Binomial nomenclature

Binomial nomenclature (also called binominal nomenclature or binary nomenclature) is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin grammatical forms, although they can be based on words from other languages. Such a name is called a binomial name (which may be shortened to just "binomial"), a binomen or a scientific name; more informally it is also called a Latin name. The first part of the name identifies the genus to which the species belongs; the second part identifies the species within the genus. For example, humans belong to the genus Homo and within this genus to the species Homo sapiens. The introduction of this system of naming species is credited to Linnaeus, effectively beginning with his work Species Plantarum in 1753.[1] Linnaeus called his two-part name a trivial name (nomen triviale) as opposed to the much longer names then used.

The application of binomial nomenclature is now governed by various internationally agreed codes of rules, of which the two most important are the International Code of Zoological Nomenclature (ICZN) for animals and the International Code of Botanical Nomenclature (ICBN) for plants. Although the general principles underlying binomial nomenclature are common to these two codes, there are some differences, both in the terminology they use and in their precise rules.

In modern usage, in writing the first letter of the first part of the name, the genus, is always capitalized, while that of the second part is not, even when derived from a proper noun such as the name of a person or place. Both parts are italicized. Thus the binomial name of the annual phlox is now written as Phlox drummondii.

In scientific works, the "authority" for a binomial name is usually given, at least when it is first mentioned. Thus zoologists will give the name of a particular sea snail species as "Patella vulgata Linnaeus, 1758". The name "Linnaeus" tells the reader who it was that named the species; 1758 is the date of the publication in which the original description can be found, in this case the 10th edition of the book Systema Naturae. (Botanists are not required to give the date).

Contents

History

Prior to the adoption of the modern binomial system of naming species, those who wrote about animals and plants either used their common names in various languages or adopted more-or-less standardized descriptions. In medieval Europe these descriptions were typically in Latin, which was then the language of science. Such "polynomial names" may sometimes look like binomials, but are significantly different. For example, Gerard's herbal describes various kinds of spiderwort: "The first is called phalangium ramosum, Branched Spiderwort; the second, phalangium non ramosum, Unbranched Spiderwort. The other ... is aptly termed phalangium ephemerum virginianum, Soone Fading Spiderwort of Virginia".[2] The Latin phrases are short descriptions, rather than identifying labels. The problem was that as new species were discovered, their descriptions needed to become ever longer in order to distinguish them from existing species. For example, the tomato had the polynomial Solanum caule inermi herbaceo, foliis pinnatis incisis, meaning "the smooth-stemmed herbaceous solanum with incised pinnate leaves".[1]

The Bauhins, in particular Caspar Bauhin (1560–1624), took some important steps towards the binomial system, by pruning the Latin descriptions, in many cases to two words.[3] The adoption by biologists of a system of strictly binomial nomenclature is due to Swedish botanist and physician Carl von Linné, more commonly known by his Latinized name Carolus Linnaeus (1707–1778). It has been said that the spread of two-part names was in some sense an accident.[1] Linnaeus attempted to describe and classify the entire known natural world. He continued to use polynomial names, but in his Species Plantarum (1753) and later in the 10th edition of Systema Naturae (1758), he supplemented these by what he called a "trivial name" (nomen triviale). The Bauhins' genus names were used in many of these, but the descriptive part was always reduced to a single word.

Linnaeus's trivial names introduced an important new idea, namely that the function of a name could simply be to give a species a unique label. This meant that the name did not need be descriptive; for example both parts could be derived from the names of people. Thus Gerard's phalangium ephemerum virginianum became Tradescantia virginiana, where the genus name honoured John Tradescant the younger,[4] an English botanist and gardener.[5] A bird in the parrot family was named Psittacus alexandri, meaning "Alexander's parrot", after Alexander the Great whose armies introduced eastern parakeets to Greece.[6] Linnaeus' trivial names were much easier to remember and use than the parallel polynomial names and eventually replaced them.[1]

Value

The value of the binomial nomenclature system derives primarily from its economy, its widespread use, and the uniqueness and stability of names it generally favors:

Relationship to classification and taxonomy

Nomenclature (including binomial nomenclature) is not the same as classification, although the two are related. Classification is the ordering of items into groups based on similarities and/or differences; in biological classification, species are one of the kinds of item to be classified.[15] In principle, the names given to species could be completely independent of their classification. This is not the case for binomial names, since the first part of a binomial is the name of the genus into which the species is placed. Above the rank of genus, binomial nomenclature and classification are partly independent; for example, a species retains its binomial name if it is moved from one family to another or from one order to another. The independence is only partial since the names of families and other higher taxa are usually based on genera.

