|Part of a series on|
With advances in the theory, data and analytical technology of biological systematics, the Linnaean system has transformed into a system of modern biological classification intended to reflect the evolutionary relationships among organisms, both living and extinct.
The exact definition of taxonomy varies from source to source, but the core of the discipline remains: the conception, naming, and classification of groups of organisms. As points of reference, recent definitions of taxonomy are presented below:
- Theory and practice of grouping individuals into species, arranging species into larger groups, and giving those groups names, thus producing a classification.
- A field of science (and major component of systematics) that encompasses description, identification, nomenclature, and classification
- The science of classification, in biology the arrangement of organisms into a classification
- "The science of classification as applied to living organisms, including the study of means of formation of species, etc."
- "The analysis of an organism's characteristics for the purpose of classification"
- "Systematics studies phylogeny to provide a pattern that can be translated into the classification and names of the more inclusive field of taxonomy" (listed as a desirable but unusual definition)
The varied definitions either place taxonomy as a sub-area of systematics (definition 2), invert that relationship (definition 6), or appear to consider the two terms synonymous. There is some disagreement as to whether
- Systematics: "The study of the identification, taxonomy, and nomenclature of organisms, including the classification of living things with regard to their natural relationships and the study of variation and the evolution of taxa".
In 1970 Michener et al. defined "systematic biology" and "taxonomy" (terms that are often confused and used interchangeably) in relationship to one another as follows:
Systematic biology (hereafter called simply systematics) is the field that (a) provides scientific names for organisms, (b) describes them, (c) preserves collections of them, (d) provides classifications for the organisms, keys for their identification, and data on their distributions, (e) investigates their evolutionary histories, and (f) considers their environmental adaptations. This is a field with a long history that in recent years has experienced a notable renaissance, principally with respect to theoretical content. Part of the theoretical material has to do with evolutionary areas (topics e and f above), the rest relates especially to the problem of classification. Taxonomy is that part of Systematics concerned with topics (a) to (d) above.
A whole set of terms including taxonomy, systematic biology, systematics, biosystematics, scientific classification, biological classification, and
Monograph and taxonomic revision
A taxonomic revision or taxonomic review is a novel analysis of the variation patterns in a particular taxon. This analysis may be executed on the basis of any combination of the various available kinds of characters, such as morphological, anatomical, palynological, biochemical and genetic. A monograph or complete revision is a revision that is comprehensive for a taxon for the information given at a particular time, and for the entire world. Other (partial) revisions may be restricted in the sense that they may only use some of the available character sets or have a limited spatial scope. A revision results in a conformation of or new insights in the relationships between the subtaxa within the taxon under study, which may lead to a change in the classification of these subtaxa, the identification of new subtaxa, or the merger of previous subtaxa.
Taxonomic characters are the taxonomic attributes that can be used to provide the evidence from which relationships (the
- Morphological characters
- Physiological characters
- Metabolic factors
- Body secretions
- Genic sterility factors
- Molecular characters
- Immunological distance
- Electrophoretic differences
- Amino acid sequences of proteins
- DNA hybridization
- DNA and RNA sequences
- Restriction endonuclease analyses
- Other molecular differences
- Behavioral characters
- Courtship and other ethological isolating mechanisms
- Other behavior patterns
- Ecological characters
- Habit and habitats
- Seasonal variations
- Parasites and hosts
- Geographic characters
Alpha and beta taxonomy
The term "alpha taxonomy" is primarily used today to refer to the discipline of finding, describing, and naming taxa, particularly species. In earlier literature, the term had a different meaning, referring to morphological taxonomy, and the products of research through the end of the 19th century.
William Bertram Turrill introduced the term "alpha taxonomy" in a series of papers published in 1935 and 1937 in which he discussed the philosophy and possible future directions of the discipline of taxonomy.
