Molecular markers, phylogeography and search for the criteria for delimiting species

Abstract

The search for practical criteria for delimiting species was always topical. The waves of species splitting and lumping always altered depending both from dominant species concept, fashion and methods applied. Starting from the end of the last century the description of species diversity is at the peak of splitting wave. The specific feature of current splitting wave is that it relies 1) on new wide array of characters – molecular markers with their universality and easy application; 2) wide application of molecular markers in its turn gave birth to new methodology – phylogenetic analysis penetrates to intraspecies level, new direction of studies – phylogeography (Avise et al., 1987) appears and explosively develops. Phylogeography very successfully fall on phylogenetic species concept using gene trees as the basis for delimiting species and this «tree-thinking» approach together with widely expanding studies on phylogeography lead to dramatic increase in species number practically in all groups of vertebrates. Unlike morphological characters, molecular markers are universal (occur in all or almost in all organisms) and genetic distances, therewith, at a first glance gave an universal metrics for delimiting species which could be applied to almost all groups. Thus remarkable and long-awaited perspective opens- systematics receive an universal tool for distinguishing and delimitation of species. However, this hope on universal criteria once again appeared to be false and all issues which rise while working with molecular markers are very similar to those one have using morphological approach. In other words application of molecular markers bring us back to old and well known issues major part of which currently has no solution and the feeling that biologists at last have gain a unit similar to exact sciences is very wrong.