Molecular characterization of marine and coastal fishes of Bangladesh
through DNA barcodes
Abstract
Abstract: This study attempted to molecular characterization of marine
and coastal fishes of Bangladesh based on mitochondrial cytochrome c
oxidase subunit I (COI) gene as a marker. A total of 376 mitochondrial
COI barcode sequences were obtained from 185 species belonging to 146
genera, 74 families, 20 orders and two classes of fishes. The mean
length of the sequences was 652 base pairs. For all the samples, %G was
significantly lower compared to the other nucleotides and %GC was
significantly lower compared to %AT (p ˂ 0.005). Also, a significantly
lowered %GC content was observed in second and third codon position
compared to the first codon position in all the samples
(1st>2nd>3rd, p-value ˂ 0.005). In
Elasmobranchii (Sharks and rays) the average Kimura two parameter (K2P)
distances within species, genera, families and orders were 1.2%,
6.07%, 11.08% and 14.68%, respectively and for Actinopterygii, the
average K2P distances within species, genera, families and orders were
0.40%, 6.36%, 14.10% and 24.07%, respectively. The mean interspecies
distance was 16-fold higher than the mean intraspecies distance. The K2P
neighbor-joining (NJ) trees based on the sequences generally clustered
species in accordance with their taxonomic position. A total of 21
species were newly recorded in Bangladesh. High efficiency and fidelity
in species identification and discrimination were demonstrated in the
present study by DNA barcoding, and we concluded that COI sequencing can
be used as an authentic identification marker for Bangladesh marine fish
species. Key words: COI, Barcoding, Elasmobranchii, Actinopterygii,
Genetic diversity, Phylogeny