ANALYSIS OF A NUCLEAR-DNA MARKER FOR SPECIES IDENTIFICATION OF ADULTS ANDLARVAE IN THE MYTILUS EDULIS COMPLEX

Abstract

The advent of polymerase chain reaction (PCR)-based DNA markers, which claim to identify species diagnostically in the Mytilus edulis complex (M. edulis, M. galloprovincialis and M. trossulus) presents a possible method for simple, rapid species identification of Mytilus larvae. This study examines the inheritance of the Me 15/16 nuclear-DNA locus, which has previously been shown to produce three alleles diagnostic for M. edulis, M. galloprovincialis and M. trossulus. The Me 15/16 genotype was determined for pure species and hybrid larvae from 13 laboratory crosses between these three species and for adult mussels from five natural populations from which the parents of the crosses were selected. Genotype frequencies in the parent populations were generally as expected for M. edulis and M. galloprovincialis, but M. trossulus populations from eastern Canada and the Baltic Sea gave unexpected results. The marker was readily detected in individual larvae sampled 72 h and 2 weeks after fertilization, but amplification from 3 h old larvae was less reliable. Each cross produced larvae of all the expected genotypes and the results demonstrate that each of the three alleles can be inherited from either sex. The marker appears to be inherited in a Mendelian manner and should be of potential use in the future study of larvae in the M. edulis complex.