Department of Life Science, Tunghai University, Taichung, Taiwan.
Gene. 2010 Nov 15;468(1-2):20-9. doi: 10.1016/j.gene.2010.08.001. Epub 2010 Aug 8.
This study determined the first complete mitochondrial genome of a damselfly, Euphaea formosa (Insecta: Odonata: Zygoptera), and reconstructed a phylogeny based on thirteen protein-coding genes of mitochondrial genomes in twenty-five representative hexapods to examine the relationships among the basal Pterygota. The damselfly's mitochondrial genome is a circular molecule of 15,700bp long, and contains the entire set of thirty-seven genes typically found in insects. The gene arrangement, nucleotide composition, and codon usage pattern of the mitochondrial genome are similar across the three odonate species, suggesting a conserved genome evolution within the Odonata. The presence of the intergenic spacer s5 likely represents a synapomorphy for the dragonflies (Anisoptera). Maximum parsimony, maximum likelihood, and Bayesian analyses of both nucleotide and amino acid sequences cannot support the three existing phylogenetic hypotheses of the basal Pterygota (Palaeoptera, Metapterygota, and Chiastomyaria). In contrast, the phylogenetic results indicate an alternative hypothesis of a strongly supported basal Odonata and a sister relationship of the Ephemeroptera and Plecoptera. The unexpected sister Ephemeroptera+Plecoptera clade, which contradicts with the widely accepted hypothesis of a monophyletic Neoptera, requires further analyses with additional mitochondrial genome sampling at the base of the Neoptera.
本研究确定了豆娘 Euphaea formosa（昆虫纲：蜻蜓目：均翅亚目）的首个完整线粒体基因组，并基于二十五个代表性六足动物的线粒体基因组的十三个蛋白质编码基因重建了系统发育树，以检验基干有翅类动物之间的关系。该豆娘的线粒体基因组是一个长 15700bp 的圆形分子，包含昆虫中常见的整套 37 个基因。线粒体基因组的基因排列、核苷酸组成和密码子使用模式在三种蜻蜓物种中相似，表明在 Odonata 内存在保守的基因组进化。基因间隔区 s5 的存在可能代表了蜻蜓目（Anisoptera）的一个并系特征。基于核苷酸和氨基酸序列的最大简约法、最大似然法和贝叶斯分析均不能支持基干有翅类动物（古翅类、次生翅类和原翅类）的三个现有系统发育假说。相比之下，系统发育结果表明一个强烈支持的基干蜻蜓目以及蜉蝣目和襀翅目之间的姐妹关系的替代假说。出乎意料的是蜉蝣目+襀翅目姐妹群与广泛接受的单系新翅类假说相矛盾，需要在新翅类的基部进行额外的线粒体基因组采样的进一步分析。
