Editing Division (taxonomy)

{{Short description|Taxonomic rank equivalent to phylum in botanical classification}}
{{About|categorisations of organisms|division of invidual cells|cell division}}
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'''Division''' is a [[taxonomic rank]] in [[biological classification]] that is used differently in zoology and in botany.

In [[botany]] and [[mycology]], ''division'' is the traditional name for a rank now considered equivalent to [[phylum]]. The use of either term is allowed under the [[International Code of Botanical Nomenclature]].<ref name="ICN">{{Cite book |year=2012 |editor-last=McNeill |editor-first=J. |display-editors=etal|title=International Code of Nomenclature for algae, fungi, and plants (Melbourne Code), Adopted by the Eighteenth International Botanical Congress Melbourne, Australia, July 2011 |edition=electronic |publisher=International Association for Plant Taxonomy |url=http://www.iapt-taxon.org/nomen/main.php?page=art3 |accessdate=2017-05-14 }}</ref>

The main Divisions of [[Embryophyte|land plants]] are the [[Marchantiophyta]] (liverworts), [[Anthocerotophyta]] (hornworts), [[Moss|Bryophyta]] (mosses), [[Filicophyta]] (ferns), [[Sphenophyta]] (horsetails), [[Cycadophyta]] (cycads), [[Ginkgophyta]] (ginkgo)s, [[Pinophyta]] (conifers), [[Gnetophyta]] (gnetophytes), and the [[flowering plant|Magnoliophyta]] (Angiosperms, flowering plants). The Magnoliophyta now dominate terrestrial [[ecosystem]]s, comprising 80% of [[vascular plant]] species.<ref name=Judd>{{cite book |first1=Walter S.|last1=Judd|first2=Christopher S.|last2=Campbell |first3=Elizabeth A. |last3=Kellogg |first4=Peter F. |last4=Stevens |first5=Michael J. |last5=Donoghue |title=Plant systematics, a phylogenetic approach |edition=2nd |date=2002 |publisher=Sinauer Associates Inc. |location=Sunderland MA, USA |isbn=0-87893-403-0 }}</ref>

In [[zoology]], the term ''division'' is applied to an optional rank subordinate to the [[infraclass]] and superordinate to the [[Legion (taxonomy)|legion]] and [[cohort (taxonomy)|cohort]]. A widely used classification (e.g. Carroll 1988<ref>{{harv|Carroll 1988|ref=Carroll}}</ref>) recognises [[teleost]] fishes as a Division Teleostei within Class [[Actinopterygii]] (the ray-finned fishes). Less commonly (as in Milner 1988<ref>{{harv| Milner 1988|ref=Milner}}</ref>), living [[tetrapods]] are ranked as Divisions [[Amphibia]] and [[Amniota]] within the [[clade]] of vertebrates with fleshy limbs ([[Sarcopterygii]]).

==Proposals for standardisation==

In 1978, a group of botanists including [[Harold Charles Bold]], [[Arthur Cronquist]] and [[Lynn Margulis]] proposed replacing the term "division" with "phylum" in botanical nomenclature, arguing that maintaining different terms for the same taxonomic rank across biological kingdoms created unnecessary confusion. This was particularly problematic for unicellular [[eukaryote]]s, where [[heterotrophic]] organisms were classified under zoological nomenclature (using "phylum") while [[autotrophic]] organisms fell under botanical nomenclature (using "division"). They proposed updating the International Code of Botanical Nomenclature to use "phylum" and "subphylum" throughout, while maintaining that names originally published as divisions would be treated as if they had been published as phyla.<ref name="Bold et al. 1978"/>

==Molecular phylogenetic classification==

The use of [[molecular phylogenetics|molecular]] methods, particularly [[16S ribosomal RNA]] analysis, helped establish major bacterial divisions in the 1980s. In 1985, [[Carl Woese]] and colleagues identified ten major groups of eubacteria through [[oligonucleotide]] signature analysis, noting that these groupings were "appropriately termed eubacterial Phyla or Divisions." This work provided early molecular evidence for the equivalence of bacterial divisions with phyla and helped establish a [[phylogenetic]] basis for high-level bacterial classification.<ref name="Woese et al. 1985"/>

==Viruses and prokaryotes==

In 2020, the [[International Committee on Taxonomy of Viruses]] (ICTV) formalised a 15-rank hierarchical classification system, ranging from the highest rank "[[realm (virology)|realm]]" (rather than [[Domain (biology)|domain]]) down through the lower ranks, notably using "phylum" rather than "division". Under this system, the first viral realm established was ''[[Riboviria]]'', encompassing all [[RNA virus]]es that encode an [[RNA-directed RNA polymerase]].<ref name="ICTV 2000"/>