Taxonomy includes both nomenclature and classification. Its first stages (sometimes called "alpha taxonomy") are concerned with finding, describing and naming species of living or fossil organisms.[16] Binomial nomenclature is thus an important part of taxonomy as it is the system by which species are named. Taxonomists are also concerned with classification, including its principles, procedures and rules.[17]

Derivation of binomial names

A complete binomial name is always treated grammatically as if it were a phrase in the Latin language (hence the common use of the term "Latin name" for a binomial name). However, the two parts of a binomial name can each be derived from a number of sources, of which Latin is only one. These include:

The first part of the name, which identifies the genus, must be a word which can be treated as a Latin singular noun in the nominative case. It must be unique within each kingdom, but can be repeated between kingdoms. Thus Huia recurvata is an extinct species of plant, found as fossils in Yunnan, China,[25] whereas Huia masonii is a species of frog found in Java, Indonesia.[26]

The second part of the name, which identifies the species within the genus, is also treated grammatically as a Latin word. It can have one of a number of forms.

Whereas the first part of a binomial name must be unique within a kingdom, the second part is quite commonly used in two or more genera (as is shown by examples of hodgsonii above). The full binomial name must be unique within a kingdom.

Codes

From the mid nineteenth century onwards it became ever more apparent that a body of rules was necessary to govern scientific names. In the course of time these became nomenclature codes. The International Code of Zoological Nomenclature (ICZN) governs the naming of animals,[29] the International Code of Botanical Nomenclature (ICBN) that of plants (including fungi and cyanobacteria), and the International Code of Nomenclature of Bacteria (ICNB) that of bacteria (including Archaea). Virus names are governed by the International Committee on Taxonomy of Viruses (ICTV), a taxonomic code, which determines taxa as well as names. These codes differ in certain ways, e.g.:

Unifying the different codes into a single code, the "BioCode", has been suggested, although implementation is not in sight. (There is also a code in development for a different system of classification which does not use ranks, but instead names clades. This is called the PhyloCode.)

Writing binomial names

The binomial names of species are usually typeset in italics; for example, Homo sapiens.[34] Generally the binomial should be printed in a font different from that used in the normal text; for example, "Several more Homo sapiens fossils were discovered." When handwritten, each part of a binomial name should be underlined; for example, Homo sapiens.[35]

The first part of the binomial, the genus name, is always written with an initial capital letter. In current usage, the second part is never written with an initial capital.[36][37] Older sources, particularly botanical works published before the 1950s, use a different convention. If the second part of the name is derived from a proper noun, e.g. the name of a person or place, a capital letter was used. Thus the modern form Berberis darwinii was written as Berberis Darwinii. A capital was also used when the name is formed by two nouns in apposition, e.g. Panthera Leo or Centaurea Cyanus.[38][39]

When used with a common name, the scientific name often follows in parentheses, although this varies with publication.[40] For example "The house sparrow (Passer domesticus) is decreasing in Europe."

The binomial name should generally be written in full. The exception to this is when several species from the same genus are being listed or discussed in the same paper or report, or the same species is mentioned repeatedly; in which case the genus is written in full when it is first used, but may then be abbreviated to an initial (and a period/full stop).[41] For example, a list of members of the genus Canis might be written as "Canis lupus, C. aureus, C. simensis". In rare cases, this abbreviated form has spread to more general use; for example, the bacterium Escherichia coli is often referred to as just E. coli, and Tyrannosaurus rex is perhaps even better known simply as T. rex, these two both often appearing in this form in popular writing even where the full genus name has not already been given.

