Comparative analysis of shell frame characteristics and mitochondrial 16S rRNA gene between wild and cultured mussels (Mytilus coruscus)

Understanding the impact of the environment of Mytilus unguiculatus on its growth is extremely important for promoting high-quality development of mussel breeding industry. Taking the wild (From Gouqi intertidal area) and cultured (From mussel culture rafts) M. coruscus as research objects, we constructed 13 shell frame characteristics indexes based on shell length, including shell width and shell height to compare their main morphological differences, and sequenced their 16S rRNA gene to analyze the genetic and morphological associations between them. The results show that there were significant differences in ten shell frame characteristics between wild and cultured mussels (P<0.05), and the shells of wild mussels were generally wider, thicker and heavier. Four variables were selected by stepwise discrimination method: L₁ (Shell width), L₂ (Shell height), L₁₀ (Distance from the top of shell to the upper end of hinge), L₁₂ (Distance from the top of shell to the byssus orifice). The comprehensive discrimination accuracy of wild and cultured mussels was 94.9%. The 16S rRNA gene sequencing shows that the wild mussels nucleotide diversity (π) was 0.089, and haplotype diversity (H_d) was 0.894; cultured mussels' π was 0.087 and H_d was 0.682. The genetic diversity level of wild and cultured mussles were relatively high, but the phylogenetic tree and haplotype network prove that there was no significant genetic differentiation between them. It is speculated that their morphological differences might be mainly influenced by their habitat environments (Wave exposure, growth density, etc.).