Genetic identification of Thunnus orientalis, T. thynnus, and T. maccoyii by a cytochrome b gene analysis

Abstract

The three species of bluefin tunas, Thunnus orientalis, T. maccoyii, and T. thynnus, are morphologically similar, which can pose problems for fisheries management and marketing. We examined intraspecific genetic diversity and interspecific genetic boundaries among these three species by analyzing the cytochrome (Cyt) b gene. The full lengths of the nucleotide sequences were 1,141 bp in T. orientalis and T. thynnus and ranged 1,138~1,141 bp in T. maccoyii. Mean nucleotide diversities were 0.0019± 0.0002 in T. thynnus (n=8), 0.0063±0.0005 in T. orientalis (n=22), and 0.0059±0.0007 in T. maccoyii (n=24). Average numbers of nucleotide differences and nucleotide substitutions per site among the three species were 18.748±2.879 and 0.017±0.003, respectively. The Neighbor-joining and minimum-evolution trees showed distinct clades with high bootstrapping value support, and the high Fst value indicated significant differentiation among the three species. T. thynnus, T. orientalis, and T. maccoyii could be individually distinguished from each other Thunnus tunas by the 132nd, 375th, and 1,023rd sites of the Cyt b sequences. In the mismatch analysis, Fu's and Tajima's tests of sequences from T. orientalis and T. maccoyii provided evidence of their population expansion dating to the middle Pleistocene.

Mitochondrial DNA Diversity of Terubok (Tenualosa toli) from Daro and Mukah, Sarawak Inferred by Partial Cytochrome b (Cyt-B)

“…The use of mitochondrial Cyt-b gene to perform the analysis of genetic diversity and population genetic structure studies had been done in many closely related fishes (Norfatimah et al, 2009;Pereyra et al, 2010;Tseng et al, 2011). The gene also holds viable information regarding the phylogenetic relationships within and between the individuals of the same population.…”

Interspecific and Intraspecific Genetic Diversity of Thunnus Species

“…Two sets of primers and amplification conditions were used to amplify the complete Cyt b gene and control region of mtDNA (Tseng et al, 2009(Tseng et al, , 2011. Amplification was performed in a BIO-RAD MJ Mini Gradient Thermal Cycler (Conmall Biotechnology, Singapore).…”

Phylogenetics and Molecular Divergence of Tilapia Fish (Oreochromis Species) Using Mitochondrial D-Loop and Cytochrome b Regions

“…These features of mtDNA are used by evolutionary biologists to establish relationships and to trace maternal lineage of species using array of sequence data. The displacement loop (D-loop) is the most variable region of mtDNA [19] and previous research reported that high variation in the region is useful in characterizing tilapia species [20] [27]. In the present study, it was our aim to assess the phylogenetics of Oreochromis niloticus, a common species of tilapia fish in Nigeria using mitochondrial D-loop and Cytb.…”