The heritability of larval size is estimated in Mytilus chilensis, based on a nested design, involving 95 full-sib and 19 half-sib families (19 males each mated to 5 separated females) grown under controlled laboratory conditions. The half-sib heritability estimates at 10, 25 and 40 days for larval and spat shell height ranged between 0.38±0.33 and 0.84±0.45, suggesting that selection for shell size would be effective.

Smooth-shelled blue mussels of the Mytilus edulis species complex are widely distributed bivalve molluscs whose introductions threaten native marine b

Genetic differentiation in the Chilean blue mussel Mytilus chilensis (Hupé 1854) was investigated based on the variation in the allozyme frequencies of Pgm, Gpi, Icd, Me, Gsr, Lap and Pep in eight samples collected along 1800 km from Arauco (VIII Region) to Punta Arenas (XII Region). Despite the large geographic separations, values of Neis unbiased genetic distance, D (0.004-0.048) and standardised genetic variation among populations, Fst (0.011-0.055) were small. The levels of gene flow (Nm = 8) found in this study prevent the effect of differentiation among populations by genetic drift. This findings indicate that its long-lived planktotrophic larvae provides this species with considerable dispersal ability throughout its range which is favoured by the ocean currents along the chilean coast. In terms of management of the M. chilensis fishery, the results provide no evidence for discrete stocks, with the possible exception of the Punta Arenas population. Considering the intensive aquaculture activities with this species the present study provide preliminary data which can be used as a baseline for further characterization and /or monitoring these mussel populations

Selection, either natural or artificial, induces an inter-generational response only when the trait exhibits additive genetic variation. An index of additive genetic variation is narrow-sense heritability (h²): the ratio between additive genetic variance and phenotypic variance. Here, we present narrow-sense heritabilities for mass and size in the Chilean blue mussel Mytilus chilensis at different ages and in three different populations. We found that h² changed with age and that maternal-non-additive variance was high, generating relatively low estimates of h² in most cases. Our results, together with previous studies, suggest that genotype-by-environment interaction does not appear to play a significant role. However, we found that non-additive and common environmental variance are important determinants of phenotypic morphological variation in body size in M. chilensis. Further studies are needed to establish the precise contributions of these sources of variation, to assess the real potential for response to selection.