The branch of biology concerned with the classification of organisms. Organisms were formerly grouped into various taxa (singular taxon) on the basis of observable anatomical and morphological structures, but nowadays molecular and genetic information is used increasingly, and classification systems are continually being revised as more information becomes available. Cladistics is an approach to classification based on evolutionary relationships and the assumption that organisms that exhibit ➤homologous structures are derived from a common ancestor and are therefore related by genealogy. An organism is classified according to a hierarchical system as follows:
kingdom, phylum, class, order, family, genus, species.
Intermediate categories such as subphylum or superorder may be used in particularly large groups such as flowering plants, in which the term ‘division’ traditionally replaced phylum. The purpose of taxonomy is basically twofold: to provide a means of ready identification of organisms, and to infer and illustrate evolutionary relationships between them. Classification and the naming of organisms are closely related. All organisms have a binomial Latinized name based on the ➤Linnaean system. ➤➤Appendix table 8.
Related Credo Articles
Introduction Biological taxonomy may seem like a simple science – biologists merely observe similarities among organisms and construct classification
noun 1. the practice or principles of classification generally ○ Any diagnostic task can be aided by a taxonomy of symptoms and a...
The science of biological classification, i.e. the grouping of organisms according to their natural affinities. (cf. SYSTEMATICS .) A...