Linnaean taxonomy

Last updated
The title page of Systema Naturae, Leiden (1735) Linne-Systema Naturae 1735.jpg
The title page of Systema Naturae, Leiden (1735)

Linnaean taxonomy can mean either of two related concepts:

Contents

  1. the particular form of biological classification (taxonomy) set up by Carl Linnaeus, as set forth in his Systema Naturae (1735) and subsequent works. In the taxonomy of Linnaeus there are three kingdoms, divided into classes, and they, in turn, into orders, genera (singular: genus), and species (singular: species) [1] , with an additional rank lower than species.
  2. a term for rank-based classification of organisms, in general. That is, taxonomy in the traditional sense of the word: rank-based scientific classification. This term is especially used as opposed to cladistic systematics, which groups organisms into clades. It is attributed to Linnaeus, although he neither invented the concept of ranked classification (it goes back to Plato and Aristotle) nor gave it its present form. In fact, it does not have an exact present form, as "Linnaean taxonomy" as such does not really exist: it is a collective (abstracting) term for what actually are several separate fields, which use similar approaches.

Linnaean name also has two meanings: depending on the context, it may either refer to a formal name given by Linnaeus (personally), such as Giraffa camelopardalis Linnaeus, 1758, or a formal name in the accepted nomenclature (as opposed to a modernistic clade name).

The taxonomy of Linnaeus

In his Imperium Naturae, Linnaeus established three kingdoms, namely Regnum Animale, Regnum Vegetabile and Regnum Lapideum. This approach, the Animal, Vegetable and Mineral Kingdoms, survives today in the popular mind, notably in the form of the parlour game question: "Is it animal, vegetable or mineral?". The work of Linnaeus had a huge impact on science; it was indispensable as a foundation for biological nomenclature, now regulated by the nomenclature codes. Two of his works, the first edition of the Species Plantarum (1753) for plants and the tenth edition of the Systema Naturae (1758), are accepted as part of the starting points of nomenclature; his binomials (names for species) [2] and generic names take priority over those of others. However, the impact he had on science was not because of the value of his taxonomy.

Classification for plants

His classes and orders of plants, according to his Systema Sexuale, were never intended to represent natural groups (as opposed to his ordines naturales in his Philosophia Botanica ) but only for use in identification. They were used for that purpose well into the nineteenth century. [3] Within each class were several orders.

Key to the Sexual System (from the 10th, 1758, edition of the Systema Naturae) SN-p837.jpg
Key to the Sexual System (from the 10th, 1758, edition of the Systema Naturae)
Kalmia is classified according to Linnaeus' sexual system in class Decandria, order Monogyna, because it has 10 stamens and one pistil Kalmia latifolia Great Smoky.jpg
Kalmia is classified according to Linnaeus' sexual system in class Decandria, order Monogyna, because it has 10 stamens and one pistil

The Linnaean classes for plants, in the Sexual System, were:

The classes based on the number of stamens were then subdivided by the number of pistils, e.g. Hexandria monogynia with six stamens and one pistil. [6] Index to genera p. 1201 [7]

By contrast his ordines naturales numbered 69, from Piperitae to Vagae.

Classification for animals

The 1735 classification of animals Linnaeus - Regnum Animale (1735).png
The 1735 classification of animals

Only in the Animal Kingdom is the higher taxonomy of Linnaeus still more or less recognizable and some of these names are still in use, but usually not quite for the same groups. He divided the Animal Kingdom into six classes, in the tenth edition, of 1758, these were:

Classification for minerals

His taxonomy of minerals has long since dropped from use. In the tenth edition, 1758, of the Systema Naturae, the Linnaean classes were:

Rank-based scientific classification

This rank-based method of classifying living organisms was originally popularized by (and much later named for) Linnaeus, although it has changed considerably since his time. The greatest innovation of Linnaeus, and still the most important aspect of this system, is the general use of binomial nomenclature, the combination of a genus name and a second term, which together uniquely identify each species of organism within a kingdom. For example, the human species is uniquely identified within the animal kingdom by the name Homo sapiens. No other species of animal can have this same binomen (the technical term for a binomial in the case of animals). Prior to Linnaean taxonomy, animals were classified according to their mode of movement.

