Linnaean taxonomy can mean either of two related concepts:
Linnaean name also has two meanings, depending on the context: it may either refer to a formal name given by Linnaeus (personally), such asGiraffa camelopardalis Linnaeus, 1758; or a formal name in the accepted nomenclature (as opposed to a modernisticclade name).
In hisImperium Naturae,Linnaeus established three kingdoms, namelyRegnum Animale,Regnum Vegetabile andRegnum 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 itanimal, vegetable or mineral?", and inGilbert and Sullivan's "Major-General's Song". The work of Linnaeus had a huge impact on science; it was indispensable as a foundation forbiological nomenclature, now regulated by thenomenclature codes. Two of his works, the first edition of theSpecies Plantarum (1753) for plants and the tenth edition of theSystema Naturae (1758), are accepted as part of the starting points of nomenclature; his binomials (names for species) and generic names takepriority over those of others.[1] However, the impact he had on science was not because of the value of his taxonomy.
Linnaeus' kingdoms were in turn divided intoclasses, and they, in turn, intoorders,genera (singular:genus), andspecies (singular:species), with an additional rank lower than species, though these do not precisely correspond to the use of these terms in modern taxonomy.[2]
InSystema Naturae (1735), his classes and orders of plants, according to hisSystema Sexuale, were not intended to represent natural groups (as opposed to hisordines naturales in hisPhilosophia Botanica) but only for use in identification. However, in 1737 he publishedGenera Plantarum in which he claimed that his classification of genera was a natural system.[3] His botanical classification and sexual system were used well in the nineteenth century.[4] Within each class were several orders. This system is based on the number and arrangement of male (stamens) and female (pistils) organs.[5]
The Linnaean classes for plants, in the Sexual System, were (page numbers refer toSpecies plantarum):
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.[29] Index to genera p. 1201[30]
By contrast hisordines naturales numbered 69, from Piperitae to Vagae.
.png)
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:
His taxonomy ofminerals has long since been dropped from use. In the tenth edition, 1758, of theSystema Naturae, the Linnaean classes were:
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 ofbinomial nomenclature, the combination of agenus name and a second term, which together uniquely identify eachspecies of organism within a kingdom. For example, thehuman species is uniquely identified within the animal kingdom by the nameHomo sapiens. No other species of animal can have this samebinomen (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 inScholasticism. Scholastic logicians and philosophers of nature defined the species human, for example, asAnimal rationalis, whereanimal was considered a genus andrationalis (Latin for "rational") the characteristic distinguishing humans from all other animals. Treatinganimal as the immediate genus of the species human, horse, etc. is of little practical use to the biological taxonomist, however. Accordingly, Linnaeus's classification treatsanimal as a class including many genera (subordinated to the animal "kingdom" via intermediary classes such as "orders"), and treatshomo as the genus of a speciesHomo sapiens, withsapiens (Latin for "knowing" or "understanding") playing a differentiating role analogous to that played, in the Scholastic system, byrationalis (the wordhomo, 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 livingorganisms, 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 workingsystematists (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 formalnomenclature codes.
Species can be placed in arankedhierarchy, starting with eitherdomains orkingdoms. Domains are divided intokingdoms. Kingdoms are divided intophyla (singular:phylum) — foranimals; the termdivision, used forplants andfungi, is equivalent to the rank of phylum (and the currentInternational Code of Botanical Nomenclature allows the use of either term). Phyla (or divisions) are divided intoclasses, and they, in turn, intoorders,families,genera (singular:genus), andspecies (singular:species). There are ranks below species: in zoology,subspecies (but seeform ormorph); in botany,variety (varietas) andform (forma), etc.
Groups of organisms at any of these ranks are calledtaxa (singular:taxon) ortaxonomic 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 ascladistics andphylogenetic nomenclature has led to a different way of looking at evolution (expressed in many nestedclades) and this sometimes leads to a desire for more ranks. An example of such complexity is thescheme for mammals proposed by McKenna and Bell.
Over time, 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 ofevolution as the mechanism of biological diversity and species formation, following the 1859 publication of Charles Darwin'sOn the Origin of Species. It then became generally understood that classifications ought to reflect thephylogeny of organisms, their descent by evolution. This led toevolutionary taxonomy, where the variousextant andextinct are linked together to construct a phylogeny. This is largely what is meant by the term 'Linnaean taxonomy' when used in a modern context.Incladistics, originating in the work ofWilli Hennig, 1950 onwards, each taxon is grouped so as to include the common ancestor of the group's members (and thus to avoidphylogeny). Such taxa may be eithermonophyletic (including all descendants) such as genusHomo, orparaphyletic (excluding some descendants), such as genusAustralopithecus.
Originally, Linnaeus established three kingdoms in his scheme, namely forPlants,Animals and an additional group forminerals, which has long since been abandoned. Since then, various life forms have been moved into three new kingdoms:Monera, forprokaryotes (i.e., bacteria);Protista, for protozoans and most algae; andFungi. This five-kingdom scheme is still far from thephylogenetic ideal and has largely been supplanted in modern taxonomic work by a division into three domains:Bacteria andArchaea, which contain the prokaryotes, andEukaryota, comprising the remaining forms. These arrangements should not be seen as definitive. They are based on thegenomes of the organisms; as knowledge on this increases, classifications will change.[31]
Representing presumptive evolutionary relationships within the framework of Linnaean taxonomy is sometimes seen as problematic, especially given the wide acceptance ofcladistic methodology and numerousmolecular phylogenies that have challenged long-accepted classifications. Therefore, some systematists have proposed aPhyloCode to replace it.
|  | ||||||||||||||||||||||||||||||||||||||||||||||||||
| |||||||||||||||||||||||||||||||||||||||||||||||||||
| |||||||||||||||||||||||||||||||||||||||||||||||||||
| |||||||||||||||||||||||||||||||||||||||||||||||||||
| Published works |
|  |
|---|---|---|
| General | ||
| Apostles of Linnaeus | ||
| Related people | ||
| Recognitions |
| |
