线粒体DNA序列分析在中国水域真海豚物种鉴定中的初步应用

真海豚包括长喙真海豚( Delphinus capensis) 和短喙真海豚( D. delphis) 2 种, 而中国水域的真海豚到底是哪一个种或是否同时有两个种的存在, 并不清楚。本研究测定了12 头中国水域真海豚mtDNA 控制区(control region) 366 bp 和细胞色素b (cytochrome b , cyt b) 基因336 bp 的序列, 并与已发表的其它真海豚的序列合并分析,初步鉴定中国水域真海豚的分类地位。结果表明, 中国水域的真海豚与东太平洋的长喙真海豚有相同的鉴别位点, 且两者之间的核苷酸歧异度(控制区: 1.93 ±0.22 % , cyt b 基因: 0.68 ±0.19 %) 显著低于与短喙真海豚之间的差异(控制区: 2.92 ±0.41 % , cyt b 基因: 0.95 ±0.27 %) 。通过MEGA (molecular evolutionary genetic analysis) 软件中的邻接法(neighbor joining) 进行的系统发生分析中, 中国水域的真海豚与长喙真海豚聚成一支, 有明显较近的亲缘关系。因此, 中国水域的真海豚在分类上应归属于长喙真海豚。

Application of Mitochondrial DNA Sequences in the Species Identification of Common Dolphins (Genus Delphinus) in Chinese Waters

Common dolphins, genus Delphinus, are regarded to be composed of two species, i.e., long-beaked common dolphins (D. capensis) and short-beaked common dolphins ( D. delphis). However, the taxanomic status of Chinese common dolphins is still uncertain up to date. In this study, 366 base pairs (bp) of mitochondrial DNA (mtDNA) control region and 336 bp of mitochondrial cytochrome b (cyt b) gene from 12 common dolphins collected in Chinese waters were sequenced and combined with previously published homologous sequences of common dolphins from the Eastern Pacific waters, to address the systematic status and patterns of genetic variation of common dolphins in Chinese waters. Sequence comparison showed that the Chinese common dolphins share the same diagnostic site with recognized long-beaked common dolphins from the Eastern Pacific waters. The sequence divergence between haplotypes from Chinese common dolphins and long-beaked dolphins was much lower than that from short-beaked common dolphins. Phylogenetic tree reconstructed by using neighbor-joining algorithm implemented in the computer software MEGA (molecular evolutionary genetic analysis) version 2.0 found a monophyletic clade including Chinese common dolphins and long-beaked common dolphins, suggesting a relatively close relationship between them. Therefore, the Chinese common dolphins should be referred to as long-beaked common dolphins, Delphinus capensis.