中文摘要：

该研究基于直翅目56 种昆虫的COI基因全序列构建了该目部分类群间的系统发育关系, 同时也分析了COI基因编码的氨基酸序列构建直翅目系统发育关系的可靠性。将COI序列按照密码子一、二、三位点划分, 分别计算PBS（partioned Bremer support）值, 评估蛋白质编码基因密码子不同位点的系统发生信号强度。分析结果支持螽亚目和蝗亚目的单系性; 剑角蝗科、斑腿蝗科、斑翅蝗科、网翅蝗科和槌角蝗科5 科均不是单系群, 科间的遗传距离在0.107-0.153之间变化, 与其他科相比遗传距离较小, 符合将这5 科合并为一科（即蝗科）的分类系统,瘤锥蝗科和锥头蝗科归为锥头蝗总科, 癞蝗科单独成为一科, 这也与Otte（1997）系统的划分一致。根据PBS值的大小推断密码子第三、第一位点对系统树分支的贡献比第二位点大, 并且较长的序列含有较多的信息位点。研究也证实将各物种COI基因之间的遗传距离作为直翅目划分科级阶元的工具是可行的。

英文摘要：

Complete sequences of the COI gene were used to reconstruct the phylogenetic relationship among 56 species from Orthoptera. We also analyzed the reliability of Orthoptera phylogenetic relationship using translated amino acid sequences of the COI genes. The COI sequences were divided into three data sets on the basis of different codon positions to calculate the Partitioned Bremer support （PBS）, and to test the phylogenetic signal in different codon positions of protein-coding genes. The result supports the monophyly of Caelifera and Ensifera; but the monophyly of Acrididae, Catantopidae, Oedipodidae, Arcypteridae and Gomphoceridae are not supported. The P-distances among families vary from 0.107 to 0.153, which are smaller than those of other families, being consist with the classification that these 5 families should be merged into one family （Acrididae）. Chrotogonidae and Pyrgomorphidae belong to the superfamily Pyrgomorphoidea. Pamphagidae should be a family alone consistent with Otte’s taxonomic system. According to the PBS values, the 3rd and 1st codon positions contribution more for the Phylogenetic tree branches than the 2nd, and longer sequences contain more informative sites. We further demonstrated that it is feasible for phylogenetic studies at family level to use the genetic distances among COI sequences from different species of Orthopera.