Abstract

Several species concepts are generally discussed and evaluated. Then the new definition, the pheno-genetic species concept, is developed; it reads: a species is the largest possible, regional evolutionary unit of pheno-genetically equal (in the typical, specific characters), identically reproducing demes. It is separated from sympatric species by a reproductive isolation that guarantees a unique evolution, an evolution different from that of other species and sufficiently uninfluenced, and that is accompanied by another distinctive pheno-genetic gap. It is separated from allopatric species by a distinctive pheno-genetic gap that - in the case of missing reproductive isolation in bisexual forms — allows the conclusion that such an isolation would have developed, if the species had been sympatric with the allopatric species. This definition is applied to several situations of evolution. The effects of the concepts on the classification of lizards are demonstrated by examples.