- taxonomy is understood as a discipline attempting to catalogue all species, to arrange these species in systems of usually hierarchically ordered groups and naming of these groups in accordance with the rules and recommendations of taxonomic nomenclature. Species can basically be classified in a system of broader and broader (i.e. higher and higher) taxa in three ways, i.e. on the basis of similarity, of phylogenetic relatedness or of both similarity and relatedness. Biologists now generally agree that the basis for classification of organisms, i.e. creation and naming of the individual specific taxa, should be the reconstructed phylogenesis of the studied phylogenetic lines. Thus the subjects of phylogenesis and classification of organisms are usually combined. Although phylogenetics, i.e. the study of phylogenesis, and classification of organisms, including the formation of taxa, are very closely related, they are, in fact, two different disciplines. Because each of them has different goals and somewhat different methodical instruments, they can follow somewhat different principles in some areas. Lack of consideration of these aspects is probably the reason for a great many misunderstandings and controversies amongst the proponents of two of the currently most influential areas of taxonomy, phylogenetic taxonomy (i.e. cladistics) and evolutionary taxonomy (i.e. eclectic systematics).

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The classical Darwinian theory of evolution can explain the evolution of adaptive traits only in asexual organisms. The frozen plasticity theory is much more general: It can also explain the origin and evolution of adaptive traits in both asexual and sexual organisms Read more