The genetic species concept and its versatility

Abstract

A review of the species criteria of the four most popular species concepts (typological, genetic, bio-logical, and evolutionary-phylogenetic) shows that they are essentially the same. In each of them, the fact of fixing alternative alleles in diverging populations is a key circumstance in one form or another. Such groups of populations should be considered as a kind of evolutionary genetic dis-creteness supported by a protected gene pool. Therefore, a biological species should be understood as a set of populations, individuals of which have the fixation of common unique alleles for a num-ber of structural genes. Differences between the concepts are secondary and are due to the emphasis on different sides of the same phenomenon or the use of different methods for determining the ge-netic structure. It is indicated that there are subjective difficulties in the application of the genetic concept (the reluctance of traditional taxonomists to lose their monopoly) and objective problems caused by the unequal period of divergence of taxa of the species rank and different ways of form-ing genetically discrete entities.