GENETIC-CHARACTERIZATION OF THE HYBRIDIZATION BETWEEN MYTILUS-EDULIS AND MYTILUS-GALLOPROVINCIALIS ON THE ATLANTIC COAST OF FRANCE

A genetic study carried out on nine natural mussel populations on the French Atlantic coast from 1989-1990 revealed interdigitation between typically Mytilus edulis and typically M. galloprovincialis populations and intermediate populations. The allele components of the populations followed a M. edulis/M. galloprovincialis gradient which does not correspond to a geographical gradient. Strong hybridization was evident in samples with intermediate allele frequencies. The respective importance of gene flow and selection is discussed in the light of the results and the environmental features of the sampling zone.