基于28SrDNA的叩甲科分子系统发育关系研究

Molecular phylogenetic analysis of Elateridae(Insecta:Coleoptera)based on 28S rDNA gene fragments

【目的】通过对叩甲科（Elateridae）昆虫核糖体28SrDNA基因片段序列进行比较，从分子水平研究叩甲科昆虫的系统发育关系，并和传统分类结果相比较，为我罔叩甲科分类系统的论证和进一步修订奠定基础。【方法】将自测的我罔9种（含两个地理种群）共10个叩甲科昆虫样品的28SrDNA基因片段序列与GenBank报道的32种叩甲科昆虫进行同一性比较，用DNAStarLasergenev7．1．0和MEGA4．0（NJ法、MP法和ME法）构建分子系统发育树。【结果】在获得的890bp的序列中，保守位点477个，占全部位点的56．1％；简约位点291个，占全部位点的34．2％；G＋C的平均含量为63．9％，明显高于A＋T的平均含量，碱基组成偏向G和C；转换（transition）稍高于颠换（transversion）。遗传距离分析表明叩甲科昆虫各亚科内各种问遗传距离在0．000～0．130之间变动，明显小于各亚科之间的遗传距离。不同的系统发育树都支持叩甲科为一单系群，并将10个亚科聚为4个聚类簇：聚类簇I为梳爪叩甲亚科（Melanotinae）＋叩甲亚科（Elaterinae），聚类簇Ⅱ为槽缝叩甲亚科（Agrypninae）＋萤叩甲亚科（Pyrophorinae）＋单叶叩甲亚科（Conoderinae），聚类簇Ⅲ为小叩甲亚科（Negastriinae）＋心盾叩甲亚科（Cardiophorinae），聚类簇Ⅳ为齿胸叩甲亚科（Denticollinae）＋尖鞘叩甲亚科（Oxynopterinae）和异角叩甲亚科（Pityobiinae）。它们来源于2个支系，支系1包含聚类簇Ⅰ，支系2包含聚类簇Ⅱ、聚类簇Ⅲ和聚类簇Ⅳ，而Senodoniaquadricollis总是单独作为一支与其他叩甲分开。【结论】本研究证实了过去基于成虫和幼虫形态为基础的分类系统的基本合理性，一是叩甲科为一单系类群；二是叩甲科可明显地分为4个簇群；三是心盾叩甲亚科（Cardiophorinae）为一单系类群，但其他许多亚科存在并系的情况，特别是Senodoniaquadricollis的归属还需进一步论证。28SrDNA序列分析是一种很好的研究叩甲科从种级到科级各类群问的系统发育关系的方法。

[ Aims ] To study the molecular phylogenetic relationships of click beetles （Elateridae） based on partial sequences of nuclear 28S ribosomal DNA and comparison with traditional taxonomy results. All these could lay the foundation for the confirmation and further amendment of classification of Elateridae. [ Methods] The fragments of 28S rDNA gene were sequenced from 10 samples for 9 species （including two geographical populations） , of Elateridae, and the sequences for other 32 species of Elateridae were downloaded from GenBank. Molecular phylogenetic trees were reconstructed using software DNA Star Lasergene v 7.1.0 and MEGA4.0 （ NJ, MP and ME methods）. [ Results ] Sequence analysis showed that there were 477 conserved sites, occupying 56. 1% of all sites, and 291 parsim-informative sites, occupying 34.2% of all sites. The average content of G ＋ C was 63.9% , obviously higher than A ＋ T, showing that the base compositions were biased in favor of G ＋ C. Transition value is slightly higher than transversion. The genetic distances within subfamilies ranged from 0. 000 to 0. 130, which were obviously smaller than that among subfamilies. The molecular phylogenetie trees indicated that the 10 subfamilies analyzed were divided into four clades： clade Ⅰ included Elaterinae and Melanotinae, elade Ⅱ included Pyrophorinae, Agrypninae and Conoderinae, clade Ⅲ included Cardiophorinae and Negastriinae, while clade Ⅳ included Denticollinae, Oxynopterinae and Pityobiinae. All ingrou Ptaxa formed two lineages： lineage 1 （ clade Ⅰ ） and lineage 2 （ clades Ⅱ＋Ⅲ ＋Ⅳ ）. Senodonia quadricollis always represented a single lineage, which was separated obviously from other click beetles. [ Conclusions ] This study confirms that traditional taxonomy based on the morphological characteristics of adults and larvae is feasible. At first, the family Elateridae has been proved to be a monophyletic group. The second, the 10 subfamilies of Elateridae can be distinctly divided into four clades. The third, the subfamily Cardiophorinae has been proved to be a monophyletic group, but the other subfamilies were found to be paraphyletic groups, and especially the assignment of Senodonia quadricollis needs further study. The analysis of 28S rDNA gene sequence is proved to be a good way to study the phylogenetic relationships of click beetles.