Linnaeus's use of binomial nomenclature was anticipated by the theory of definition used in Scholasticism. Scholastic logicians and philosophers of nature defined the species man, for example, as Animal rationalis, where animal was considered a genus and rationalis (Latin for "rational") the characteristic distinguishing man from all other animals. Treating animal as the immediate genus of the species man, horse, etc. is of little practical use to the biological taxonomist, however. Accordingly, Linnaeus's classification treats animal as a class including many genera (subordinated to the animal "kingdom" via intermediary classes such as "orders"), and treats homo as the genus of a species Homo sapiens, with sapiens (Latin for "knowing" or "understanding") playing a differentiating role analogous to that played, in the Scholastic system, by rationalis (the word homo, Latin for "human being", was used by the Scholastics to denote a species, not a genus).

A strength of Linnaean taxonomy is that it can be used to organize the different kinds of living organisms, simply and practically. Every species can be given a unique (and, one hopes, stable) name, as compared with common names that are often neither unique nor consistent from place to place and language to language. This uniqueness and stability are, of course, a result of the acceptance by working systematists (biologists specializing in taxonomy), not merely of the binomial names themselves, but of the rules governing the use of these names, which are laid down in formal nomenclature codes.

Species can be placed in a ranked hierarchy, starting with either domains or kingdoms. Domains are divided into kingdoms. Kingdoms are divided into phyla (singular: phylum) for animals; the term division, used for plants and fungi, is equivalent to the rank of phylum (and the current International Code of Botanical Nomenclature allows the use of either term). Phyla (or divisions) are divided into classes , and they, in turn, into orders , families , genera (singular: genus), and species (singular: species). There are ranks below species: in zoology, subspecies (but see form or morph ); in botany, variety (varietas) and form (forma), etc.

Groups of organisms at any of these ranks are called taxa (singular: taxon ) or taxonomic groups.

The Linnaean system has proven robust and it remains the only extant working classification system at present that enjoys universal scientific acceptance. However, although the number of ranks is unlimited, in practice any classification becomes more cumbersome the more ranks are added. Among the later subdivisions that have arisen are such entities as phyla, families, and tribes, as well as any number of ranks with prefixes (superfamilies, subfamilies, etc.). The use of newer taxonomic tools such as cladistics and phylogenetic nomenclature has led to a different way of looking at evolution (expressed in many nested clades) and this sometimes leads to a desire for more ranks. An example of such complexity is the scheme for mammals proposed by McKenna and Bell.

Alternatives

Over time, the understanding of the relationships between living things has changed. Linnaeus could only base his scheme on the structural similarities of the different organisms. The greatest change was the widespread acceptance of evolution as the mechanism of biological diversity and species formation, following the 1859 publication of Charles Darwin's On the Origin of Species . It then became generally understood that classifications ought to reflect the phylogeny of organisms, their descent by evolution. This led to evolutionary taxonomy, where the various extant and extinct are linked together to construct a phylogeny. This is largely what is meant by the term 'Linnaean taxonomy' when used in a modern context. In cladistics, originating in the work of Willi Hennig, 1950 onwards, each taxon is grouped so as to include the common ancestor of the group's members (and thus to avoid phylogeny). Such taxa may be either monophyletic (including all descendants) such as genus Homo , or paraphyletic (excluding some descendants), such as genus Australopithecus .

Originally, Linnaeus established three kingdoms in his scheme, namely for Plants, Animals and an additional group for minerals, which has long since been abandoned. Since then, various life forms have been moved into three new kingdoms: Monera, for prokaryotes (i.e., bacteria); Protista, for protozoans and most algae; and Fungi. This five kingdom scheme is still far from the phylogenetic ideal and has largely been supplanted in modern taxonomic work by a division into three domains: Bacteria and Archaea, which contain the prokaryotes, and Eukaryota, comprising the remaining forms. These arrangements should not be seen as definitive. They are based on the genomes of the organisms; as knowledge on this increases, classifications will change. [8]

Representing presumptive evolutionary relationships, especially given the wide acceptance of cladistic methodology and numerous molecular phylogenies that have challenged long-accepted classifications, within the framework of Linnaean taxonomy, is sometimes seen as problematic. Therefore, some systematists have proposed a PhyloCode to replace it.

