Taxonomy

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A taxonomy ( ancient Greek τάξις táxis , order 'and νόμος nómos , law') is a uniform procedure or model (classification scheme) with which objects are classified according to certain criteria, i.e. in categories or classes (also called taxa ). Scientific disciplines use the term taxonomy for a usually hierarchical classification (classes, subclasses, etc.).

Taxonomies are of considerable importance for the development of a science: They make it easier to deal with individual cases and enable summary statements that can lead to an explanation of connections. They force clarity about the differences between the categories and thereby lead to a better understanding of the area of ​​investigation.

Anthropological studies show that the taxonomies used in certain linguistic and cultural areas are embedded in local, cultural and social systems and serve different social purposes. One of the most famous and influential studies of lay taxonomies (folk taxonomies) is Émile Durkheim's The Elementary Forms of Religious Life .

Taxonomy in Biology

Basics

Hierarchy of taxonomic levels (without intermediate levels)

Taxonomy as a branch of biology records living beings (and viruses ) in a system. This division into a hierarchical system is traditionally associated with the classification in a certain rank, such as species , genus or family , especially with organisms , but also with viruses, see virus taxonomy .

In biology, a taxon is a group of living beings (or viruses) that can be described by common characteristics and distinguished from other groups. The list of taxa is the working area of ​​taxonomy, the scientific classification of organisms according to internationally established rules of nomenclature, see biological nomenclature . Taxonomic education is an important part of studying organismic biology.

By delimiting the various taxa, a classification is made according to certain sequence of stages:

German Latin example
domain Dominium Eukaryotes
rich Regnum Animals
Sub-kingdom Multicellular animals
Department / trunk Divisio / Phylum Chordates
Subdivision / sub-stem, sub-phylum Subdivisio / Subphylum Vertebrates
class Classis Mammals
Subclass, subclass Sub-chassis Higher mammals
Infra class ...
Superiority Superordo Laurasiatheria
order Ordo Predators
Subordination ...
Superfamily, superfamily Superfamilia Feline
family Familia Cats
Subfamily Subfamilia Small cats
Tribe Tribe ...
Sub-tribus Subtribe ...
genus genus Old world wildcats
Kind, species Species Wild cat
Subspecies, race, subspecies Subspecies European wild cat

A key position here has the kind . A biological species is a group of natural populations that form a reproductive community and are reproductively isolated from other groups . The isolation mechanisms between the individual species are of a biological nature, i.e. not based on external conditions, but rather created in the living beings themselves. This definition is considered to be the optimal definition of a species because it is not arbitrary, “it could even go so far as to describe it as 'self-operational'” by “emphasizing the criterion of reproductive isolation from other populations”.

Since the biological concept of species cannot be applied to all forms of life (generation times that are too long, sexual reproduction unknown, parthenogenesis ), there are further species definitions such as the morphological species (the most frequently used species definition), the phylogenetic species (due to phylogenetic relationships) or the ecological species in which the morphologically identical or similarly designed species are addressed as different species if they occur geographically separated.

With the publication of Systema Naturae by Carl von Linné , the binary (in zoology also binomial) nomenclature became established. The first part of the name refers herein to the genus (Genus), the second is the epithet ( epithet ) for the type (species).

Methods

Traditional methods were based on morphological characteristics, such as the physique of animals or the structure of flowers in plants . Later, findings from the fields of microscopy , physiology , biochemistry and genetics were incorporated into the taxonomic analysis. Recently, automated, computer-based identification systems are being tested, which are intended to dramatically improve the accuracy and speed of a determination (see below).

The modern biological system is more profound. In her play phylogenetic relationships involved. The different taxa are classified in the system in a hierarchical family tree , which is supposed to reflect their evolutionary ancestry. The rules of cladistics are now considered the standard for classifying organisms, i. H. a taxon should be monophyletic.

Problems

Number of unknown species

A major problem in taxonomy is the sheer number of species to be identified. The number of organisms not yet described taxonomically runs into the millions. While there are far too few taxonomists to the taxonomic evaluation of to be able to accomplish to be detected species in a reasonable time: According to the Global Taxonomy Initiative , there are only about 4,000 to 6,000 professional taxonomists around the world, most of which are in developed countries operate their Biotopes are far less biodiverse than the biotopes of developing countries in the tropics . According to estimates, around 90 percent of all vertebrates are taxonomically recorded today , but less than 50 percent of all terrestrial arthropods (e.g. insects , millipedes , crustaceans and arachnids ) and only about 5 percent of all protozoa living worldwide (single-celled cells with a nucleus) are known ).

Reliability of determination

Another problem is that in many cases even experienced taxonomists are not able to identify species with the required reliability. While larger animals and plants can usually be determined very reliably, the assignment of microscopic organisms is in many cases not possible with 100% accuracy, even for experts. In tests, trained people were able to identify sticklebacks with an accuracy of 84 to 95 percent, but with phytoplankton species, the accuracy dropped to just 72 percent. In studies in which taxonomists were asked to determine predefined species, the experts sometimes only agreed in their decisions for one or the other species in 43 percent of the cases (in another study the agreements ranged between 20 and 70 percent), and also their own Previous selections could only be reproduced in 67 to 83 percent of cases.

