classification
classification The arrangement of organisms into a series of groups based on physiological, biochemical, anatomical, or other relationships. An artificial classification is based on one or a few characters simply for ease of identification or for a specific purpose; for example, birds are often arranged according to habit and habitat (seabirds, songbirds, birds of prey, etc.) while fungi may be classified as edible or poisonous. Such systems do not reflect evolutionary relationships. A natural classification is based on resemblances and is a hierarchical arrangement. The smallest group commonly used is the species. Species are grouped into genera (see genus), the hierarchy continuing up through tribes, families, orders, classes, and phyla (see phylum) to kingdoms and, in some systems, to domains. In traditional systems of plant classification the phylum was replaced by the division. Higher up in the hierarchy the similarities between members of a group become fewer. Present-day natural classifications try to take into account as many features as possible and in so doing aim to reflect evolutionary relationships (see cladistics). Natural classifications are also predictive. Thus if an organism is placed in a particular genus because it shows certain features characteristic of the genus, then it can be assumed it is very likely to possess most (if not all) of the other features of that genus. See also binomial nomenclature; taxonomy.
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classification