Khác biệt giữa bản sửa đổi của “Bậc phân loại”
Nội dung được xóa Nội dung được thêm vào
n →Nghiên cứu thêm: General Fixes |
Không có tóm lược sửa đổi |
||
Dòng 1:
[[File:Taxonomic Rank Graph.svg|right|thumb|550px|This graph shows the main '''taxonomic ranks''': domain, kingdom, phylum, class, order, family, genus, and species. Here it demonstrates how taxonomic ranking is used to classify animals and earlier life forms related to the red fox, [[Vulpes vulpes]].<ref>http://www.123rf.com /clipart-vector/vulpes_vulpes.html</ref>]]
{{Biological classification}}
In [[biological classification]], '''rank''' is the relative level of an organism or groups of organisms in a [[Taxonomy (biology)|taxonomic]] [[hierarchy]]. Examples of taxonomic ranks are [[species]], [[genus]], [[family (biology)|family]], [[class (biology)|class]], [[kingdom (biology)|kingdom]], etc.
A given rank subsumes under it less general categories, that is, more specific descriptions of life forms. Above it, each rank is classified within more general categories of organisms and groups of organisms related to each other through inheritance of traits or features from common ancestors. The rank of any ''species'' and the description of its ''genus'' is ''basic''; which means that to identify a particular organism, it is usually not necessary to specify ranks other than these first two.<ref>[http://www.iapt-taxon.org/nomen/main.php?page=art2 International Code of Nomenclature for algae, fungi, and plants, Melbourne Code, 2012, articles 2 and 3]</ref>
Consider the foxes; and one of theirs, the red fox ''[[Vulpes vulpes]]'': its next rank, the genus ''[[Vulpes]]'', comprises all the 'true foxes'. Their closest relatives are in the immediately higher rank, the family [[Canidae]], which includes dogs, wolves, jackals, all foxes, and other [[caniforms]]; the next higher rank, the order [[Carnivora]], includes feliforms and caniforms (lions, and tigers, and bears; and hyenas, wolverines, and all those mentioned above), plus other carnivorous [[mammals]]. As one group of the class [[Mammalia]], all the above are classified among those with backbones in the rank [[Chordata]], and with them among all the [[animals]] in the kingdom rank. And all the above will find their earliest relatives somewhere among the [[Eukarya]] in the domain rank.
The ''[[International Code of Zoological Nomenclature]]'' defines rank as:
:The level, for nomenclatural purposes, of a [[taxon]] in a taxonomic hierarchy (e.g. all families are for nomenclatural purposes at the same rank, which lies between superfamily and subfamily)<ref>{{citation |author=International Commission on Zoological Nomenclature |year=1999 |title=International Code of Zoological Nomenclature. Fourth Edition |publisher=International Trust for Zoological Nomenclature |url=http://iczn.org/iczn/index.jsp}}</ref>
== Main ranks ==
In his landmark publications, such as the ''[[Systema Naturae]]'', [[Carolus Linnaeus]] used a ranking scale limited to: kingdom, class, order, genus, species, and one rank below species. Today, nomenclature is regulated by the [[nomenclature codes]]. There are seven main taxonomic ranks: kingdom, phylum or division, class, order, family, genus, species. In addition, the ''domain'' (proposed by [[Carl Woese]]) is now widely used as one of the fundamental ranks, although it is not mentioned in any of the nomenclature codes.
{| class="wikitable" style="margin: 0 auto;"
|colspan=4 align="center" bgcolor="#C1CDC1" | '''Main taxonomic ranks'''
|-
|colspan=2 align="center" style="width:160px;" bgcolor="#E0EEE0" | Latin
|colspan=2 align="center" style="width:160px;" bgcolor="#E0EEE0" | English
|-
|colspan=2 | ''regio''
|colspan=2 | [[domain (biology)|domain]]
|-
|colspan=2 | ''regnum''
|colspan=2 | [[kingdom (biology)|kingdom]]
|-
||''phylum''||''divisio''
||[[phylum]]<sup> (in [[zoology]])</sup>||[[division (biology)|division]]<sup> (in [[botany]])</sup>
|-
|colspan=2 | ''classis''
|colspan=2 | [[class (biology)|class]]
|-
|colspan=2 | ''ordo''
|colspan=2 | [[order (biology)|order]]
|-
|colspan=2 | ''familia''
|colspan=2 | [[family (biology)|family]]
|-
|colspan=2 | ''genus''
|colspan=2 | [[genus]]
|-
|colspan=2 | ''species''
|colspan=2 | [[species]]
|}
A taxon is usually assigned a rank when it is given its formal name. The basic ranks are species and genus. When an organism is given a species name it is assigned to a genus, and the genus name is part of the species name.
