Molecular evolution of Clupeidae fishes ( Osteichthyes:Clupeiformes) :information obtained from Genbank database
【摘要】：正Molecular evolution characteristics of 9 Clupeidae fishes were studied using the cytochrome b (cytb) gene sequence data obtained from Genbank database. The results indicate that (1) The cytb genes of Clupeidae fishes have the similar characters with other fishes and vertebrates in both base composition and base substitutions, and (2) Based on different DNA substitutional models, bootstrapped NJ trees (1000 replicates) were generated from these 9 cytb gene sequences of Clupeidae fishes. Three genus Sardinops fishes are monophyletic group, 2 genus Clupea fishes are monophyletic group, and bootstrap values are both 100%. Sardinella aurita and S. maderensis are monophyletic group, their bootstrap value reached or exceed 50%. Sprattus sprattus, which belongs to genus Sprattus, has a monophyletic origin with genus Clupea, and their bootstrap value was 100% and (3) The number of synonymous nucleotide substitution per synonymous site (Ks) and the number of nonsynonymous nucleotide substitution per nonsynonymous site (Ka) of cyti gene between Clupeidae fishes were calculated, the ratios of Ka/Ks which are significantly less than 1 by Z-test suggest that purifying selection may operate on the cytb gene for stronger functional constraints, and (4) relative-rate test based on Tajima's 1D and 2D tests suggested that molecular clock hold within Clupeidae fishes, and the divergent time ranged from 0. 15 to 6. 93 million years between them.