... there is an increasing desire amongst taxonomists to consider their problems from wider viewpoints, to investigate the possibilities of closer co-operation with their cytological, ecological and genetics colleagues and to acknowledge that some revision or expansion, perhaps of a drastic nature, of their aims and methods, may be desirable ... Turrill (1935) has suggested that while accepting the older invaluable taxonomy, based on structure, and conveniently designated "alpha", it is possible to glimpse a far-distant taxonomy built upon as wide a basis of morphological and physiological facts as possible, and one in which "place is found for all observational and experimental data relating, even if indirectly, to the constitution, subdivision, origin, and behaviour of species and other taxonomic groups". Ideals can, it may be said, never be completely realized. They have, however, a great value of acting as permanent stimulants, and if we have some, even vague, ideal of an "omega" taxonomy we may progress a little way down the Greek alphabet. Some of us please ourselves by thinking we are now groping in a "beta" taxonomy.
Turrill thus explicitly excludes from alpha taxonomy various areas of study that he includes within taxonomy as a whole, such as ecology, physiology, genetics, and cytology. He further excludes phylogenetic reconstruction from alpha taxonomy.
Later authors have used the term in a different sense, to mean the delimitation of species (not subspecies or taxa of other ranks), using whatever investigative techniques are available, and including sophisticated computational or laboratory techniques. Thus, Ernst Mayr in 1968 defined "beta taxonomy" as the classification of ranks higher than species.
An understanding of the biological meaning of variation and of the evolutionary origin of groups of related species is even more important for the second stage of taxonomic activity, the sorting of species into groups of relatives ("taxa") and their arrangement in a hierarchy of higher categories. This activity is what the term classification denotes; it is also referred to as "beta taxonomy".
Microtaxonomy and macrotaxonomy
How species should be defined in a particular group of organisms gives rise to practical and theoretical problems that are referred to as the
While some descriptions of taxonomic history attempt to date taxonomy to ancient civilizations, a truly scientific attempt to classify organisms did not occur until the 18th century. Earlier works were primarily descriptive and focused on plants that were useful in agriculture or medicine. There are a number of stages in this scientific thinking. Early taxonomy was based on arbitrary criteria, the so-called "artificial systems", including
Naming and classifying human surroundings likely begun with the onset of language. Distinguishing poisonous plants from edible plants is integral to the survival of human communities. Medicinal plant illustrations show up in Egyptian wall paintings from c. 1500 BC, indicating that the uses of different species were understood and that a basic taxonomy was in place.
Organisms were first classified by
Taxonomy in the
Renaissance and early modern
During the Renaissance and the Age of Enlightenment, categorizing organisms became more prevalent, and taxonomic works became ambitious enough to replace the ancient texts. This is sometimes credited to the development of sophisticated optical lenses, which allowed the morphology of organisms to be studied in much greater detail. One of the earliest authors to take advantage of this leap in technology was the Italian physician Andrea Cesalpino (1519–1603), who has been called "the first taxonomist". His magnum opus De Plantis came out in 1583, and described more than 1500 plant species. Two large plant families that he first recognized are still in use today: the Asteraceae and Brassicaceae. Then in the 17th century John Ray (England, 1627–1705) wrote many important taxonomic works. Arguably his greatest accomplishment was Methodus Plantarum Nova (1682), in which he published details of over 18,000 plant species. At the time, his classifications were perhaps the most complex yet produced by any taxonomist, as he based his taxa on many combined characters. The next major taxonomic works were produced by Joseph Pitton de Tournefort (France, 1656–1708). His work from 1700, Institutiones Rei Herbariae, included more than 9000 species in 698 genera, which directly influenced Linnaeus, as it was the text he used as a young student.
The Swedish botanist
Modern system of classification
A pattern of groups nested within groups was specified by Linnaeus' classifications of plants and animals, and these patterns began to be represented as
With Darwin's theory, a general acceptance quickly appeared that a classification should reflect the Darwinian principle of
Cladistic classifications are compatible with traditional Linnean taxonomy and the Codes of
Kingdoms and domains
Well before discovery of Carl Linnaeus (Botanist) plants and animals were considered separate Kingdoms.[unreliable source?] Linnaeus used this as the top rank, dividing the physical world into the vegetable, animal and mineral kingdoms. As advances in microscopy made the classification of microorganisms possible, the number of kingdoms increased, five- and six-kingdom systems being the most common.
|Woese et al.
|2 kingdoms||3 kingdoms||2 empires||4 kingdoms||5 kingdoms||3 domains||2 empires, 6 kingdoms||2 empires, 7 kingdoms|
Recent comprehensive classifications
Partial classifications exist for many individual groups of organisms and are revised and replaced as new information becomes available; however, comprehensive, published treatments of most or all life are rarer; recent examples are that of Adl et al., 2012 and 2019,
Biological taxonomy is a sub-discipline of biology, and is generally practiced by biologists known as "taxonomists", though enthusiastic naturalists are also frequently involved in the publication of new taxa. Because taxonomy aims to describe and organize life, the work conducted by taxonomists is essential for the study of biodiversity and the resulting field of conservation biology.
