AskDefine | Define taxa

Dictionary Definition

taxon n : animal or plant group having natural relations [syn: taxonomic group, taxonomic category] [also: taxa (pl)]taxa See taxon

User Contributed Dictionary

English

Noun

taxa
  1. Plural of taxon

French

Verb

  1. Form of Third-person singular past historic, taxer

Extensive Definition

A taxon (plural taxa), or taxonomic unit, is a name designating an organism or a group of organisms. In biological nomenclature according to Carl Linnaeus, a taxon is assigned a taxonomic rank and can be placed at a particular level in a systematic hierarchy reflecting evolutionary relationships.
A distinction is to be made between taxa/taxonomy and classification/systematics. The former refers to biological names and the rules of naming. The latter refers to rank ordering of taxa according to presumptive evolutionary (phylogenetic) relationships.
Note: "Phylum" applies formally to any biological domain, but traditionally it was always used for animals, whereas "Division" was traditionally often used for plants, fungi, etc.
A simple mnemonic phrase to remember the sequence of taxonomic levels is: "Dignified Kings Play Chess On Fine Green Silk"; another, highly expedient example is "King Philip's Class Orders the Family Genius to Speak".
A prefix is used to indicate a ranking of lesser importance. The prefix super- indicates a rank above, the prefix sub- indicates a rank below. In zoology the prefix infra- indicates a rank below sub-. For instance:
Superclass
Class
Subclass
Infraclass
Rank is relative, and restricted to a particular systematic schema. For example, liverworts have been grouped, in various systems of classification, as a family, order, class, or division (phylum). The use of a narrow set of ranks is challenged by users of cladistics; for example, the mere 10 ranks traditionally used between animal families (governed by the ICZN) and animal phyla (usually the highest relevant rank in taxonomic work) often cannot adequately represent the evolutionary history as more about a lineage's phylogeny becomes known. In addition, the class rank is quite often not an evolutionary but a phenetical and paraphyletic group and as opposed to those ranks governed by the ICZN, can usually not be made monophyletic by exchanging the taxa contained therein. This has given rise to phylogenetic taxonomy and the ongoing development of the PhyloCode, which is to govern the application of taxa to clades.
taxa in Bulgarian: Таксон
taxa in Catalan: Tàxon
taxa in Czech: Taxon
taxa in Welsh: Tacson
taxa in German: Taxon
taxa in Estonian: Takson
taxa in Spanish: Taxón
taxa in Esperanto: Taksono
taxa in Persian: آرایه (زیست‌شناسی)
taxa in French: Taxon
taxa in Croatian: Takson
taxa in Italian: Taxon
taxa in Hebrew: טקסון
taxa in Lithuanian: Taksonas
taxa in Maltese: Takson
taxa in Dutch: Taxon
taxa in Japanese: タクソン
taxa in Norwegian: Gruppe (biologi)
taxa in Norwegian Nynorsk: Takson
taxa in Narom: Lague
taxa in Polish: Takson
taxa in Portuguese: Táxon
taxa in Russian: Таксон
taxa in Simple English: Taxon
taxa in Slovak: Taxón
taxa in Slovenian: Takson
taxa in Finnish: Taksoni
taxa in Saterfriesisch: Taxon
taxa in Swedish: Taxon
taxa in Turkish: Takson
taxa in Ukrainian: Таксон
taxa in Chinese: 分類單元
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