九种鲱科鱼类线粒体DNA细胞色素b基因相对速率测试及分歧时间估计(英文)

对鲱科9种鱼类的线粒体细胞色素b(cytb)基因序列进行综合分析。结果表明:(1)用Ne ighbour-Join ing(NJ)法构建的分子系统树显示盖纹沙丁鱼属的3种鱼类形成一个单系类群,鲱属2种鱼类形成一个单系类群,它们的bootstrap支持率均为100%。金色小沙丁鱼和短体小沙丁鱼形成一个单系类群,在NJ树中的支持率达到或超过50%。欧洲黍鲱与太平洋鲱和大西洋鲱是单系起源,其bootstrap支持率高达100%。系统发育结果还支持沙丁鱼属鱼类与盖纹沙丁鱼属鱼类是单系类群,支持率分别为87%和95%。但单系类群I(包括大西洋鲱、太平洋鲱、欧洲黍鲱)和单系类群Ⅱ(包括欧洲沙丁鱼、加州沙丁鱼、南美拟沙丁鱼、斑点盖纹沙丁鱼)之间的系统发育关系尚不明确,因为它们之间的支持率很低。(2)dN/dS的比值显著的小于1(Z-test),提示由于功能限制,cytb基因受到强烈的负选择作用。(3)基于Tajim a的1D和2D相对速率测试表明,分子钟假说在鲱科鱼类中是成立的;鲱科鱼类的分歧时间是0.12至13.45百万年间。

Phylogenetic analysis and relative-rate test of nine Clupeidae fishes ( Osteichthyes: Clupeiformes) inferred from cytochrome b gene sequence of mitochondrial DNA

Phylogenetic analysis and relative-rate test of 9 Clupeidae fishes were performed using thecytochromeb(cytb) gene sequence data.Based on Kimura-2-Parameter(K2P) distance,bootstrapped NJ tree(1000 replicates) was generated from these 9 cytb gene sequences of Clupeidae fishes.Three species of genusSardinopsare monophyletic group,2 species of genusClupeaare monophyletic group,and their bootstrapvalues are both 100%.Sardinella auritaandSardinella maderensisare monophyletic group,their bootstrapvalue reached or exceed 50%.Sprattus sprattuswhich is a species of genusSprattus,has a monophyleticorigin with genusClupea,their bootstrap value was 100%.The number of synonymous nucleotide substitutionper synonymous site(dS) and the number of nonsynonymous nucleotide substitution per nonsynonymous site(dN) of cytb gene among Clupeidae fishes were calculated.The ratios of dN/dS were significantly less than 1by Z-test,which suggest that purifying selection may operate on the cytb gene for strong functionalconstraints.Relative-rate test which was based on Tajima's 1D and 2D tests suggested that molecular clockheld within Clupeidae fishes,and the divergenttime ranged from0.12 to13.45 million years within Clupeidaefishes.