MARKED MITOCHONDRIAL-DNA DIFFERENCES BETW EEN MEDITERRANEAN AND EASTERN ATLANTIC POPULATIONS OF THE ROUND SARDINELLA, SARDINELLA-AURITA

Digestion by restriction enzymes has been carried out on polymerase ch ain reaction products of the mitochondrial DNA control region of round sardine (Sardinella aurita) samples coming from the Eastern Atlantic and the Mediterranean Sea. The results show i) that though the habitat is continuous, there is no gene flow between the two basins where two genetically differentiated groups can be recognized ii) that each bas in is genetically homogeneous and, iii) that the haplotypic diversity in the Mediterranean is between two and three times smaller than that observed in the Atlantic. These results can hardly be explained by a r ecent colonization from the Eastern Atlantic. This suggests that, for S. aurita and some other species, the Mediterranean Sea is genetically little influenced by the Eastern Atlantic.