黄海沙带鱼的DNA条形码鉴定及其分布

为了对沙带鱼(Lepturacanthus savala)进行有效的分类鉴定, 明确目前黄海海域是否存在沙带鱼的自然分布, 本研究在形态学描述与测量的基础上, 利用 DNA 条形码技术对沙带鱼及其近缘种进行了分析。共采集了来自黄海、东海(台湾海峡)及南海(北部湾)的疑似沙带鱼样品 16 尾及其近缘种样品 1 尾, 测定并获取 DNA 条形码序列 17 条。结合已报道的带鱼科 8 种鱼类的 18 条 DNA 条形码序列对全部样品进行了物种鉴定, 运用 Kimura 2-parameter (K2P)模型构建了其系统进化关系。研究结果显示: 全部疑似沙带鱼样品的 DNA 条形码序列均与 GenBank 中沙带鱼(L. savala)的对应序列具有最高的相似性; 沙带鱼的种内遗传距离远小于其与同属罗氏沙带鱼(Lepturacanthus roelandti)的种间遗传距离; 在系统发育树中, 全部的疑似沙带鱼均与已发表的沙带鱼 DNA 条形码序列聚为一支。 研究结果表明, DNA 条形码技术可弥补形态学方法在沙带鱼及其近缘种鉴定中的不足, 实现沙带鱼的有效鉴定; 与此同时, 本研究进一步证实了沙带鱼在黄海的存在, 结果可为黄海沙带鱼资源的保护和可持续利用提供科学依据。

DNA barcoding for identification of Lepturacanthus savala (Scombriformes, Trichiuridae) in the Yellow Sea and the geographical distribution of the species

Lepturacanthus savala (Cuvier, 1829), commonly called spiny hairtail, is an economically important species in the family Trichiuridae, with a wide distribution in the Indian-Western Pacific coastal waters. Overfishing and changes in the ecological environment of fisheries have created a severe impact on the natural resources of L. savala at present. However, the species identification and taxonomic classification of L. savala are controversial because of its variable morphology and high levels of similarity between related species. The geographical distribution of L. savala has also not been systematically researched, and whether the species exists in the Yellow Sea was unknown. In recent years, DNA barcoding has been proposed as a useful molecular technique to complement traditional taxonomic expertise, and it has provided an important tool for species identification and biodiversity inventories. In this study, we used DNA barcoding to effectively identify L. savala and clarify the existence of the species in Yellow Sea. We examined a DNA barcode fragment of 645 base pairs of the mitochondrial cytochrome c oxidase subunit I (COI) gene from 16 suspected L. savala individuals collected from the Yellow Sea, East China Sea (Taiwan Strait) and South China Sea (Beibu Gulf). Homologous sequences from closely-related species were also included in the comparative analysis and species identification. Phylogenetic relationships among eight species of the family Trichiuridae were reconstructed using neighbor joining (NJ) based on Kimura-2 parameter (K2P) net genetic distance. Sequence analysis showed that the genetic distance between suspected L. savala and actual L. savala was 0.6%, significantly lower than the interspecific genetic distance of 13.9% between L. savala and its only congeneric species, L. roelandti. Phylogenetic analysis showed that all DNA barcoding sequences of suspected L. savala clustered in the same group with L. savala, and also had a close genetic relationship with L. roelandti. These results indicated that all the suspected L. savala individuals could be identified as L. savala in this study, and we conclude that the DNA barcoding can be used to identify species in the family Trichiuridae. Our results also provide strong evidence for the existence of L. savala in the coastal waters of the Yellow Sea and enriched our knowledge of geographical distribution and genetic diversity of the species.