The species name is also called a [[binomial nomenclature|binomial]], that is, a two-term name. For example, the zoological name for the human species is ''Homo sapiens''. This is usually italicized in print and underlined when italics are not available. In this case, ''Homo'' is the generic name and it is capitalized; ''sapiens'' indicates the species and it is not capitalized.
==Ranks in zoology==
There are definitions of the following taxonomic ranks in the [[International Code of Zoological Nomenclature]]: superfamily, family, subfamily, tribe, subtribe, genus, subgenus, species, subspecies.
The International Code of Zoological Nomenclature divides names into "family-group names", "genus-group names" and "species-group names". The Code explicitly mentions:
----
:Superfamily
''[[Family (biology)|Family]]''
:[[Subfamily]]
:[[Tribe (biology)|Tribe]]
:[[Subtribe]]
----
''[[Genus]]''
:[[Subgenus]]
----
''[[Species]]''
:[[Subspecies]]
----
The rules in the Code apply to the ranks of superfamily to subspecies, and only to some extent to those above the rank of superfamily. In the "genus group" and "species group" no further ranks are allowed. Among zoologists, additional terms such as ''species group'', ''species subgroup'', ''species complex'' and ''superspecies'' are sometimes used for convenience as extra, but unofficial, ranks between the subgenus and species levels in [[taxa]] with many species (e.g. the genus ''[[Drosophila]]'').
At higher ranks (family and above) a lower level may be denoted by adding the prefix "''infra''", meaning ''lower'', to the rank. For example ''infra''order (below suborder) or ''infra''family (below subfamily).
===Names of zoological taxa===
* A taxon above the rank of species has a scientific name in one part (a uninominal name).
* A species has a name composed of two parts (a binomial name or [[binomen]]): [[name of a biological genus|generic name]] + [[specific name (zoology)|specific name]]; for example ''Canis lupus''.
* A subspecies has a name composed of three parts (a trinomial name or [[trinomen]]): generic name + specific name + [[subspecific name]]; for example ''Canis lupus familiaris''. As there is only one possible rank below that of species, no connecting term to indicate rank is needed or used.
==Ranks in botany==
According to Art 3.1 of the [[International Code of Nomenclature for algae, fungi, and plants]] (ICN) the most important ranks of taxa are: kingdom, division or phylum, class, order, family, genus, and species. According to Art 4.1 the secondary ranks of taxa are tribe, section, series, variety and form. There is an indeterminate number of ranks. The ICN explicitly mentions:<ref>[http://www.iapt-taxon.org/nomen/main.php?page=art3 International Code of Nomenclature for algae, fungi, and plants, Melbourne Code, 2012, articles 3 and 4]</ref>
----
'''''primary ranks'''''
:'''''secondary ranks'''''
::'''''further ranks'''''
----
'''''kingdom''''' (''regnum'')
::''subregnum''
'''''division''''' or '''phylum''' (''divisio'', ''phylum'')
::''subdivisio'' or ''subphylum''
'''''class''''' (''classis'')
::''subclassis''
'''''order''''' (''ordo'')
::''subordo''
----
'''''family''''' (''familia'')
::''subfamilia''
:'''tribe''' (''tribus'')
::''subtribus''
'''''genus''''' (''genus'')
::''subgenus''
:'''section''' (''sectio'')
::''subsection''
:'''series''' (''series'')
::''subseries''
'''''species''''' (''species'')
::''subspecies''
:'''variety''' (''varietas'')
::''subvarietas''
:'''form''' (''forma'')
::''subforma''
----
There are definitions of the following taxonomic categories in the [[International Code of Nomenclature for Cultivated Plants]]: [[cultivar group]], [[cultivar]], [[Grex (horticulture)|grex]].
The rules in the ICN apply primarily to the ranks of family and below, and only to some extent to those above the rank of family. Also see [[descriptive botanical names]].
===Names of botanical taxa===<!-- [[Nothotaxon]] redirects here -->
Of the botanical ranks used by [[Carolus Linnaeus|Linnaeus]] only names of genera, species and varieties are still used.
