AskDefine | Define taxon

Dictionary Definition

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

User Contributed Dictionary

English

Noun

  1. Any of the taxonomic categories such as phylum or subspecies
  2. A specific taxonomic category above superfamily and below infraorder; a parvorder

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.
taxon in Bulgarian: Таксон
taxon in Catalan: Tàxon
taxon in Czech: Taxon
taxon in Welsh: Tacson
taxon in German: Taxon
taxon in Estonian: Takson
taxon in Spanish: Taxón
taxon in Esperanto: Taksono
taxon in Persian: آرایه (زیست‌شناسی)
taxon in French: Taxon
taxon in Croatian: Takson
taxon in Italian: Taxon
taxon in Hebrew: טקסון
taxon in Lithuanian: Taksonas
taxon in Maltese: Takson
taxon in Dutch: Taxon
taxon in Japanese: タクソン
taxon in Norwegian: Gruppe (biologi)
taxon in Norwegian Nynorsk: Takson
taxon in Narom: Lague
taxon in Polish: Takson
taxon in Portuguese: Táxon
taxon in Russian: Таксон
taxon in Simple English: Taxon
taxon in Slovak: Taxón
taxon in Slovenian: Takson
taxon in Finnish: Taksoni
taxon in Saterfriesisch: Taxon
taxon in Swedish: Taxon
taxon in Turkish: Takson
taxon in Ukrainian: Таксон
taxon in Chinese: 分類單元
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