Congruence in genetic markers used to describe Mediterranean and Atlantic populations of European hake (Merluccius merluccius L. 1758)

Eight samples of the hake, Merluccius merluccius L., from the Mediterranean basin (370 fishes total) and one from the Atlantic ocean (50 fishes) were analysed in order to assess genetic variability and describe genetic population structure. Five polymorphic protein coding loci were scored (ADH*, PGI-1*, PGI-2*, PGM* and SOD-1*) in eight samples, together with a haplotype variation of four samples, obtained from polymerase chain reaction/restriction fragment length polymorphism (PCR-RFLP) analysis on the mitochondrial DNA control region. The average value for observed heterozygosity was typically higher than expected (showing an excess of heterozygotes among the samples) whereas the haplotype diversity at mtDNA was very low. Samples originating from inside the Mediterranean basin appeared genetically homogeneous but the sample originating from the Atlantic was heterogeneous compared with the Mediterranean populations. Nuclear and mitochondrial gene analysis showed similar results supporting that the Strait of Gibraltar may be considered as a breakpoint area to gene flow.