Division (biology)

Division is a taxonomic rank in biological classification that is used differently in zoology and in botany.

In botany and mycology, division refers to a rank equivalent to phylum. The use of either term is allowed under the International Code of Botanical Nomenclature,^[1] and both are commonly used in scientific literature.

The main Divisions of land plants are the Marchantiophyta (liverworts), Anthocerotophyta (hornworts), Bryophyta (mosses), Filicophyta (ferns), Sphenophyta (horsetails), Cycadophyta (cycads), Ginkgophyta (ginkgo)s, Pinophyta (conifers), Gnetophyta (gnetophytes), and the Magnoliophyta (Angiosperms, flowering plants). The Magnoliophyta now dominate terrestrial ecosystems, comprising 80% of vascular plant species.^[2]

In zoology, the term division is applied to an optional rank subordinate to the infraclass and superordinate to the cohort. A widely used classification (e.g. Carroll 1988^[3]) recognises teleost fishes as a Division Teleostei within Class Actinopterygii (the ray-finned fishes). Less commonly (as in Milner 1988^[4]), 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 eukaryotes, where heterotrophic organisms were classified under zoological nomenclature (using "phylum") while autotrophic organisms fell under botanical nomenclature (using "division"). Their proposal to standardise the terminology aimed to reflect the growing scientific appreciation for the unity of all organisms. 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.^[5]

Molecular phylogenetic classification

The use of 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.^[6]

References

^ McNeill, J.; et al., eds. (2012). International Code of Nomenclature for algae, fungi, and plants (Melbourne Code), Adopted by the Eighteenth International Botanical Congress Melbourne, Australia, July 2011 (electronic ed.). International Association for Plant Taxonomy. Retrieved 2017-05-14.
^ Judd, Walter S.; Campbell, Christopher S.; Kellogg, Elizabeth A.; Stevens, Peter F.; Donoghue, Michael J. (2002). Plant systematics, a phylogenetic approach (2nd ed.). Sunderland MA, USA: Sinauer Associates Inc. ISBN 0-87893-403-0.
^ (Carroll 1988)
^ (Milner 1988)
^ Bold, H.C.; Cronquist, A.; Jeffey, C.; Johnson, L.A.S.; Marguilis, L.; Merximiller, H.; Takhtajan, A.L. (1978). "Proposa (10) to substitute the term phylum for division for groups treated as plants" (PDF). Taxon. 27 (1): 121–122.
^ Woese, C.R.; Stackebrandt, E.; Macke, T.J.; Fox, G.E. (1985). "A phylogenetic definition of the major eubacterial taxa". Systematic and Applied Microbiology. 6 (2): 143–151. doi:10.1016/S0723-2020(85)80047-3.

Works cited

Carroll, Robert L. (1988), Vertebrate Paleontology and Evolution, New York: W.H. Freeman & Co., ISBN 0-716-7-1822-7
Milner, Andrew (1988), "The relationships and origin of living amphibians", in M.J. Benton (ed.), 'The Phylogeny and Classification of the Tetrapods, vol. 1: Amphibians, Reptiles, Birds, Oxford: Clarendon Press, pp. 59–102

This biology article is a stub. You can help Wikipedia by expanding it.

[ICN-1] McNeill, J.; et al., eds. (2012). International Code of Nomenclature for algae, fungi, and plants (Melbourne Code), Adopted by the Eighteenth International Botanical Congress Melbourne, Australia, July 2011 (electronic ed.). International Association for Plant Taxonomy. Retrieved 2017-05-14.

[Judd-2] Judd, Walter S.; Campbell, Christopher S.; Kellogg, Elizabeth A.; Stevens, Peter F.; Donoghue, Michael J. (2002). Plant systematics, a phylogenetic approach (2nd ed.). Sunderland MA, USA: Sinauer Associates Inc. ISBN 0-87893-403-0.

[3] (Carroll 1988)

[4] (Milner 1988)

[Bold_et_al._1978-5] Bold, H.C.; Cronquist, A.; Jeffey, C.; Johnson, L.A.S.; Marguilis, L.; Merximiller, H.; Takhtajan, A.L. (1978). "Proposa (10) to substitute the term phylum for division for groups treated as plants" (PDF). Taxon. 27 (1): 121–122.

[Woese_et_al._1985-6] Woese, C.R.; Stackebrandt, E.; Macke, T.J.; Fox, G.E. (1985). "A phylogenetic definition of the major eubacterial taxa". Systematic and Applied Microbiology. 6 (2): 143–151. doi:10.1016/S0723-2020(85)80047-3.

[1]

[2]

[3]

[4]

[5]

[6]