Biological classification is a critical component of the taxonomic process. As a result, it informs the user as to what the relatives of the taxon are hypothesized to be. Biological classification uses taxonomic ranks, including among others (in order from most inclusive to least inclusive): Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species, and Strain.[note 1]
The "definition" of a taxon is encapsulated by its description or its diagnosis or by both combined. There are no set rules governing the definition of taxa, but the naming and publication of new taxa is governed by sets of rules.
The initial description of a taxon involves five main requirements:
- The taxon must be given a name based on the 26 letters of the Latin alphabet (a binomial for new species, or uninomial for other ranks).
- The name must be unique (i.e. not a homonym).
- The description must be based on at least one name-bearing type specimen.
- It should include statements about appropriate attributes either to describe (define) the taxon or to differentiate it from other taxa (the diagnosis, ICZN Code, Article 13.1.1, ICN, Article 38, which may or may not be based on morphology). Both codes deliberately separate defining the content of a taxon (its circumscription) from defining its name.
- These first four requirements must be published in a work that is obtainable in numerous identical copies, as a permanent scientific record.
However, often much more information is included, like the geographic range of the taxon, ecological notes, chemistry, behavior, etc. How researchers arrive at their taxa varies: depending on the available data, and resources, methods vary from simple
An "authority" may be placed after a scientific name.
In phenetics, also known as taximetrics, or numerical taxonomy, organisms are classified based on overall similarity, regardless of their phylogeny or evolutionary relationships.
Modern taxonomy uses database technologies to search and catalogue classifications and their documentation. While there is no commonly used database, there are comprehensive databases such as the Catalogue of Life, which attempts to list every documented species. The catalogue listed 1.64 million species for all kingdoms as of April 2016, claiming coverage of more than three quarters of the estimated species known to modern science.
- Automated species identification
- Bacterial taxonomy
- Cluster analysis
- Consortium for the Barcode of Life
- Consortium of European Taxonomic Facilities
- Glossary of scientific naming
- Identification (biology)
- Incertae sedis
- Open Tree of Life
- Set theory
- Taxonomy (general)
- Virus classification
- This ranking system, except for "Strain," can be remembered by the mnemonic "Do Kings Play Chess On Fine Glass Sets?"
- Wilkins, J.S. (5 February 2011). "What is systematics and what is taxonomy?". Archived from the original on 27 August 2016. Retrieved 21 August 2016.
- Judd, W.S.; Campbell, C.S.; Kellogg, E.A.; Stevens, P.F.; Donoghue, M.J. (2007). "Taxonomy". Plant Systematics: A Phylogenetic Approach (3rd ed.). Sunderland: Sinauer Associates.
- Kirk, P.M., Cannon, P.F., Minter, D.W., Stalpers, J.A. eds. (2008) "Taxonomy". In Dictionary of the Fungi, 10th edition. CABI, Netherlands.
- Walker, P.M.B., ed. (1988). The Wordsworth Dictionary of Science and Technology. W.R. Chambers Ltd. and Cambridge University Press.
- "Nomenclature, Names, and Taxonomy". Intermountain Herbarium – USU. 2005. Archived from the original on 23 November 2016.
- Michener, Charles D., John O. Corliss, Richard S. Cowan, Peter H. Raven, Curtis W. Sabrosky, Donald S. Squires, and G. W. Wharton (1970). Systematics In Support of Biological Research. Division of Biology and Agriculture, National Research Council. Washington, D.C. 25 pp.
- Wilkins, J. S. What is systematics and what is taxonomy? Archived 27 August 2016 at the Wayback Machine. Available on http://evolvingthoughts.net
- Brusca, R. C., & Brusca, G. J. (2003). Invertebrates (2nd ed.). Sunderland, Mass. : Sinauer Associates, p. 27
- Mayr, Ernst (1991). Principles of Systematic Zoology. New York: McGraw-Hill, p. 159.