Taxa at the rank of genus and above have a [[botanical name]] in one part (unitary name); those at the rank of species and above (but below genus) have a botanical name in two parts ([[binary name]]); all taxa below the rank of species have a botanical name in three parts (an [[Infraspecific name (botany)|infraspecific name]]). To indicate the rank of the infraspecific name, a "connecting term" is needed. Thus ''Poa secunda'' subsp. ''juncifolia'', where "subsp." is an abbreviation for "subspecies", is the name of a subspecies of ''[[Poa secunda]]''.
Hybrids can be specified either by a "hybrid formula" that specifies the parentage, or may be given a name. For hybrids getting a [[hybrid name]], the same ranks apply, prefixed with ''notho'' (Greek: "bastard"), with nothogenus as the highest permitted rank.
==== Outdated names for botanical ranks ====
If a different term for the rank was used in an old publication, but the intention is clear, botanical nomenclature specifies certain substitutions:
* If names were "intended as names of orders, but published with their rank denoted by a term such as": "cohors" [Latin for "cohort"<ref>Stearn, W.T. 1992. ''Botanical Latin: History, grammar, syntax, terminology and vocabulary, Fourth edition''. David and Charles.</ref>], "nixus", "alliance", or "Reihe" instead of "order" (Article 17.2), they are treated as names of orders.
* "Family" is substituted for "order" (ordo) or "natural order" (ordo naturalis) under certain conditions where the modern meaning of "order" was not intended. (Article 18.2)
* "Subfamily is substituted for "suborder" (subordo) under certain conditions where the modern meaning of "suborder" was not intended. (Article 19.2)
* In a publication prior to 1 January 1890, if only one infraspecific rank is used, it is considered to be that of variety. (Article 35.4) This commonly applies to publications that labelled infraspecific taxa with Greek letters, α, β, γ, ...
==Examples==
Classifications of five species follow: the [[Drosophila melanogaster|fruit fly]] so familiar in genetics laboratories (''Drosophila melanogaster''), [[human]]s (''Homo sapiens''), the [[pea]]s used by [[Gregor Mendel]] in his discovery of [[genetics]] (''Pisum sativum''), the "fly agaric" mushroom ''[[Amanita muscaria]]'', and the bacterium ''[[Escherichia coli]]''. The eight major ranks are given in bold; a selection of minor ranks are given as well.
{| border="1" cellpadding="4" cellspacing="0" style="margin: 0.5em 1em 0.5em 0; background: #f9f9f9; border: 1px #aaa solid; border-collapse: collapse;"
|- style="background:palegrey; border: 1px;"
!style="width:16%; background:#f3f3f3;"|Rank
!style="width:16%; background:#f3f3f3;"|[[Drosophila melanogaster|Fruit fly]]
!style="width:16%; background:#f3f3f3;"|[[Human]]
!style="width:16%; background:#f3f3f3;"|[[Pea]]
!style="width:16%; background:#f3f3f3;"|[[Amanita muscaria|Fly agaric]]
!style="width:16%; background:#f3f3f3;"|''[[Escherichia coli|E. coli]]''
|-
|style="background:#f2f2f2;"|'''[[Domain (biology)|Domain]]'''
|[[Eukaryote|Eukarya]]
|[[Eukaryote|Eukarya]]
|[[Eukaryote|Eukarya]]
|[[Eukaryote|Eukarya]]
|[[Bacteria]]
|-
|style="background:#f2f2f2;"|'''[[Kingdom (biology)|Kingdom]]'''
|[[Animal]]ia
|[[Animal]]ia
|[[Plant]]ae
|[[Fungus|Fungi]]
|[[Bacteria]]
|-
|style="background:#f2f2f2;"|'''[[Phylum]]''' or '''[[Division (biology)|Division]]'''
|[[Arthropod]]a
|[[Chordate|Chordata]]
|[[Flowering plant|Magnoliophyta]]