The abbreviation "sp." is used when the actual specific name cannot or need not be specified. The abbreviation "spp." (plural) indicates "several species". These abbreviations are not italicised (or underlined).[42] For example: "Canis sp." means "an unspecified species of the genus Canis", while "Canis spp." means "two or more species of the genus Canis". (The abbreviations "sp." and "spp." can easily be confused with the abbreviations "ssp." (zoology) or "subsp." (botany), plurals "sspp." or "subspp.", referring to one or more subspecies. See trinomen (zoology) and infraspecific name (botany).)

The abbreviation "cf." is used when the identification is not confirmed.[43] For example "Corvus cf. splendens" indicates "a bird similar to the house crow but not certainly identified as this species".

In some contexts the dagger symbol ("†") may be used before or after the binomial name to indicate that the species is extinct.

Authority

In scholarly texts, at least the first or main use of the binomial name is usually followed by the "authority" – a way of designating the scientist(s) who first published the name. The authority is written in slightly different ways in zoology and botany: under the ICZN the surname is written in full together with the date (usually only the year) of publication, whereas under the ICBN the name is generally abbreviated and the date omitted. Historically, abbreviations were used in zoology too.

When the original name is changed, e.g. the species is moved to a different genus, both Codes use parentheses around the original authority; the ICBN also requires the person who made the change to be given. Some examples:

Other ranks

Binomial nomenclature, as described here, is a system for naming species. Implicitly it includes a system for naming genera, since the first part of the name of the species is a genus name. In a classification system based on ranks there are also ways of naming ranks above the level of genus and below the level of species. Ranks above genus (e.g. family, order, class) receive one part names which are conventionally not written in italics. Thus the house sparrow, Passer domesticus, belongs to the family Passeridae. Family names are normally based on genus names, although the endings used differ between zoology and botany.

Ranks below species receive three part names, conventionally written in italics like the names of species. There are significant differences between the ICZN and the ICBN. In zoology, the only rank below species is subspecies and the name is written simply as three parts. Thus one of the subspecies of the olive-backed pipit is Anthus hodgsoni berezowskii. In botany, there are many ranks below species and although the name itself is written in three parts, a "connecting term" (not part of the name) is needed to show the rank. Thus the American black elder is Sambucus nigra subsp. canadensis; the white-flowered form of the ivy-leaved cyclamen is Cyclamen hederifolium f. albiflorum.

