Echoes from the past: a genetic trace of native brown trout in the Italian Alps

Mitochondrial dloop and nuclear tnfa II sequences were sequenced from brown trout collected in the Vesta River (Italian Alps), situated in the middle of a Pleistocene ice free refugia area east of the Lake Garda. Haplotypes belonging to the native Adriatic lineage were mixed with other from the Atlantic and Marble lineages. A probabilistic approach, based on simulations, indicated the likelihood of a past introgression of Atlantic haplotypes into native populations belonging to the Adriatic lineage. These results argue in favor of a past natural presence of brown trout in the Italian Alps, in particular in ice free refugia areas, which have been almost completely wiped out by the massive and extensive introduction of Atlantic hatchery stocks.