Genetic Evidence for Naturally Occurring Hybrids Between Mytilus edulis and Mytilus galloprovincialis

TitleGenetic Evidence for Naturally Occurring Hybrids Between Mytilus edulis and Mytilus galloprovincialis
Publication TypeJournal Article
Year of Publication1978
Refereed DesignationRefereed
AuthorsSkibinski, D. O. F., Ahmad M., & Beardmore J. A.
JournalEvolution
Volume32
Issue2
Pagination354-364
Abstract

The two mussels Mytilus edulis and M. galloprovincialis live sympatrically in southwest Engand. Data are presented for populations at Croyde in North Devon and Rock in North Cornwall which show that the two types differ greatly in allele frequencies at three polymorphic loci (esterase-D, leucine aminopeptidase-1, and phosphohexose isomerase), and that samples from the populations show large deficits of heterozygotes and strong associations of genotypes among the loci. These results are interpreted as evidence that the two types are at least partially isolated. Samples of morphologically intermediate individuals are shown to contain a large excess of genotypes heterozygous for different alleles each of which is frequent in one, but infrequent in the other, of the two types. This provides good evidence that hybridization occurs in nature. The proportion of F1 hybrids is estimated to be 5.4% and 2.1% at Croyde and Rock respectively. The results are discussed in relation to evolutionary theory concerning hybridization and speciation, genetic variation in Mytilus and the taxonomic status of M. edulis and M. galloprovincialis.