- Mayr, Ernst (1991), p. 162.
- "Taxonomy: Meaning, Levels, Periods and Role". Biology Discussion. 27 May 2016. Archived from the original on 5 April 2017.
- Turrill 1938.
- Turrill 1938, pp. 365–366.
- "Result of Your Query". biological-concepts.com. Archived from the original on 5 April 2017.
- Datta 1988.
- Stace 1989.
- Stuessy 2009.
- Manktelow, M. (2010) History of Taxonomy Archived 29 May 2015 at the Wayback Machine. Lecture from Dept. of Systematic Biology, Uppsala University.
- Mayr, E. (1982) The Growth of Biological Thought. Belknap P. of Harvard U.P., Cambridge (Mass.)
- "Palaeos : Taxonomy". palaeos.com. Archived from the original on 31 March 2017.
- "taxonomy | biology". Encyclopedia Britannica. Archived from the original on 5 April 2017.
- "Biology 101, Ch 20". cbs.dtu.dk. 23 March 1998. Archived from the original on 28 June 2017.
- "Andrea Cesalpino | Italian physician, philosopher, and botanist". Encyclopedia Britannica. Archived from the original on 5 April 2017.
- Cesalpino, Andrea; Marescotti, Giorgio (1583). De plantis libri XVI. Florence: Apud Georgium Marescottum – via Internet Archive.
- "Andrea Cesalpino | Italian physician, philosopher, and botanist". Encyclopedia Britannica. Archived from the original on 5 April 2017.
- John, Ray (1682). Methodus plantarum nova [New Method of Plants] (in Latin). impensis Henrici Faithorne & Joannis Kersey, ad insigne Rofæ Coemeterio D. Pauli. Archived from the original on 29 September 2017.
- "Joseph Pitton de Tournefort | French botanist and physician". Encyclopedia Britannica. Archived from the original on 5 April 2017.
- Linnaeus, C. (1735) Systema naturae, sive regna tria naturae systematice proposita per classes, ordines, genera, & species. Haak, Leiden
- Linnaeus, C. (1753) Species Plantarum. Stockholm, Sweden.
- Linnaeus, C. (1758) Systema naturae, sive regna tria naturae systematice proposita per classes, ordines, genera, & species, 10th Edition. Haak, Leiden
- "taxonomy – The Linnaean system | biology". Encyclopedia Britannica. Archived from the original on 5 April 2017.
- Carl, Clerck; Carl, Bergquist; Eric, Borg; L., Gottman; Lars, Salvius (1757). Svenska spindlar [Swedish Spiders] (in Swedish). Literis Laur. Salvii. Archived from the original on 1 December 2017.
- "taxonomy – Classification since Linnaeus | biology". Encyclopedia Britannica. Archived from the original on 5 April 2017.
- Huxley, T.H. (1876): Lectures on Evolution. New York Tribune. Extra. no. 36. In Collected Essays IV: pp. 46–138 original text w/ figures Archived 28 June 2011 at the Wayback Machine
- "Thomas Henry Huxley | British biologist". Encyclopedia Britannica. Archived from the original on 6 February 2018.
- Taylor, Mike. "What do terms like monophyletic, paraphyletic and polyphyletic mean?". miketaylor.org.uk. Archived from the original on 1 August 2010.
- "Polyphyletic vs. Monophyletic". ncse.com. Archived from the original on 5 April 2017.
- Brower, Andrew V. Z. and Randall T. Schuh. 2021. Biological Systematics: Principles and Applications (3rd edn.) Cornell University Press, Ithaca, New York., p. 13
- Schuh, Randall T. "The Linnaean system and its 250-year persistence." The Botanical Review 69, no. 1 (2003): 59.
- Queiroz, Philip D. Cantino, Kevin de. "The PhyloCode". ohio.edu. Archived from the original on 10 May 2016.
- "PhyloCode: Concept, History and Advantages | Taxonomy". Biology Discussion. 12 July 2016. Archived from the original on 5 April 2017.
- "Kingdom Classification of Living Organism". Biology Discussion. 2 December 2014. Archived from the original on 5 April 2017.
