Comparative Mitogenome Analyses Uncover Mitogenome Features and Phylogenetic Implications of the Rabbitfishes...

Mitochondria are essential for energy metabolism in coral reef fish, and mitogenomes represent valuable genetic resources for phylogenetic analysis and species identification. To investigate the lineage variation and phylogenetic relationships, we obtained the first complete mitochondrial genome sequences of four Siganidae species (Siganus argenteus, S. corallinus, S. punctatus, and S. spinus) and conducted comparative analyses with 10 published mitogenomes from this family. Results revealed that siganid mitogenomes were highly conserved in gene content, organization, and base composition. Phylogenetic analysis based on 13 protein-coding genes (PCGs) classified the Siganidae family into three major clades, which corresponded to divergent ecological habits and morphological characteristics. The control region of mitogenome exhibited the greatest interspecific variability. Structural variations in tRNAs and the Origin of Light-Strand Replication (O _L ) were largely consistent with the mitochondrial phylogeny inferred from PCGs. Selection pressure analysis indicated that purifying selection dominates all PCGs, with varying selective constraints among genes. Notably, nad5 showed the most purifying selection sites and atp8 showed the fewest, suggesting their potential as markers for siganid species identification. All data and findings generated herein constitute a valuable resource for future siganid research, laying a foundation for evolutionary exploration and coral reef biodiversity conservation.