No evidence for genetic differentiation of the mussel Mytilus galloprovincialis between lagoons and the seaside

Twelve locations of Mytilus galloprovincialis were sampled in lagoons and a long the seaside in southern France. Lagoons represent a habitat with widel y varying ecological conditions. Each lagoon has its own characteristic ran ge of salinities and temperatures which fluctuate throughout the year. We s tudied several fundamental parameters of the population genetics of M. gall oprovincialis at 8 enzymatic loci (genetic differentiation between location s, heterozygote deficits, selection, linkage disequilibrium) and investigat ed whether they are influenced by the high spatial and temporal instability of the lagoons (brackish water). In contrast to what could be expected bas ed on the corresponding literature, we found no evidence for genetic differ entiation, either among lagoons or between lagoons and the seaside. There w as, thus, no evidence of selection on any of the loci studied.