- "Carl Woese | Carl R. Woese Institute for Genomic Biology". www.igb.Illinois.edu. Archived from the original on 28 April 2017.
- Luketa, S. (2012). "New views on the megaclassification of life" (PDF). Protistology. 7 (4): 218–237. Archived (PDF) from the original on 2 April 2015.
- Linnaeus, C. (1735). Systemae Naturae, sive regna tria naturae, systematics proposita per classes, ordines, genera & species.
- Haeckel, E. (1866). Generelle Morphologie der Organismen. Reimer, Berlin.
- Chatton, É. (1925). "Pansporella perplexa. Réflexions sur la biologie et la phylogénie des protozoaires". Annales des Sciences Naturelles - Zoologie et Biologie Animale. 10-VII: 1–84.
- Ruggiero, Michael A. (2014). Families of All Living Organisms, Version 2.0.a.15, (4/26/14). Expert Solutions International, LLC, Reston, VA. 420 pp. Included data available for download via https://www.gbif.org/dataset/8067e0a2-a26d-4831-8a1e-21b9118a299c (doi: 10.15468/tfp6yv)
- "A Few Bad Scientists Are Threatening to Topple Taxonomy". Smithsonian. Retrieved 24 February 2019.
- "What is taxonomy?". London: Natural History Museum. Archived from the original on 1 October 2013. Retrieved 23 December 2017.
- "Mnemonic taxonomy / biology: Kingdom Phylum Class Order..." Archived from the original on 6 June 2017.
- "ICZN Code". animalbase.uni-goettingen.de.
- "International Code of Nomenclature for algae, fungi, and plants". International Association for Plant Taxonomy. Archived from the original on 11 January 2013.
- "How can I describe new species?". International Commission on Zoological Nomenclature. Archived from the original on 6 March 2012. Retrieved 21 May 2020.
- "Taxonomy – Evaluating taxonomic characters". Encyclopædia Britannica. Archived from the original on 22 April 2019.
- "Editing Tip: Scientific Names of Species | AJE | American Journal Experts". www.aje.com. Archived from the original on 9 April 2017.
- "Carolus Linnaeus: Classification, Taxonomy & Contributions to Biology – Video & Lesson Transcript | Study.com". Study.com. Archived from the original on 9 April 2017.
- Biocyclopedia.com. "Biological Classification". biocyclopedia.com. Archived from the original on 14 May 2017.
- "Zoological nomenclature: a basic guide for non-taxonomist authors". Annelida.net. Archived from the original on 16 March 2017.
- "Classification". North Carolina State University. Archived from the original on 14 April 2017. Retrieved 27 April 2017.
- McDonald, David (Fall 2008). "Molecular Marker Glossary". University of Wyoming. Archived from the original on 10 June 2007.
- "About – The Plant List". theplantlist.org.
- "About the Catalogue of Life: 2016 Annual Checklist". Catalogue of Life. Integrated Taxonomic Information System (ITIS). Archived from the original on 15 May 2016. Retrieved 22 May 2016.
- Datta, Subhash Chandra (1988). Systematic Botany (4 ed.). New Delhi: New Age International. ISBN 978-81-224-0013-7. Retrieved 25 January 2015.
- ISBN 978-0-521-42785-2. Retrieved 19 April 2015.
- Stuessy, Tod F. (2009). Plant Taxonomy: The Systematic Evaluation of Comparative Data. Columbia University Press. ISBN 978-0-231-14712-5. Retrieved 6 February 2014.
- Turrill, W.B. (1938). "The Expansion Of Taxonomy With Special Reference To Spermatophyta". Biological Reviews. 13 (4): 342–373. S2CID 84905335.
- Wiley, Edward O. and Bruce S. Lieberman. 2011. "Phylogenetics: Theory and Practice of Phylogenetic Systematics", 2nd edn. ISBN 978-0-470-90596-8
- What is taxonomy? at the Natural History Museum London
- Taxonomy at NCBI the National Center for Biotechnology Information
- Taxonomy at UniProt the Universal Protein Resource
- ITIS the Integrated Taxonomic Information System
- CETaF the Consortium of European Taxonomic Facilities
- Wikispecies free species directory
- Biological classification. Archived 13 August 2020 at the Wayback Machine