In 2021, the [[International Code of Nomenclature of Prokaryotes]] (ICNP) formally included the rank of phylum for the first time, adopting the [[suffix]] "-ota" for phylum names. This led to the publication of names for 46 prokaryotic phyla with [[microbiological culture|cultured]] representatives, replacing some established names with [[neologism]]s – for example, "[[Proteobacteria]]" became "[[Pseudomonadota]]" and "[[Firmicutes]]" became "[[Bacillota]]".<ref name="Pallen 2024"/>

==References==
{{reflist|refs=

<ref name="Bold et al. 1978">{{cite journal |last1=Bold |first1=H.C. |last2=Cronquist |first2=A. |last3=Jeffey |first3=C. |last4=Johnson |first4=L.A.S. |last5=Marguilis |first5=L. |last6=Merximiller |first6=H. |last7=Takhtajan |first7=A.L. |year=1978 |title=Proposa (10) to substitute the term phylum for division for groups treated as plants |journal=Taxon |volume=27 |issue=1 |pages=121–122 |url=https://www.iapt-taxon.org/historic/Congress/IBC_1981/Prop009-010.pdf}}</ref>

<ref name="ICTV 2000">{{cite journal |author=International Committee on Taxonomy of Viruses Executive Committee |last2=Gorbalenya |first2=Alexander E. |last3=Krupovic |first3=Mart |last4=Mushegian |first4=Arcady |last5=Kropinski |first5=Andrew M. |last6=Siddell |first6=Stuart G. |last7=Varsani |first7=Arvind |last8=Adams |first8=Michael J. |last9=Davison |first9=Andrew J. |last10=Dutilh |first10=Bas E. |last11=Harrach |first11=Balázs |last12=Harrison |first12=Robert L. |last13=Junglen |first13=Sandra |last14=King |first14=Andrew M. Q. |last15=Knowles |first15=Nick J. |last16=Lefkowitz |first16=Elliot J. |last17=Nibert |first17=Max L. |last18=Rubino |first18=Luisa |last19=Sabanadzovic |first19=Sead |last20=Sanfaçon |first20=Hélène |last21=Simmonds |first21=Peter |last22=Walker |first22=Peter J. |last23=Zerbini |first23=F. Murilo |last24=Kuhn |first24=Jens H. |title=The new scope of virus taxonomy: partitioning the virosphere into 15 hierarchical ranks |journal=Nature Microbiology |volume=5 |issue=5 |year=2020 |pmid=32341570 |pmc=7186216 |doi=10.1038/s41564-020-0709-x |doi-access=free |pages=668–674}}</ref>

<ref name="Pallen 2024">{{cite journal |last=Pallen |first=Mark J. |title=The dynamic history of prokaryotic phyla: discovery, diversity and division |journal=International Journal of Systematic and Evolutionary Microbiology |volume=74 |issue=9 |year=2024 |pmid=39250184 |pmc=11382960 |doi=10.1099/ijsem.0.006508 |page=e006508|pmc-embargo-date=September 9, 2025 }}</ref>

<ref name="Woese et al. 1985">{{cite journal |last1=Woese |first1=C.R. |last2=Stackebrandt |first2=E. |last3=Macke |first3=T.J. |last4=Fox |first4=G.E. |title=A phylogenetic definition of the major eubacterial taxa |journal=Systematic and Applied Microbiology |volume=6 |issue=2 |year=1985 |doi=10.1016/S0723-2020(85)80047-3 |pages=143–151|pmid=11542017 |bibcode=1985SyApM...6..143W }}</ref>

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===Works cited===
*{{citation |author=Carroll, Robert L. |year=1988 |title=Vertebrate Paleontology and Evolution |publisher=New York: W.H. Freeman & Co. |isbn=0-716-7-1822-7 |ref=Carroll |url-access=registration |url=https://archive.org/details/vertebratepaleon0000carr }}
*{{citation |author=Milner, Andrew |year=1988 |chapter=The relationships and origin of living amphibians |editor=M.J. Benton |title='The Phylogeny and Classification of the Tetrapods |volume=1: Amphibians, Reptiles, Birds |pages=59–102 |publisher=Oxford: Clarendon Press |ref=Milner}}

{{Taxonomic ranks}}

[[Category:Scientific classification]]
[[Category:Botanical nomenclature]]