Ecological Genetics of the Mussels Mytilus edulis and M. galloprovincialis on Irish Coasts

Abstract

Genetic polymorphism at the loci encoding the enzymes phosphoglucose isomerase, leucine aminopeptidase and phosphoglucomutase was investigated in Irish Mytilus populations. Allele frequencies and heterozygote proportions indicated that populations on exposed Atlantic coasts differed from those on sheltered Atlantic coasts, and from Irish Sea mussels. When compared with data on M. edulis collected in northern France and M. galloprovincialis from the Mediterranean these data indicate that in Ireland M, galloprovincialis occurs mainly at exposed sites, and hybridization with M. edulis occurs frequently. The systematic status of the two forms remains uncertain In the l ~ g h t of genetic evidence of hybridization and intergradation between them.