Genetic structure of the killifish Aphanius fasciatus, Nardo 1827 (Teleostei, Cyprinodontidae), results of mitochondrial DNA analysis

Aphanius fasciatus is a cyprinodont distributed in the salty coastal water of the central and eastern Mediterranean Sea and occasionally in internal fresh water. In this work, the authors have investigated the genetic structure of eight populations of the killifish A. fasciatus from Sardinia and Sicily. The comparison of the mtDNA control region of 237 individuals revealed a total of 49 haplotypes. Several unique haplotypes were present in each population, and no common haplotype was found among Sicilian and Sardinian populations. Almost all Sardinian populations shared a common haplotype, and indeed the four Sicilian populations examined did not share any as determined by the parsimony network analysis. The analysis of molecular variance showed that the percentage of variation among populations is much higher than within each population of A. fasciatus. The overall FST value is very high (0·78) and supports an extensive genetic structure of the populations. The observed genetic differentiations of A. fasciatus populations were discussed taking into account the palaeogeographic and palaeoclimatic events that interested the Mediterranean area from Miocenic to Pleistocenic age. The results provide new insight into the knowledge of the pattern of genetic structure and of evolutionary processes occurring in this species.