Molecular Characterization of Charru Mussels (Mytella charruana) from Three Selected Sites in Luzon Using Matrilineal mtCO1 Gene Sequences

Abstract

The presence of Mytella charruana, commonly known as charru mussels, was first recorded in the Philippines in 2014 and has recently been reported as invasive (Vallejo et al., 2018). Recently, accounts have shown that the bivalve has been observed in several other areas in Luzon. As this species is being cultured by the Bureau of Fisheries and Aquatic Resources (BFAR) as food source, there is a need to investigate the spread of this species and its capacity to invade our areas. This study assessed whether the Mytella found in the three sites of Luzon (Manila Bay, Bolinao and Dagupan City, Pangasinan) were similar based on their matrilineal mtCO1 gene sequences. Mytella samples were initially identified by morphology and then were subjected to biochemical tests to determine which were female. The mtCO1 gene sequence of each sample was then obtained, amplified and subjected to BLASTn searches. Results from the BLASTn showed that 16 of the samples were closely identical (mean=99.27%) to Mytella strigata (=charruana) and two samples were highly identical (mean=99.24%) to Mytella charruana. The phylogenetic trees supported the results of the BLASTn searches. Haplotype network analysis showed that the Philippine populations of Mytella charruana were closely linked to the populations from Panama, Colombia and Singapore. Moreover, two new unique haplotypes, 6BANIBA6 and 4BFARBF4, were found in this study. Admixture of different source populations may have caused these recent mutations. The analysis of the relationship among the three selected Mytella populations in Luzon, the native South Caribbean populations, and the invasive Singaporean populations is significant as it provides insight on the bivalve’s source and spread.