|[[Basidiomycota]]
|[[Proteobacteria]]
|-
|style="background:#f2f2f2;"|[[Subphylum]] or subdivision
|[[Hexapoda]]
|[[Vertebrate|Vertebrata]]
|Magnoliophytina
|[[Agaricomycotina]]
|
|-
|style="background:#f2f2f2;"|'''[[Class (biology)|Class]]'''
|[[Insect]]a
|[[Mammal]]ia
|[[Magnoliopsida]]
|[[Agaricomycetes]]
|[[Gammaproteobacteria]]
|-
|style="background:#f2f2f2;"|Subclass
|[[Pterygota]]
|[[Theria]]
|[[Rosidae]]
|[[Agaricomycetidae]]
|
|-
|style="background:#f2f2f2;"|'''[[Order (biology)|Order]]'''
|[[Fly|Diptera]]
|[[Primate]]s
|[[Fabales]]
|[[Agaricales]]
|[[Enterobacteriaceae|Enterobacteriales]]
|-
|style="background:#f2f2f2;"|Suborder
|[[Brachycera]]
|[[Haplorrhini]]
|Fabineae
|Agaricineae
|
|-
|style="background:#f2f2f2;"|'''[[Family (biology)|Family]]'''
|[[Drosophilidae]]
|[[Great ape|Hominidae]]
|[[Fabaceae]]
|[[Amanitaceae]]
|[[Enterobacteriaceae]]
|-
|style="background:#f2f2f2;"|Subfamily
|[[Drosophilinae]]
|[[Homininae]]
|[[Faboideae]]
|[[Amanitoideae]]
|
|-
|style="background:#f2f2f2;"|'''[[Genus]]'''
|''[[Drosophila]]''
|''[[Homo (genus)|Homo]]''
|''[[Pisum]]''
|''[[Amanita]]''
|''[[Escherichia]]''
|-
|style="background:#f2f2f2;"|'''[[Species]]'''
|''[[Drosophila melanogaster|D. melanogaster]]''
|''[[Human|H. sapiens]]''
|''[[Pea|P. sativum]]''
|''[[Amanita muscaria|A. muscaria]]''
|''[[Escherichia coli|E. coli]]''
|}
;Table notes:
*The ranks of higher taxa, especially intermediate ranks, are prone to revision as new information about relationships is discovered. For example, the traditional classification of primates (class Mammalia — subclass Theria — infraclass Eutheria — order Primates) has been modified by new classifications such as McKenna and Bell (class Mammalia — subclass Theriformes — infraclass Holotheria) with Theria and Eutheria assigned lower ranks between infraclass and the order Primates. See [[mammal classification]] for a discussion. These differences arise because there are only a small number of ranks available and a large number of branching points in the fossil record.
*Within species further units may be recognised. Animals may be classified into subspecies (for example, ''Homo sapiens sapiens'', modern humans) or [[Polymorphism (biology)|morph]]s (for example ''Corvus corax varius'' morpha ''leucophaeus'', the Pied Raven). Plants may be classified into subspecies (for example, ''Pisum sativum'' subsp. ''sativum'', the garden pea) or varieties (for example, ''Pisum sativum'' var. ''macrocarpon'', snow pea), with cultivated plants getting a [[cultivar]] name (for example, ''Pisum sativum'' var. ''macrocarpon'' 'Snowbird'). Bacteria may be classified by [[strain (biology)|strains]] (for example [[Escherichia coli O157:H7|''Escherichia coli'' O157:H7]], a strain that can cause [[Foodborne illness|food poisoning]]).
*[[Mnemonic]]s are available at [http://www.mnemonic-device.eu/biology mnemonic-device.eu] and [http://acronyms.thefreedictionary.com/KPCOFGS thefreedictionary.com].
==Terminations of names==
[[Taxon|Taxa]] above the genus level are often given names based on the [[type genus]], with a standard termination. The terminations used in forming these names depend on the kingdom (and sometimes the phylum and class) as set out in the table below.
Pronunciations given are the [[Traditional English pronunciation of Latin|most Anglicized]]. More Latinate pronunciations are also common, particularly {{IPAc-en|ɑː}} rather than {{IPAc-en|eɪ}} for stressed ''a''.
