蝽科部分昆虫细胞色素b基因序列及其系统发育关系的探讨

以线粒体细胞色素b(Cyt b)基因作为分子标记，对蝽科蝽亚科3种、益蝽亚科2种、荔蝽亚科1种、盾蝽亚科2种昆虫进行序列测定，获得Cyt b基因432bp的序列片段，该片段中碱基T、C、A、G的平均含量分别为31．3％、12．4％、37．6％和18．7％，A T平均含量为68．9％，明显高于G C含量(30．1％)；密码子第三位点A T含量更高达82．7％。属和种间序列变异大，碱基替换多发生在第三位点。以筛豆龟蝽(Megacopta cribraria)为外群构建系统发育树，结合形态特征与序列变异率，赞同将盾蝽亚科、荔蝽亚科从蝽科划分出来并提升为科的观点，它们之间的系统关系为：盾蝽科与荔蝽科形成姊妹群，较蝽科发育得早；蝽科作为一个单系群，是蝽总科中最为进化的类群。

Discussion on the Phylogenetic Relationships of Partial Pentatomidae Insects Based on Sequences of Cytochrome b Gene

This paper dealt with the nucleotide composition and the phylogenetic relationship among 8 species in Pentatomidae (Pentatominae,Asopinae,Tessaratominae,Scutellerinae) based on 432bp sequences of Cyt b gene.The results showed:the average contents of T,C,A and G are 31.3%,12.4%,37.6% and 18.7%,respectively;the contents of A T (68.9%) is obviously higher than that of C G (30.1%),and come up to 82.7% at the third position of codon.The divergence of sequences is higher among genera and species,and replacement of nucleotides mostly occurs at the third position.The bug,Megacopta cribraria regarded as outgroup,the phylogenetic tree is set based on molecular information.Altogether with morphology characters,it is very reasonable that the two subfamily,Tessaratominae and Scutellerinae should be separated from family Pentatomidae,and be two valid families.The phylogenetic relationship of them is shown as follow:Tessaratomidae and Scutelleridae constitute a sister group and diverge more early than Pentatonidae;as a monophyletic clade,Pentatomidae is the most evolutionary group in Pentatomoidea.