Mitogenomic Analysis of Pterioidea (Bivalvia: Pteriomorphia): Insights into the Evolution of the Gene Rearrangements

The complete mitogenomes of Pinctada albina and Pinctada margaritifera were sequenced in this study, with sizes of 23,841 bp and 15,556 bp, respectively. The mitochondrial genome analysis of eight Pterioidea species indicated the existence of gene rearrangements within the superfamily. The ATP8 gene was not detected in the two new mitogenomes, and rrnS was found to be duplicated in P. albina’s mitogenome. The reconstructed phylogeny based on mitogenomes strongly supported the monophyly of Pterioidea and provided robust statistical evidence of the phylogenetic relationships within Pteriomorphia. The analysis of the mitochondrial gene order revealed that of P. margaritifera to be the same as the ancestral order of Pterioidea. The gene orders of the Pterioidea species were mapped to the phylogenetic tree, and the gene rearrangement events were inferred. These results provide important insights that will support future research, such as studies extending the evolutionary patterns of the gene order from P. margaritifera to other species and determining the evolutionary status of Pterioidea within the infraclass Pteriomorphia.