See also

Related Research Articles

Carl Linnaeus Swedish botanist, physician, and zoologist

Carl Linnaeus, also known after his ennoblement as Carl von Linné, was a Swedish botanist, zoologist, and physician who formalised binomial nomenclature, the modern system of naming organisms. He is known as the "father of modern taxonomy". Many of his writings were in Latin, and his name is rendered in Latin as Carolus Linnæus.

Clade A group of organisms that consists of a common ancestor and all its lineal descendants

A clade, also known as monophyletic group, is a group of organisms that consists of a common ancestor and all its lineal descendants, and represents a single "branch" on the "tree of life". Rather than the English term, the equivalent Latin term cladus is often used in taxonomical literature.

Taxonomy (biology) The science of identifying, describing, defining and naming groups of biological organisms

In biology, taxonomy is the science of naming, defining (circumscribing) and classifying groups of biological organisms on the basis of shared characteristics. Organisms are grouped together into taxa and these groups are given a taxonomic rank; groups of a given rank can be aggregated to form a super-group of higher rank, thus creating a taxonomic hierarchy. The principal ranks in modern use are domain, kingdom, phylum, class, order, family, genus, and species. The Swedish botanist Carl Linnaeus is regarded as the founder of the current system of taxonomy, as he developed a system known as Linnaean taxonomy for categorizing organisms and binomial nomenclature for naming organisms.

Zoology is the branch of biology that studies the animal kingdom, including the structure, embryology, evolution, classification, habits, and distribution of all animals, both living and extinct, and how they interact with their ecosystems. The term is derived from Ancient Greek ζῷον, zōion, i.e. "animal" and λόγος, logos, i.e. "knowledge, study".

A genus is a taxonomic rank used in the biological classification of living and fossil organisms, as well as viruses, in biology. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclature, the genus name forms the first part of the binomial species name for each species within the genus.

Binomial nomenclature System of identifying species of organisms using a two-part name

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, a binomen, binominal name or a scientific name; more informally it is also called a Latin name.

In biological classification, class is a taxonomic rank, as well as a taxonomic unit, a taxon, in that rank. Other well-known ranks in descending order of size are life, domain, kingdom, phylum, order, family, genus, and species, with class fitting between phylum and order.

In biological classification, the order is

  1. a taxonomic rank used in the classification of organisms and recognized by the nomenclature codes. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family. An immediately higher rank, superorder, may be added directly above order, while suborder would be a lower rank.
  2. a taxonomic unit, a taxon, in that rank. In that case the plural is orders.
Taxon Group of one or more populations of an organism or organisms which have distinguishing characteristics in common

In biology, a taxon is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular name and given a particular ranking, especially if and when it is accepted or becomes established. It is not uncommon, however, for taxonomists to remain at odds over what belongs to a taxon and the criteria used for inclusion. If a taxon is given a formal scientific name, its use is then governed by one of the nomenclature codes specifying which scientific name is correct for a particular grouping.

In biology, a common name of a taxon or organism; also known as a vernacular name, English name, colloquial name, trivial name, trivial epithet, country name, popular name, or farmer's name; is a name that is based on the normal language of everyday life; this kind of name is often contrasted with the scientific name for the same organism, which is Latinized. A common name is sometimes frequently used, but that is by no means always the case.

<i>Systema Naturae</i> major work by Carolus Linnaeus

Systema Naturae is one of the major works of the Swedish botanist, zoologist and physician Carl Linnaeus (1707–1778) and introduced the Linnaean taxonomy. Although the system, now known as binomial nomenclature, was partially developed by the Bauhin brothers, Gaspard and Johann, 200 years earlier, Linnaeus was first to use it consistently throughout his book. The first edition was published in 1735. The full title of the 10th edition (1758), which was the most important one, was Systema naturæ per regna tria naturæ, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis or translated: "System of nature through the three kingdoms of nature, according to classes, orders, genera and species, with characters, differences, synonyms, places".

<i>Species Plantarum</i> book by Carl Linnæus

Species Plantarum is a book by Carl Linnaeus, originally published in 1753, which lists every species of plant known at the time, classified into genera. It is the first work to consistently apply binomial names and was the starting point for the naming of plants.