See also

Notes and references

  1. ^ a b c d e Knapp, Sandra, What's in a name? A history of taxonomy : Linnaeus and the birth of modern taxonomy, Natural History Museum, London, http://www.nhm.ac.uk/nature-online/science-of-natural-history/taxonomy-systematics/history-taxonomy/session1/index.html, retrieved 2011-06-17 
  2. ^ Gerrard, John & Johnson, Thomas (2008), Ollivander, Holly & Thomas, Huw, eds., Gerrard's Herbal : A sampling from the 1633 enlarged and amended edition, Velluminous Press, http://velluminous.com/excerpts/GerardsHerbalSamples.epub, retrieved 2011-06-17 
  3. ^ a b Johnson, A.T. & Smith, H.A. (1972), Plant Names Simplified : Their Pronunciation Derivation & Meaning, Buckenhill, Herefordshire: Landsmans Bookshop, ISBN 978-0-900513-04-6 , p. v
  4. ^ Some sources say that both John Tradescant the younger and his father, John Tradescant the elder, were intended by Linnaeus.
  5. ^ Hyam & Pankhurst 1995, p. 502
  6. ^ Jobling, James A. (2010), Helm Dictionary of Scientific Bird Names, London: Christopher Helm, ISBN 978-1-4081-2501-4 
  7. ^ Van Dyke, Fred (2008), "Contemporary Issues of the Species Concept", Conservation biology: foundations, concepts, applications, Springer, p. 86, ISBN 978-1-4020-6890-4, http://books.google.com/books?id=Evh1UD3ZYWcC&lpg=PR6&pg=PA86#v=onepage&q&f=false, retrieved 2011-06-20 
  8. ^ a b Joan C. Stevenson (1991), Dictionary of concepts in physical anthropology, Greenwood Publishing Group, p. 53, ISBN 9780313247569, http://books.google.com/books?id=MvuHGhrr2ocC&lpg=PP1&pg=PA53#v=onepage&q&f=false 
  9. ^ J. Vaun McArthur (2006), "Species Concepts and Speciation", Microbial ecology: an evolutionary approach, Academic Press, p. 36, ISBN 9780123694911, http://books.google.com/books?id=EcxkOMDHgzwC&lpg=PP1&pg=PA36#v=onepage&q&f=false 
  10. ^ a b Peter J. Russell, Stephen L. Wolfe, Paul E. Hertz, & Cecie Starr (2007), "Species Concepts and Speciation", The Linnaean System of Taxonomy, Volume 2, Cengage Learning, p. 493, ISBN 9780495010333, http://books.google.com/books?id=7F9UlGYGr0sC&lpg=PR1&pg=PA493#v=onepage&q&f=false 
  11. ^ "General Principles of Taxonomy", Competition Science Vision (Pratiyogita Darpan Group) 10 (114): 764–767, 2007, http://books.google.com/?id=0-cDAAAAMBAJ#v=onepage&q&f=false, retrieved June 20, 2011. 
  12. ^ Dashwood, Melanie & Mathew, Brian (2005), Hyacinthaceae – little blue bulbs (RHS Plant Trials and Awards, Bulletin Number 11), Royal Horticultural Society, archived from the original on 20 February 2011, http://www.webcitation.org/5wdYF0E05, retrieved 19 February 2011 
  13. ^ Bergmann, H.H. & Schottler, B. (2001), "Tenerife robin Erithacus (rubecula) superbus - a species of its own?", Dutch Birding 23: 140–146 
  14. ^ Patricia Sund. "Taxonomy Explained". Bird Channel.com. http://www.birdchannel.com/bird-exclusives/taxonomy.aspx. Retrieved June 20, 2011. 
  15. ^ Simpson, Michael G. (2006), Plant Systematics, London: Elsevier Academic Press, ISBN 978-0-12-644460-5 , p. 552
  16. ^ Fortey, Richard (2008), Dry Store Room No. 1: The Secret Life of the Natural History Museum, London: Harper Perennial, ISBN 978-0-00-720989-7 
  17. ^ Davis, Peter H. & Heywood, Vernon H. (1965), Principles of Angiosperm Taxonomy, Edinburgh: Oliver & Boyd , p. 8
  18. ^ Hyam, R. & Pankhurst, R.J. (1995), Plants and their names : a concise dictionary, Oxford: Oxford University Press, ISBN 978-0-19-866189-4 , p. 428
  19. ^ Hyam & Pankhurst 1995, p. 182
  20. ^ Oxford English Dictionary (online ed.), Oxford University Press, 2011, http://www.oed.com/view/Entry/35253, retrieved 2011-06-17 . The OED says "Peruvian language" rather than Quechua; see also Amerindian Words in English.
  21. ^ Hyam & Pankhurst 1995, p. 303
  22. ^ Childs, James E.; Paddock, Christopher D. (2003), "The ascendancy of Amblyomma americanum as a vector of pathogens affecting humans in the United States", Annual Review of Entomology 48 (1): 307–337, doi:10.1146/annurev.ento.48.091801.112728, PMID 12414740 
