Abstract
DNA barcoding based on a fragment of the cytochrome c oxidase subunit I (COI) gene in the mitochondrial genome is widely applied in species identification and biodiversity studies. The aim of this study was to establish a comprehensive barcoding reference database of fishes in the Taiwan Strait and evaluate the applicability of using the COI gene for the identification of fish at the species level. A total of 284 mitochondrial COI barcode sequences were obtained from 85 genera, 38 families and 12 orders of fishes. The mean length of the sequences was 655 base pairs. The average Kimura two parameter (K2P) distances within species, genera, families, orders and classes were 0.21%, 6.50%, 23.70% and 25.60%, respectively. The mean interspecific distance was 31-fold higher than the mean intraspecific distance. The K2P neighbor-joining trees based on the sequence generally clustered species in accordance with their taxonomic classifications. High efficiency of species identification was demonstrated in the present study by DNA barcoding, and we conclude that COI sequencing can be used to identify fish species.
Highlights
More than 30,000 species of fish exist worldwide, accounting for more than half of all vertebrates
A total of 284 mitochondrial c oxidase subunit I (COI) barcode sequences were obtained from 85 genera, 38 families and 12 orders of fishes
Convergent and divergent adaptation lead to changes in the morphological characteristics of fish species, imposing great challenges to morphological taxonomy, in which species identification is mainly based on morphological characteristics, and the classification of many species has been controversial[7]
Summary
More than 30,000 species of fish exist worldwide, accounting for more than half of all vertebrates. The identification of fish species mainly relies on morphometric and meristic characters[5]. Fish have remarkable diversity of morphological characteristics, and most fish go through ontogenetic metamorphism. Many morphometric characteristics change during the stages of ontogenetic development[6]. Convergent and divergent adaptation lead to changes in the morphological characteristics of fish species, imposing great challenges to morphological taxonomy, in which species identification is mainly based on morphological characteristics, and the classification of many species has been controversial[7]. The limitations inherent in morphology-based identification systems and the declining number of taxonomists call for a molecular approach to identify species[6, 8]
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