Nomenclature codes or codes of nomenclature are the various rulebooks that govern biological taxonomic nomenclature, each in their own broad field of organisms. To an end-user who only deals with names of species, with some awareness that species are assignable to families, it may not be noticeable that there is more than one code, but beyond this basic level these are rather different in the way they work.

Ichnotaxon term in zoological nomenclature

An ichnotaxon is "a taxon based on the fossilized work of an organism", i.e. the non-human equivalent of an artifact. Ichnotaxa comes from the Greek ίχνος, ichnos meaning track and ταξις, taxis meaning ordering.

<i>Philosophia Botanica</i> book by Carolus Linnaeus

Philosophia Botanica was published by the Swedish naturalist and physician Carl Linnaeus (1707–1778) who greatly influenced the development of botanical taxonomy and systematics in the 18th and 19th centuries. It is "the first textbook of descriptive systematic botany and botanical Latin". It also contains Linnaeus's first published description of his binomial nomenclature.

Taxonomic rank Level in a taxonomic hierarchy

In biological classification, taxonomic rank is the relative level of a group of organisms in a taxonomic hierarchy. Examples of taxonomic ranks are species, genus, family, order, class, phylum, kingdom, domain, etc.

<i>Genera Plantarum</i> book by Linnaeus

Genera Plantarum is a publication of Swedish naturalist Carl Linnaeus (1707–1778). The first edition was issued in Leiden, 1737. The fifth edition served as a complementary volume to Species Plantarum (1753). Article 13 of the International Code of Nomenclature for algae, fungi, and plants states that "Generic names that appear in Linnaeus' Species Plantarum ed. 1 (1753) and ed. 2 (1762–63) are associated with the first subsequent description given under those names in Linnaeus' Genera Plantarum ed. 5 (1754) and ed. 6 (1764)." This defines the starting point for nomenclature of most groups of plants.

<i>Critica Botanica</i> book

Critica Botanica was written by Swedish botanist, physician, zoologist and naturalist Carl Linnaeus (1707–1778). The book was published in Germany when Linnaeus was twenty-nine with a discursus by the botanist Johannes Browallius (1707–1755), bishop of Åbo. The first and only edition was published in July 1737 under the full title Critica botanica in qua nomina plantarum generica, specifica & variantia examini subjiciuntur, selectoria confirmantur, indigna rejiciuntur; simulque doctrina circa denominationem plantarum traditur. Seu Fundamentorum botanicorum pars IV Accedit Johannis Browallii De necessitate historiae naturalis discursus.

12th edition of <i>Systema Naturae</i> scientific work

The 12th edition of Systema Naturae was the last edition of Systema Naturae to be overseen by its author, Carl Linnaeus. It was published in three volumes, with parts appearing from 1766 to 1768. It contains many species not covered in the previous edition, the 10th edition which was the starting point for zoological nomenclature.

References

  1. Frängsmyr, Tore; Lindroth, Sten (1994). Linnaeus, the man and his work (Revised ed.). Canton, MA, USA: Science History Publications/USA. ISBN   978-0881351552. OCLC   30154266.
  2. Systema naturae 250 : the Linnaean ark. Polaszek, Andrew. Boca Raton, FL: CRC Press. 2010. ISBN   9781420095012. OCLC   237886102.CS1 maint: others (link)
  3. Comstock, J.L. (1837). An introduction to the study of botany: including a treatise on vegetable physiology, and descriptions of the most common plants in the middle and northern states. Robinson, Pratt & Co.
  4. Linnaeus 1753, Hexandria monogynia pp. 285–352.
  5. Linnaeus 1753, Hexandria polyynia pp. 342–343.
  6. "Linnaeus Sexual System". CronkLab. Biodiversity Research Centre, University of British Columbia. Retrieved 26 January 2015.
  7. Linnaeus 1753, Index generum p. 1201.
  8. Embley, T. A. & Martin, W. (2006). "Eukaryotic evolution, changes and challenges". Nature. 440. pp. 623–630. doi:10.1038/nature04546.

Bibliography

Note: This is a selected list of the more influential systems. There are many other systems, for instance a review of earlier systems, published by Lindley in his 1853 edition, and Dahlgren (1982). Examples include the works of Scopoli, Batsch and Grisebach.