{| border="1" align="center" cellpadding="4" cellspacing="0" style="margin: 0.5em 1em 0.5em 0; background: #f9f9f9; border: 1px #aaa solid; border-collapse: collapse;"
|-
!style="background:#f3f3f3;"|Rank
!style="background:#f3f3f3;"|[[Bacteria]]<ref>[http://www.bacterio.cict.fr/classificationgenera.html Bacteriologocal Code (1990 Revision)]</ref>
!style="background:#f3f3f3;"|[[Plant]]s
!style="background:#f3f3f3;"|[[Algae]]
!style="background:#f3f3f3;"|[[Fungus|Fungi]]
!style="background:#f3f3f3;"|[[Animal]]s
|-
|style="background:#f2f2f2;"|'''Division/Phylum'''
|
| -phyta {{IPAc-en|ˈ|f|aɪ|t|ə}}
| -phycota {{IPAc-en|ˈ|f|aɪ|k|oʊ|t|ə}}
| -mycota {{IPAc-en|m|aɪ|ˈ|k|oʊ|t|ə}}
|
|-
|style="background:#f2f2f2;"|'''Subdivision/Subphylum'''
|
| -phytina {{IPAc-en|f|ɨ|ˈ|t|aɪ|n|ə}}
| -phycotina {{IPAc-en|f|ɨ|k|ɵ|ˈ|t|aɪ|n|ə}}
| -mycotina {{IPAc-en|m|aɪ|k|ɵ|ˈ|t|aɪ|n|ə}}
|
|-
|style="background:#f2f2f2;"|'''Class'''
| -ia {{IPAc-en|i|ə}}
| -opsida {{IPAc-en|ˈ|ɒ|p|s|ɨ|d|ə}}
| -phyceae {{IPAc-en|ˈ|f|aɪ|ʃ|iː}}
| -mycetes {{IPAc-en|m|aɪ|ˈ|s|iː|t|iː|z}}
|
|-
|style="background:#f2f2f2;"|'''Subclass'''
|align="center" colspan=2| -{{Not a typo|idae}} {{IPAc-en|ɨ|d|iː}}
| -phycidae {{IPAc-en|ˈ|f|ɪ|s|ɨ|d|iː}}
| -mycetidae {{IPAc-en|m|aɪ|ˈ|s|ɛ|t|ɨ|d|iː}}
|
|-
|style="background:#f2f2f2;"|'''Superorder'''
|
|align="center" colspan=3| -anae {{IPAc-en|ˈ|eɪ|n|iː}}
|
|-
|style="background:#f2f2f2;"|'''Order'''
|align="center" colspan=4| -ales {{IPAc-en|ˈ|eɪ|l|iː|z}}
|-
|style="background:#f2f2f2;"|'''Suborder'''
|align="center" colspan=4| -ineae {{IPAc-en|ˈ|ɪ|n|ɨ|.|iː}}
|
|-
|style="background:#f2f2f2;"|'''Infraorder'''
|
|align="center" colspan=3| -aria {{IPAc-en|ˈ|ɛər|i|.|ə}}
|
|-
|style="background:#f2f2f2;"|'''Superfamily'''
|
|align="center" colspan=3| -acea {{IPAc-en|ˈ|eɪ|ʃ|ə}}
| -oidea {{IPAc-en|ˈ|ɔɪ|d|i|.|ə}}
|-
|style="background:#f2f2f2;"|'''Epifamily'''
|
|
|
|
| -oidae {{IPAc-en|ˈ|ɔɪ|d|iː}}
|-
|style="background:#f2f2f2;"|'''Family'''
|align="center" colspan=4| -aceae {{IPAc-en|ˈ|eɪ|ʃ|iː}}
| -{{Not a typo|idae}} {{IPAc-en|ɨ|d|iː}}
|-
|style="background:#f2f2f2;"|'''Subfamily'''
|align="center" colspan=4| -oideae {{IPAc-en|ˈ|ɔɪ|d|ɨ|.|iː}}
| -inae {{IPAc-en|ˈ|aɪ|n|iː}}
|-
|style="background:#f2f2f2;"|'''Infrafamily'''
|
|
|
|
| -odd {{IPAc-en|ɒ|d}}<ref>For example, the [[Testudines|chelonia]]n infrafamilies Chelodd (Gaffney & Meylan 1988: 169) and Baenodd (''ibid.'', 176).</ref>
|-
|style="background:#f2f2f2;"|'''Tribe'''
|align="center" colspan=4| -eae {{IPAc-en|ɨ|.|iː}}
| -ini {{IPAc-en|ˈ|aɪ|n|aɪ}}
|-
|style="background:#f2f2f2;"|'''Subtribe'''
|align="center" colspan=4| -inae {{IPAc-en|ˈ|aɪ|n|iː}}
| -ina {{IPAc-en|ˈ|aɪ|n|ə}}
|-
|style="background:#f2f2f2;"|'''Infratribe'''
|
|
|
|
| -ad {{IPAc-en|æ|d}} or -iti {{IPAc-en|ˈ|aɪ|t|i}}
|}
;Table notes:
* In botany and mycology names at the rank of family and below are based on the name of a genus, sometimes called the [[type genus]] of that taxon, with a standard ending. For example, the rose family [[Rosaceae]] is named after the genus ''Rosa'', with the standard ending "-aceae" for a family. Names above the rank of family are also formed from a generic name, or are descriptive (like [[Gymnosperm]]ae or [[Fungus|Fungi]]).
