Genetic divergence of farmed blue mussels (Mytilus sp.) in Australian waters

As valuable ecosystem engineers, blue mussels, are one of the most ecologically and economically important bivalve species in Australia. The need for understanding levels of genetic diversity in both wild and farmed populations of Australian mussels is ever-growing due to the increased risk of disease and decreased fitness associated with the constantly changing global environment. This study, therefore, investigated the phylogenetic relationship, and the genetic variation of farmed blue mussels (Mytilus sp., previously noted as M. galloprovincialis, M. planulatus or a hybrid of both) at four sites along the south coast of Australia, Victoria, South Australia, Western Australia, and Tasmania. Analyses of two genes, Cytochrome c oxidase subunit 1 gene (mtCOI) and the nuclear gene Elongation factor 1 alpha (EF1a) was completed for all mussels sampled. The phylogenetic reconstruction of mtDNA sequences was not able to cluster the samples into species. The analyses of the nuclear marker (EF1a) returned similar results, except that we could conclude the Australian samples not being M. chilensis. Furthermore, the analyses of EF1a revealed the presence of hybridisation, a pattern commonly observed in mussels. The genetic diversity analysis of mtCOI demonstrated that samples from Victoria and Western Australia had the highest genetic diversity, while South Australia had the lowest. When analysing the nuclear EF1a sequences, mussels from Western Australian had the lowest genetic diversity, and the Victorian samples had the highest. The study extended our knowledge on the population genetic variation of farmed blue mussels (Mytilus sp.) along the south coast of Australia. The identified genetic differences between the four southern states of Australia could be interesting for the aquaculture industry when aiming for more adaptable and profitable stocks.