北京地区7种常见嗜尸性蝇类的COI基因序列分析及DNA条形码的建立

嗜尸性蝇类在命案死亡时间和现场推断方面有着十分重要的应用, 而DNA 条形编码技术能摆脱对虫卵和幼虫的饲养以及后续物种鉴定方面专业知识的依赖, 有助于实现现场采集蝇类样本的快速鉴定。本研究采集了北京地区7个嗜尸性蝇类优势种共77个个体的样本, 测定了所有个体线粒体DNA 上细胞色素C氧化酶亚基Ⅰ（COI）基因1 120 bp的序列。基于序列的系统发生分析显示, 同一物种不同个体的序列均以高达99%的支持值聚集在一起。序列间的分歧统计表明这些蝇类在物种内的个体分歧不超过1%, 而不同物种间的净分歧均超过7.74%, 最高可达14.85%。滑动窗口分析表明, 在整个序列区段种间差异位点存在较平均的分布。通过测定COI基因的序列, 建立了北京地区7个嗜尸性蝇类优势种的DNA条形码, 据此实现了对这些物种准确、快速、简单的区分和鉴定, 同时也为后续应用于物种鉴定的种属特异性位点之筛选提供了基础数据。

Sequential analysis of mitochondrial COI gene for seven common sarcosaphagous flies (Diptera) in Beijing and the establishment of their DNA barcodes

Sarcosaphagous flies have very important applications in death time estimation and crime scene reconstruction for homicide cases. DNA barcoding technology can extricate the investigators from the difficulty of culturing eggs and larvae of these flies as well as the reliance on special knowledge to scientifically identify the following imagoes, which is of great help for rapid identification of fly samples collected at the crime scene. We collected 77 samples, which belong to 7 dominant species of sarcosaphagous flies in Beijing, from different districts, and sequenced a 1 120 bp region of the mitochondrial cytochrome oxidase subunit I (COI) gene for each individual. Phylogenetic analysis showed that individual sequences of each species highly clustered together with 99% bootstrap support. Sequence divergences within species were less than 1%, while net divergences between species were all greater than 7.74%, the highest reaching 14.85%. Sliding window analysis demonstrated that variable sites for all species were relatively equally distributed along the entire region. By sequencing part of the COI gene, we established the DNA barcodes for the seven dominant species of sarcosaphagous flies in Beijing, which realized the accurate, rapid, and easy identification of these species and provided basic material for the future selection of variable sites that can be used for direct identification of sarcosaphagous flies.