Mitogenomic Architecture and Phylogenetic Relationship of European Barracuda, Sphyraena sphyraena (Teleostei: Sphyraenidae) from the Atlantic Ocean

Abstract

The collective understanding of global-scale evolutionary trends in barracuda mitogenomes is presently limited. This ongoing research delves into the maternal evolutionary path of Sphyraena species, with a specific focus on the complete mitogenome of Sphyraena sphyraena, sourced from the Atlantic Ocean through advanced next-generation sequencing. This mitogenome spans 16,841 base pairs and encompasses 37 genes, including 13 protein-coding genes (PCGs), 2 ribosomal RNA genes (rRNAs), 22 transfer RNA genes (tRNAs), and an AT-rich control region. Notably, the mitogenome of S. sphyraena exhibits a preference for AT-base pairs, constituting 55.06% of the composition, a trait consistent with a similar bias found in related species. Most protein-coding genes initiate with an ATG codon, with the exception of Cytochrome c oxidase I (COI), which begins with a GTG codon. Additionally, six PCGs terminate with a TAA codon, COI with AGA, while six others exhibit incomplete termination codons. In the S. sphyraena mitogenome, the majority of transfer RNAs exhibit typical cloverleaf secondary structures, except for tRNA-serine, which lacks a DHU stem. Comparative analysis of conserved blocks within the D-loop regions of six Sphyraenidae species reveals that the CSB-I block extends to 22 base pairs, surpassing other blocks and containing highly variable sites. Both maximum-likelihood and Bayesian phylogenetic analyses, using concatenated 13 mitochondrial PCGs, distinctly separate all Sphyraenidae species. The European Barracuda, S. sphyraena, demonstrates a sister relationship with the ‘Sphyraena barracuda’ group, including S. barracuda and S. jello. In conclusion, this study advances our understanding of the evolutionary relationship and genetic diversity within barracudas. Furthermore, it recommends comprehensive exploration of mitogenomes and broader genomic data for all existing Sphyraenidae fishes, providing invaluable insights into their systematics, genetic characterization, and maternal evolutionary history within marine environments.