Mitochondrial phylogeography of the killifish Aphanius fasciatus (Teleostei, Cyprinodontidae) reveals highly divergent Mediterranean populations

We studied the genetic structure of the Mediterranean killifish Aphanius fasciatus. Analysis of the sequence variation in a 372-bp portion of the mitochondrial control region in 623 fish from 27 sampling sites alongthe species’ distributional range (Tyrrhenian coast, Sardinia, Sicily, Adriatic coast, Malta, Tunisia, and Greece) yielded 120 distinct haplotypes. Most of the haplotypes areunique, and only 15 % are shared among different populations.The high FST value (=0.80) suggests a strong population genetic structuring. The phylogenetic analysis basedon Bayesian inference, maximum likelihood and maximumparsimony, and the median-joining network show a sharp separation of the Southeastern Sicilian populations(belonging to the Hyblean region) and of the fluvial Tunisian population of Rio Melah from the others. The Adriatic, the Eastern Sicilian, and the Greek populations are well differentiated, while the group of populations from the Central-Western Mediterranean does not show a clearpattern of differentiation. Our findings indicate that the current genetic structuring of A. fasciatus reflects historical geographical patterns occurring within the Mediterraneanbasin from the Late Miocene to the Pleistocene. The presence of divergent evolutionary entities in the Hyblean region and the Tunisian Rio Melah supports their inclusion as target areas for the conservation of A. fasciatus.