The Hierarchy of Organisms: Systematics and Classification in Biology

Traditionally, classifications in biology were based on typological judgement. Current classifications frequently maintain many groups and assume relationships which are still based on simple typology. Approaches of ‘transformed cladistics’ are close to advanced methods of numerical phenetics; decisions are not primarily based on evolutionary thinking. For such reasons, the method of phylogenetic systematics is regarded as the valid approach in biological classification. It includes tools for the reconstruction of the historical process of phylogenetic branching. In a secondary step, the results obtained are directly transposed into a classification (system) which qualifies as a scientific hypothesis. Phylogenetic systematics permits only one ‘correct’ classification as there has been only one course in phylogeny.