THE GENETIC-RELATIONSHIPS OF 3 TAXA IN THE LITTORINA-SAXATILIS SPECIES COMPLEX (PROSOBRANCHIA, LITTORINIDAE)

Three species in the Littorina saxatilis complex (the ovoviviparous L. saxatilis and the two oviparous species L. arcana and L. nigrolineata) were screened for the products of up to 22 loci using gel electrophoresis. Analysis of allele frequencies and derived genetic distances showed that, with rare exceptions in L. saxatilis and L. arcana, conspecific populations clustered together. Sympatric pairs of populations showed significant differentiation at many polymorphic loci. The results confirmed the biological reality of the three taxa, and did not suggest the existence of any previously unrecognized species. The species are genetically closely related to each other, with Nei genetic distances ranging from 0.035 to 0.083.