  23. ^ Hyam & Pankhurst 1995, p. 329
  24. ^ Isaak, Mark, Curiosities of Biological Nomenclature: Puns, archived from the original on 2011-06-17, http://www.webcitation.org/5zVVWLPJ5, retrieved 2011-06-17 
  25. ^ Geng, Bao-Yin (1985), "Huia recurvata — A New Plant from Lower Devonian of Southeastern Yunnan China" (in Chinese, with English abstract), Acta Botanica Sinica 27 (4): 419–426, http://en.cnki.com.cn/Article_en/CJFDTOTAL-ZWXB198504013.htm, retrieved 2011-02-07 
  26. ^ Iskandar, D. & Mumpuni, D. (2004), IUCN Red List of Threatened Species : Huia masonii, http://www.iucnredlist.org/search/details.php/58303/all, retrieved 2011-06-19 
  27. ^ Hyam & Pankhurst 1995, p. 334
  28. ^ The neuter ending -us for comparatives is not always observed, as for example in the name Aglaophyton major, which would be expected to be Aglaophyton majus.
  29. ^ International Commission on Zoological Nomenclature (1999), International Code of Zoological Nomenclature online (4th ed.), The International Trust for Zoological Nomenclature, ISBN 978-0-85301-006-7, http://www.nhm.ac.uk/hosted-sites/iczn/code/, retrieved 2011-06-20 
  30. ^ McNeill, J.; Barrie, F.R.; Burdet, H.M. et al., eds. (2006), International code of botanical nomenclature (Vienna Code) adopted by the seventeenth International Botanical Congress, Vienna, Austria, July 2005 (electronic ed.), Vienna: International Association for Plant Taxonomy, http://ibot.sav.sk/icbn/main.htm, retrieved 2011-02-20 , Article 42
  31. ^ Schmidt, Diane (2003), Guide to reference and information sources in the zoological sciences, Westport, Conn.: Libraries Unlimited, ISBN 978-1-56308-977-0 , p. 4
  32. ^ International Commission on Zoological Nomenclature 1999, Chap. 2, Article 5
  33. ^ Sneath, P.H.A. (2003), International Union of Microbiological Societies, archived from the original on 2011-06-20, http://www.webcitation.org/5zZw0QkDI, retrieved 2011-06-20 
  34. ^ "How to Write Scientific Names of Organisms", Competition Science Vision (Assumption University Journal), http://www.journal.au.edu/au_techno/2001/oct2001/howto.pdf, retrieved June 20, 2011. 
  35. ^ Hugh T.W. Tan & Tan Kai-xin. "Understanding and Learning Scientific Names of Species". Successful Learning, Center for Development of Teaching and Learning, National University of Singapore. http://www.cdtl.nus.edu.sg/success/sl43.htm. Retrieved June 20, 2011. 
  36. ^ Silyn-Roberts, Heather (2000), Writing for Science and Engineering: Papers, Presentations and Reports, Oxford; Boston: Butterworth-Heinemann, ISBN 978-0-7506-4636-9 , p. 198
  37. ^ McNeill et al. 2006, Recommendation 60F
  38. ^ Johnson & Smith 1972, p. 23
  39. ^ The modern notation was resisted by some, partly because writing names like Centaurea cyanus can suggest that cyanus is an adjective which should agree with Centaurea, i.e. that the name should be Centaurea cyana, whereas Cyanus is derived from the Greek name for the cornflower. See Gilbert-Carter, H. (1955), Glossary of the British Flora (2nd ed.), Cambridge University Press, OCLC 559413416 , p. xix.
  40. ^ "Writing Guide". Macquarie University. http://www.gse.mq.edu.au/resources/guide/format.htm. Retrieved June 20, 2011. 
  41. ^ "Linnaean Nomenclature of Plants, Animals, & Bacteria", Merriam-Webster's collegiate dictionary, Merriam-Webster, Inc., 2003, p. 22a – 23a, ISBN 9780877798095, http://books.google.com/books?id=TAnheeIPcAEC&lpg=PP1&pg=PP28#v=onepage&q&f=false 
  42. ^ Matthew A. Jenks. "Plant Nomenclature". Department of Horticulture and Landscape Architecture, Purdue University. http://www.hort.purdue.edu/hort/courses/hort217/Nomenclature/description.htm. Retrieved June 20, 2011. 
  43. ^ Chris Clowes. "Taxonomy – A Primer". peripatus.gen.nz. http://www.peripatus.gen.nz/biology/priTaxonomy.html. Retrieved June 20, 2011. 

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