribosomal DNA second internal transcribed spacer and phylogenetic analyses.

测定了我国赫坎按蚊复合体 9成员种的核糖体DNA第二内转录间隔区 (rDNA ITS2 )序列 ,根据序列差异分析各蚊种间的系统发育关系。结果显示 :( 1 )ITS2区序列最长的是中华按蚊 ( 4 6 8bp) ,最短的是克劳按蚊和赫坎按蚊 ( 4 36bp) ;GC含量为 4 4 9%～ 4 6 8% ;( 2 )发现该复合体 4成员种的ITS2区序列存在种内个体间差异 ,幅度为 0～ 3 8% ,明显小于种间差异 ;( 3)将各蚊种的ITS2区序列进行同源排序比较 ,发现其变异大多是简单重复单元的拷贝数不同 ;种间差异性最大的是克劳按蚊与嗜人按蚊( 32 3% ) ,最小的是贵阳按蚊与凉山按蚊 ( 9 0 % )平均差异率为 2 2 3% ;( 4 )根据ITS2区序列特征 ,用 3种方法构建的树状图拟合一致。以上结果表明赫坎按蚊复合体各成员种rDNA ITS2序列在种内非常保守 ,以种间序列差异分析为基础的分子鉴别技术是甄别蚊种分类地位混淆和错误的有效方法。

The ribosomal DNA second internal transcribed spacer of nine members in Anopheles hyrcanus complex from China was sequenced.The phylogenetic relationship was studied using sequence differences.The results were as follows: (1) The longest length of ITS2 region was 468 bp in An.sinensis , the shortest was 436 bp in An.crawfordi and An.hyrcanus .The level of GC content was from 44.9% to 46.8%.(2) The range of intraspecific differences in four members of this complex was from 0 to 3.8%, which was shorter than interspecific differences.(3) The ITS2 sequences alignment among nine members was made.The most variances were motif copy changes.The largest interspecific difference was 32.3% between An.crawfordi and An.anthropophagus , the shortest was 9.0% between An.kweiyangensis and An.liangshanensis , with the mean of 22.3%. (4) The phylogenetic trees which make using ITS2 character by three methods were the same.These represent that the intraspecific sequences of rDNA ITS2 in Anopheles hyrcanus complex were identical.The molecular identification using interspecific differences of rDNA ITS2 is effective method for discriminating the confusable spcecies and their taxonomic status.