摘要
Partial DNA sequences of three genes, that is, mitochondrial large ribosomal subunit (16S), nuclear large ribosomal subunit (28S D2) and mitochondrial NADH1 dehydrogenase (NADH1) gene, were sequenced from different microgas trine species(Braconidae: Microgastrinae) collected fresh from paddy fields. The DNA sequences were used to determine the extent of sequence variation among species in order to evaluate the specific status of each species. Cladistic analysis was also used to infer a phylogenetic relationship among these species. The results showed that sequence divergence among species of the same genus Cotesia was much lower than those among different genera, such as Cotesia, Exoryza and Apanteles; the sequence similarity of 16S rDNA and NADH 1 genes between Cotesia sp. and C. chilonis was higher than that between C. sp. and C. ruficrus.Phylogenetic analyses suggested that four species of Cotesia were always grouped in the same clade regardless of using different analysis methods; Cotesia sp. and C. chilonis are more closely related to each other than to C. ruficrus, different from previous morphological results. Additionally, sequence analyses indicated that NADH1 gene has more parsimony informative characters than 28S rDNA D2 and 16S rDNA at the species-level analysis,indicating that NADH1 gene might be a useful marker for species-level analysis.
Partial DNA sequences of three genes, that is, mitochondrial large ribosomalsubunit (16S), nuclear large ribosomal subunit (28S D2) and mitochondrial NADH1 dehydrogenase(NADH1) gene, were sequenced from different microgastrine species (Braconidae: Microgastrinae)collected fresh from paddy fields. The DNA sequences were used to determine the extent of sequencevariation among species in order to evaluate the specific status of each species. Cladistic analysiswas also used to infer a phylogenetic relationship among these species. The results showed thatsequence divergence among species of the same genus Cotesia was much lower than those amongdifferent genera, such as Cotesia, Exoryza and Apanteles; the sequence similarity of 16S rDNA andNADH1 genes between Cotesia sp. and C. chilonis was higher than that between C. sp. and C. ruficrus.Phylogenetic analyses suggested that four species of Cotesia were always grouped in the same claderegardless of using different analysis methods; Cotesia sp. and C. chilonis are more closely relatedto each other than to C. ruficrus, different from previous morphological results. Additionally,sequence analyses indicated that NADH1 gene has more parsimony informative characters than 28S rDNAD2 and 16S rDNA at the species-level analysis, indicating that NADH1 gene might be a useful markerfor species-level analysis.
