ABSTRACT
The Darwinian theory of evolution is based upon two propositions: first, that there is random variation within species and, secondly, that the forces of natural selection have the power to order the randomness by actively favouring the most advantageous variants (i.e., the most fit). As a consequence of ecological, geographical and/or reproductive isolation, this process may lead to speciation and, ultimately, to the evolution of higher taxa. Evolution is, therefore, initiated at and below the rank of species, higher taxa being the products of more ancient evolutionary events.
