Allozyme and microsatellite diversity in natural and domestic populations of turbot (Scophthalmus maximus) in comparison with other Pleuronectiformes

Abstract

Twelve microsatellite and 28 allozyme loci were employed to analyse genetic diversity in natural and domestic populations of turbot (Scophthalmus maximus) from northwest Spain in comparison with other flatfish species with similar habitat, life history, and geographic distribution—the brill (Scophthalmus rhombus) and the flounder (Platichthys flesus). These species had shown much higher allozyme diversity than turbot in previous studies, and were used as a reference to check for putative historical bottlenecks in turbot. Significantly lower genetic variability in turbot than in brill and flounder was confirmed with allozymes, but not with the highly variable microsatellite loci. This intermarker discrepancy could be explained by different mutation rates in relation with historical bottlenecks along turbot evolution. A significantly lower genetic diversity was observed in a domestic strain of turbot than in natural populations of this species. This sample evidenced a strong family structure from microsatellite data, which suggests caution against the use of commercial batches for broodstock foundation in turbot farming. A strong concordance was found across the two categories of markers used when analysing the pattern of genetic subdivision at a local scale within the three species analysed, low and nonsignificant genetic differentiation being observed between Atlantic and Cantabric areas.