RESUMO
Genetic diversity and colonization routes of noble salmons were studied using a partial nucleotide sequence of the mitochondrial COI gene. The brown trout S. trutta, which is the most ancient species of the genus, was concluded to originate from the modern southeastern Pontic-Caspian area, which is currently inhabited by members of the subspecies S. trutta oxianus. Migrating westward while the Paratethys was in existence (5-34 million years ago), species of the genus colonized ancient water bodies in the modern Mediterranean basin and formed many isolated populations that survived desiccation of the Mediterranean Sea (5-6 million years ago). The Strait of Gibraltar mediated brown trout migrations to Northern Europe; the subspecies S. trutta trutta belongs to a relatively young phylogenetic lineage of the species. A separate brown trout lineage, currently classified as the subspecies S. trutta labrax, formed most likely in the area of the modern Danube basin, which was a relatively separate part of the Paratethys and was sometimes isolated as the Pannonian Lake. A highly divergent phylogenetic lineage of Atlantic salmon (S. salar) haplotypes originates from a haplotype of the brown trout that inhabited the area of the modern Strait of Gibraltar.