* For animals, there are standard suffixes for taxa only up to the rank of superfamily.<ref>ICZN article 29.2</ref>
* Forming a name based on a generic name may be not straightforward. For example, the [[Latin]] "''homo''" has the genitive "''hominis''", thus the genus "''Homo''" (human) is in the [[Great ape|Hominidae]], not "Homidae".
* The ranks of epifamily, infrafamily and infratribe (in animals) are used where the complexities of phyletic branching require finer-than-usual distinctions. Although they fall below the rank of superfamily, they are not regulated under the International Code of Zoological Nomenclature and hence do not have formal standard endings. The suffixes listed here are regular, but informal.<ref>As supplied by Gaffney & Meylan (1988).</ref>
==All ranks==
There is an indeterminate number of ranks, as a taxonomist may invent a new rank at will, at any time, if they feel this is necessary. In doing so, there are some restrictions, which will vary with the [[Nomenclature codes|nomenclature code]] which applies.
The following is an artificial synthesis, solely for purposes of demonstration of relative rank (but see notes), from most general to most specific:<ref>For the general usage and coordination of zoological ranks between the phylum and family levels, including many intercalary ranks, see Carroll (1988). For additional intercalary ranks in zoology, see especially Gaffney & Meylan (1988); McKenna & Bell (1997); Milner (1988); Novacek (1986, cit. in Carroll 1988: 499, 629); and [[Paul Sereno]]'s 1986 classification of [[ornithischia]]n dinosaurs as reported in Lambert (1990: 149, 159). For botanical ranks, including many intercalary ranks, see Willis & McElwain (2002).</ref>
* '''[[Domain (biology)|Domain]]''' ''or'' '''Empire'''
** '''[[Kingdom (biology)|Kingdom]]'''
*** [[Subkingdom]]
**** Infrakingdom
* [[Superphylum]] (''or'' Superdivision ''in botany'')
** '''[[Phylum (biology)|Phylum]]''' (''or'' '''[[Division (biology)|Division]]''' ''in botany'')
*** [[Subphylum]] (''or'' Subdivision ''in botany'')
**** [[Infraphylum]] (''or'' Infradivision ''in botany'')
***** [[Microphylum]]
* [[Class (biology)|Superclass]]
** '''[[Class (biology)|Class]]'''
*** [[Class (biology)|Subclass]]
**** [[Infraclass]]
***** [[Parvclass]]
* Superdivision (''zoology'')<ref name="divisionzool"/>
** [[Division (biology)|Division]] (''zoology'')<ref name="divisionzool">These are movable ranks, most often inserted between the class and the legion or cohort. Nevertheless, their positioning in the zoological hierarchy may be subject to wide variation. For examples, see the [http://palaeo.gly.bris.ac.uk/benton/vertclass.html Benton classification of vertebrates] (2005).</ref>
*** Subdivision (''zoology'')<ref name="divisionzool"/>
**** Infradivision (''zoology'')<ref name="divisionzool"/>
* Superlegion (''zoology'')
** [[Legion (biology)|Legion]] (''zoology'')
*** Sublegion (''zoology'')
**** Infralegion (''zoology'')
* Supercohort (''zoology'')<ref name="cohort">In zoological classification, the cohort and its associated group of ranks are inserted between the class group and the ordinal group. The cohort has also been used between infraorder and family in [[saurischia]]n dinosaurs ([http://palaeo.gly.bris.ac.uk/benton/vertclass.html Benton] 2005). In botanical classification, the cohort group has sometimes been inserted between the division (phylum) group and the class group: see Willis & McElwain (2002: 100–101), or has sometimes been used at the rank of order, and is now considered to be an obsolete name for order: See International Code of Nomenclature for algae, fungi, and plants, Melbourne Code 2012, Article 17.2.</ref>
** Cohort (''zoology'')<ref name="cohort"/>
*** Subcohort (''zoology'')<ref name="cohort"/>
**** Infracohort (''zoology'')<ref name="cohort"/>
* Gigaorder (''zoology'')<ref name="ordinal"/>
