title: Species concept and taxonomic principles.
abstract: Based on the species concept of changing versus unchanging, the present work deals with the following two problems: First, why would the taxonomic system reflect evolutionary history? Second, how is this effected? Species are changing in the sense that each species has its own characteristics and there is no complete identity between any two species. On the other hand, species are unchanging and each one conserves a set of ancestral characters which allocates its taxonomic position, and this is the reason why the taxonomic system reflects evolutionary history. The taxonomic system is constructed to reflect evolutionary history mainly through the process of character analysis. Combining the viewpoints of cladistics and evolutionary systematics, the writer proposes six rules for character analysis which will provide the basis for analyzing evolutionary history.
mesh_terms: D000818:Animals; D005075:Biological Evolution; D002965:Classification; D006801:Humans; D008954:Models, Biological