Phylogenetic Models and Classification

Several statements are suggested as necessary for the fomiulation of any theory of phylogeny reconstruction; these include statements about kinship relationships, the origination and diversification of taxonomic units, and clustering. From these basic statements an attempt is made to construct phylogenetic models corresponding to the theory and methods of the two principle schools of systematic thought. The models are compared, and it is concluded that the phylogenetic systematic model is a more powerful tool in reconstructing phylogeny than is the evolutionary systematic model. The ways in which the phylogenetic models influence the form and content of classifications are discussed. Only information about phylogenetic (cladistic)relationships can be stored in and retrieved from Linnaean hierarchical classifications, and thus classifications should be based on a phylogenetic systematic model because such a classification will reproduce precisely the information (phylogeny) used to construct it.