Comparative Phylogenetic Study of Four Genes of Mitochondrial Genome in Tenpounder Fishes (Order: Elopiformes)

Abstract

The Elopiformes represent a group of seven known species of fishes found in marine and estuarine ecosystem and many of them are endemic to East Asia. To date published morphological and molecular phylogenetic hypothesis of Tenpounder fishes are part congruent and there are some areas of significant disagreement with respect to species relationships. The present study analyzed the sequence data from four genes (Cytb, CO1, 16S and 12S rRNA) of mitochondrial genome for the attempt to estimate the relationships among five species such as Elops saurus, E. affinis, E. smithi, E. machnata and E. hawaiensis and to assess the phylogenetic utility of these markers. The Kimura 2-parameter (K2P) genetic distance, average nucleotide frequencies, nucleotide substitution patterns and phylogenetic trees were reconstructed using neighbour joining (NJ) method. The interspecies K2P genetic distance was 0.0158 and intraspecies distance was 0.0042 based on the barcoding gene, CO1 sequence data. Whereas the interspecies K2P genetic distance was 0.6140 and intraspecies genetic distance was 0.0020 based on the Cytb data. The four mitochondrial marker genes used in this study showed different type of cluster and we could not confirm the relationship between the five Elops species. This is due to the independent mutation rate of each mtDNA genes. However, this problem can be overcome by analysing in parallel other gene markers.

Exploring the Diversity of Elopidae (Teleostei; Elopiformes) Using DNA Barcoding Analysis

“…In addition, analysis using DNA barcoding does not fully encompass the diversity of Elops. Therefore, it is not surprising that the taxonomy of the species of this genus is problematic, primarily due to anatomical similarities among them [2][3][4].…”

“…Elopidae comprises seven valid species in the single genus Elops and is the most diverse group within the Elopiformes [1,2]. Elopidae includes marine and estuarine fishes that are found globally in tropical and subtropical regions and are mostly allopatric in distribution, although some species may be sympatric [1][2][3][4]. For example, according to Adams et al [1], Elops senegalensis (Regan, 1909) and Elops lacerta (Valenciennes, 1847) are sympatrically distributed in the eastern Atlantic, while Elops saurus (Linnaeus, 1766) and Elops smithi (McBride et al, 2010) are allopatrically distributed in the west, with an overlap of these two species observed in the Gulf of Mexico and southeastern United States.…”

“…However, these diagnostic criteria are subject to problems and inconsistencies, such as the overlap in the number of vertebrae in some species, which can lead to taxonomic errors. In addition, the values for genetic distance based on the cytb gene obtained in previous studies vary widely (Table 1) [1][2][3][4][5][6][7][8]. The taxonomy of Elops species has been the subject of debate in recent years, given their wide distribution and highly conserved anatomical features [3][4][5].…”

“…In addition, the values for genetic distance based on the cytb gene obtained in previous studies vary widely (Table 1) [1][2][3][4][5][6][7][8]. The taxonomy of Elops species has been the subject of debate in recent years, given their wide distribution and highly conserved anatomical features [3][4][5]. For several years, diagnostic criteria for these species have been based primarily on anatomical (e.g., number of vertebrae) and molecular data (genetic distance of the cytochrome b-cytb gene).…”

“…However, these diagnostic criteria are subject to problems and inconsistencies, such as the overlap in the number of vertebrae in some species, which can lead to taxonomic errors. In addition, the values for genetic distance based on the cytb gene obtained in previous studies vary widely (Table 1) [1][2][3][4][5][6][7][8].…”