Genetic differentiation between populations of Pomatoschistus minutus from the Bristol Channel and the Adriatic

Samples from two populations of the gobiid fish species Pomatoschistus minutus (Pallas) were compared electrophoretically over 31 protein loci. The population from the Lagoon of Venice was shown to possess an extra LDH staining region, not present in P. minutus from Wales or any other congeneric population. The manifestation of this additional LDH band is strongly suggestive of a distinct genetic locus. The two populations have a relatively low overall I value even if this disparity in LDH is neglected. This is largely a result of virtually complete differentiation at two other Ldh loci. It is suggested that the large contribution by 3 out of the 4 Ldh loci to population differentiation, may indicate a specific adaptive response by the Venetian population to the unusual conditions of its habitat.