DNA barcoding of non-indigenous fish species in the Volga-Kama basin: assessment of current taxonomic assignment and differentiation in the Ponto-Caspian Basin

DNA identification results for certain alien fish species in the Volga-Kama basin are presented. We have revealed different genetic structures among these alien species, which reflect the varying histories of their appearance in the Volga and Kama basins. The observed genetic differentiation of some species is likely related to isolation during transgression and degradation of the Pontic Lake-Sea in the post-Miocene period. The current stage of faunal mixing is associated with the dispersal of hydrobionts beyond their historical ranges through corridors newly formed as a result of human activities. The use of DNA barcoding helped to elucidate the genetic structure of po pulations of several fish species alien to the Volga and Kama. In general, our results did not confirm the advisability of excessively splitting species into the “Azov-Black Sea” and “Caspian” taxa.