基于28S rDNA D2基因片段与形态特征的优茧蜂亚科系统发育研究

本研究选取优茧蜂亚科Euphorinae(膜翅目Hymenoptera:茧蜂科Braconidae)的8族19属23种作为内群,茧蜂其它6个亚科的8属8种作外群,首次结合同源核糖体28S rDNA D2基因序列片段和41个形态学特征对该亚科进行了系统发育学研究。利用"圆口类"的内茧蜂亚科Rogadinae、茧蜂亚科Braconinae、矛茧蜂亚科Doryctinae的3个亚科为根,以PAUP*4.0和MrBayes3.0B4软件分别应用最大简约法(MP)和贝叶斯法对优茧蜂亚科的分子数据和分子数据与非分子数据的结合体进行了分析;并以PAUP*4.0对优茧蜂亚科的28S rDNA D2基因序列的片段的碱基组成与碱基替代情况进行了分析。结果表明:优茧蜂亚科的28S rDNA D2基因序列片段的GC%含量在40.00%~49.25%之间变动,而对于碱基替代情况来讲,优茧蜂亚科各个成员间序列变异位点上颠换(transversion)大于转换(transition);不同的分析和算法所产生的系统发育树都表明目前根据形态定义出的优茧蜂亚科Euphorinae不是一个单系群,而是一个与蚁茧蜂亚科Neoneurinae和高腹茧蜂亚科Cenocoelinae混杂在一起的并系群;在优茧蜂亚科内部,悬茧蜂族Meterorini和食甲茧蜂族Microctonini(排除猎户茧蜂属Orionis)为单系群,而宽鞘茧蜂族Centistini、大颚茧蜂族Cosmophorini、优茧蜂族Euphorini、瓢虫茧蜂族Dinocampini为并系群;悬茧蜂族Meterorini在优茧蜂亚科Euphorinae内位于基部位置的观点得到部分的支持,同时食甲茧蜂族Microctonini被判定为相对进化的类群。此外对于优茧蜂亚科内各属之间的相互亲缘关系,不同算法所得到的系统发育属的结果不完全一致,这表明优茧蜂亚科内(属及族)的系统发育关系还有待于进一步研究。

Phylogenetic Relationships of the Subfamily Euphorinae(Hymenoptera:Braconidae) Based on the D2 Variable Region of 28S rDNA and Morphological Characters

This study is the first attempt to combine gene sequences with morphological characters to provide a phylogenetic reconstruction of the subfamily Euphorinae (Hymenoptera:Braconidae).Twenty three species belonging to 8 tribes 19 genera of the subfamily were involved,and eight species of eight genera belonging to six subfamilies of Braconidae were used as outgroups with Rogadinae,Braconinae and Doryctinae usd as"root"to testify the monophyletic nature of the subfamily.Four new DNA sequences of D2 region of 28S ribosomal were amplified and submited to GenBank.Forty one characters of morphology were selected and analyzed in a cladistic manner.The evolutionary relationships were investgated by comparing the results from molecular data alone or molecular data combined morphological characters using different analysis methods:maximum parsimony(MP)by PAUP* 4.0 and Bayesian inference by MrBayes 3.0B4.Base composition and ti/tv of 28S rDNA D2 regions were analyzed by PAUP*4.0.The results showed that GC content of the 28S rDNA D2 gene sequences of subfamily Euphorinae ranges from 40.00%to 49.25%.Transversion frequency of sequence variable sites among species of Euphorinae was higher than that of transition.The subfamily Euphorinae was proved to be a paraphyletic group with close relationship to subfamilies Neoneurinae and Cenocoelinae;only two tribes,Meterorini and Microctonini(except genus Orionis), were proved to be monophyletic groups;Centistini,Cosmophorini,Euphorini and Dinocampini were paraphyletic groups;the basal position of tribe Meterorini within Euphorinae was partially supported by our phylogenetic trees,and tribe Microctonini was proved to be a group at the top of the trees.There was no absolute consistency between the topologies of phylogenetic trees generated by different analysis methods with different data,suggesting that more work should be done to resolve the phylogenetic relationships among genera and tribes of the subfamily Euphorinae.