The Center of Origin and Colonization Routes of Noble Salmons of the Genus Salmo (Salmonidae, Actinopterigii)

Fresh- and Brackish-Water Cold-Tolerant Species of Southern Europe: Migrants from the Paratethys That Colonized the Arctic

“…However, a study of the mitochondrial COI gene diversity of noble salmons throughout almost the entire range of the genus Salmo was recently carried out. Median-joining haplotype network analysis entirely confirmed the opinion of Dorofeeva [22]: the most ancient haplotype of the brown trout was found in the population of the Aral Sea basin, but it also occurred in the basins of the Caspian and Adriatic seas [76].…”

“…Our study of the mitochondrial COI gene diversity has demonstrated that the brown trout populations of the Black and Caspian seas are characterized by different groups of haplotypes, whereas the Mediterranean populations of this species have the haplotypes found in the Caspian basin (or those directly originating from them). In turn, the haplotypes similar to those that are common in the Black Sea basin are found only in a few populations of the northern coast of the Mediterranean Sea, i.e., the haplotypes of the Black Sea group are not characteristic of this region [76].…”

“…The migration of cold-water species from the Black Sea basin to the Mediterranean apparently occurred much later and on a limited scale. In particular, the mollusk Ecrobia maritima, typical of the Black Sea [112], and individuals of brown trout carrying the mitochondrial DNA haplotypes typical of the Black Sea basin [76] are quite rare in the Mediterranean basin.…”

“…The Balkan Peninsula, which is rich in cold water bodies, including the karstic ones, proved to be the most favorable habitat for the cold-water invaders in the Mediterranean [19]. Some cold-tolerant taxa occur only in the Balkan Peninsula (the nine-spined sticklebacks and the lamprey Eudontomyzon hellenicus); furthermore, the most ancient haplotypes of some aquatic taxa widespread in the Mediterranean region (the noble salmon and three-spined sticklebacks) are found in this area [49,64,76,135].…”

“…Although the Paratethys lost its direct connection with the Atlantic and Arctic oceans in the Upper Miocene [17], aquatic animals may have sometimes migrated from the Paratethys to the basins of these oceans as a result of rare events of watershed interception caused by geological processes, primarily of orogenic nature (Figure 1, arrow 4). Apparently, this is how the carriers of one of the haplotypes characteristic of the Black Sea brown trout invaded the Rhine basin, the upper reaches of which were then part of a vast water system, now narrowed to the Danube basin [76]. Probably, the European pearl mussel migrated to the Rhine basin from the area of the present-day Black Sea basin together with the brown trout.…”