** [[Magnorder]] ''or'' Megaorder (''zoology'')<ref name="ordinal">The supra-ordinal sequence gigaorder-megaorder-capaxorder-hyperorder (and the microorder, in roughly the position most often assigned to the parvorder) has been employed in turtles at least (Gaffney & Meylan 1988), while the parallel sequence magnorder-grandorder-mirorder figures in recently influential classifications of mammals. It is unclear from the sources how these two sequences are to be coordinated (or interwoven) within a unitary zoological hierarchy of ranks. Previously, Novacek (1986) and McKenna-Bell (1997) had inserted mirorders and grandorders between the order and superorder, but Benton (2005) now positions both of these ranks above the superorder.</ref>
*** Grandorder ''or'' Capaxorder (''zoology'')<ref name="ordinal"/>
**** Mirorder ''or'' Hyperorder (''zoology'')<ref name="ordinal"/>
***** [[Superorder]]
****** Series (''for fish'')
******* '''[[Order (biology)|Order]]'''
******** [[Parvorder]] (''position in some zoological classifications'')
********* Nanorder (''zoology'')
********** Hypoorder (''zoology'')
*********** Minorder (''zoology'')
************ [[Suborder]]
************* [[Infraorder]]
************** [[Parvorder]] (''usual position'') ''or'' Microorder (''zoology'')<ref name="ordinal"/>
* Section (''zoology'')
** Subsection (''zoology'')
* Gigafamily (''zoology'')
** Megafamily (''zoology'')
*** Grandfamily (''zoology'')
**** Hyperfamily (''zoology'')
***** Superfamily
****** Epifamily (''zoology'')
******* Series (''for Lepidoptera'')
******** Group (''for Lepidoptera'')
********* '''[[Family (biology)|Family]]'''
********** [[Subfamily]]
*********** Infrafamily
* Supertribe
** [[Tribe (biology)|Tribe]]
*** [[Subtribe]]
**** Infratribe
* '''[[Genus]]'''
** [[Subgenus]]
*** [[Section (botany)|Section (''botany'')]]
**** Subsection (''botany'')
***** [[Series (biology)|Series (''botany'')]]
****** Subseries (''botany'')
* [[Superspecies]] ''or'' [[Cryptic species complex|Species-group]]
** '''[[Species]]'''
*** [[Subspecies]] (''or'' Forma Specialis ''for fungi, or'' Variety ''for bacteria''<ref>Additionally, the terms [[biovar]], [[morphovar]] and [[serovar]] designate bacterial [[strain (biology)|strain]]s (genetic variants) that are physiologically or biochemically distinctive. These are not taxonomic ranks, but are groupings of various sorts which may define a bacterial subspecies.</ref>)
**** [[Variety (botany)|Variety]] (''botany'') or [[Form (zoology)|Form]]/[[Morph (zoology)|Morph]] (''zoology'')
***** [[Subvariety]] (''botany'')
****** [[Form (botany)|Form]] (''botany'')
******* Subform (''botany'')
== Significance and problems ==
Ranks are assigned based on subjective dissimilarity, and do not fully reflect the gradational nature of variation within nature. In most cases, higher taxonomic groupings arise further back in time: not because the rate of diversification was higher in the past, but because each subsequent diversification event results in an increase of diversity and thus increases the taxonomic rank assigned by present-day taxonomists.<ref name="Gingerich1987">{{cite doi|10.1139/z87-169 }}</ref>
Of these many ranks, the most basic is species. However, this is not to say that a taxon at any other rank may not be sharply defined, or that any species is guaranteed to be sharply defined. It varies from case to case. Ideally, a taxon is intended to represent a [[clade]], that is, the [[phylogenetics|phylogeny]] of the organisms under discussion, but this is not a requirement.{{Citation needed|date=August 2011}}
Classification, in which all taxa have formal ranks, cannot adequately reflect our knowledge about phylogeny; at the same time, if taxon names are dependent on ranks, rank-free taxa can't be supplied with names. This problem is dissolved in cladoendesis, where the specially elaborated rank-free nomenclatures are used.<ref>Kluge N.J. 1999. A system of alternative nomenclatures of supra-species taxa. Linnaean and post-Linnaean principles of systematics. // Entomological Review 79(2): 133-147</ref><ref>Kluge N.J. 2010. Circumscriptional names of higher taxa in Hexapoda. // Bionomina 1: 15–55</ref>
==See also==
* [[Breed]]
* [[Catalogue of Life]]
* [[Cladistics]]
* [[Landrace]]
== Hình ảnh ==
| |||