This could be remedied by image-based automated identification systems, e.g. B. the Digital Automated Identification System (DAISY) or the Dinoflagellate Categorization by Artificial Neural Network (DiCANN). DAISY was able to identify 15 species of a parasitic wasp with 100% accuracy using digitized images of the wings, each identification taking less than a second. DiCANN achieved a precision of 72 percent in the identification of dinoflagellates - and was therefore just as accurate as experienced experts.

Different nomenclature codes

The taxonomic rules, for example the prescribed endings for the various ranks, whether a species description must be in Latin or may also be in English, are specified in the nomenclature codes. Traditionally, there are only nomenclature codes for bacteria, land plants and animals. The fungi and algae are dealt with in the botanical nomenclature code, the protozoa in the zoological nomenclature code. This separate processing of the organisms leads to collisions and inconsistencies.

For example, the generic name Coccomyxa was used twice: once in the zoological nomenclature code for a pathogen that causes coccomyxomatosis, and once for a green alga . The results of the molecular-phylogenetic investigations showed that the protists are not a monophyletic group, i.e. do not form their own kingdom. In many evolutionary lines of the protists, however, heterotrophic protozoa and photosynthetically active life forms ( algae ) occur. For these groups there are usually competing zoological and botanical classification schemes because they are neither land plants (Embryophyta) nor animals (Metazoa).

Further inconsistencies arise from the research that traditionally focuses strongly on land plants and animals. Since both groups of organisms develop diverse morphological characteristics, they contain much finer and denser classification levels than the genetically more diverse protist lines. According to the results of the phylogenetic analyzes and the rules of cladistics, the animals and fungi must be grouped with the choanoflagellates (Reich Opisthokonta). The same applies to the land plants (Embryophyta), which developed from green algae (Chlorophyta) (together: Unterreich Viridiplantae) and their closest related sister groups are red algae (Rhodoplantae) and Glaucocystophyceae . However, this has the consequence - since the nomenclature codes provide the realm as the highest category - that the land plants (Embryophyta) and the animals (Metazoa) must be downgraded in the rank of the realm to a lower level and also all subsequent lower ranks within the land plants and Animals. Due to the finely branched classification levels within both groups, this is hardly feasible in practice.

The drawer systems of the traditional nomenclature codes need to be revised. Further, higher hierarchical levels might have to be added, the existing ranks would have to be made more flexible and synchronized, which, however, will be difficult due to the bureaucratic structures and the double naming. One consequence of the unsatisfactory situation is an inconsistent use of the system between zoologists, botanists and protozoologists / phycologists.

criticism

In The Order of Things (1966), Michel Foucault problematizes category systems and their space-time dependency ( Archeology of Knowledge , 1969 ). As an example he cites a text by Jorge Luis Borges about different animal categories in "a certain Chinese encyclopedia" in which animals are classified as follows:

Emperor's - embalmed - tamed - milk pigs - sirens - mythical animals - stray dogs - included in this classification - who behave like mad - innumerable - drawn with the finest camel hair brush - and so on - who broke the water jug ​​- those from a distance like flies appearance

This - of course Borges fictitious - example of a classification system shows that category systems can act arbitrarily, when viewed from an outside perspective. Modern taxonomists, like Peter Ax , reject the use of labels like “family” or “order”. The reason for this lies in the fact that these classifications are carried out arbitrarily. There are no natural rules as to why a group of organisms, for example, receives the rank of order instead of that of a class. Therefore only the term “taxon” should be used.

Taxonomic research in Germany

A study on taxonomic research in Germany was published in 2012 as part of the Network Forum on Biodiversity Research Germany project. An overview of the actors and structures in the research field should be given and its social and scientific relevance emphasized. In particular, the position of the taxonomy as a "dying discipline" was reviewed.

Taxonomy in other disciplines

Information processing

Taxonomies are hierarchical classifications of a subject area. They represent superordinate and subordinate relationships and can thus represent inheritance. Ideally, they are based on the analysis of quantitative data. Based on this, a cluster analysis (structural analysis algorithms) is carried out. These taxonomies can then be used generically.

Classifications that have a mono-hierarchical structure are called taxonomy in information processing . Only one superclass is assigned to each class , so that the entire classification shows a tree structure . In this structure, the elements close to the root contain general information. With increasing branching of the taxonomy, the knowledge stored in it becomes more and more specific. This type of classification of knowledge areas within a hierarchy results in simple semantics .

With regard to documents or content, the term taxonomy is used for a classification system , a system or the process of classification. Classifications can be made, for example, by capturing metadata and / or using a filing structure.

→ See also:

Linguistics

In linguistics , taxonomy deals with the segmentation and classification of linguistic terms in order to describe a formal language system.

Learning theory

In learning theory , the learning objectives are classified into different taxonomy levels according to their intellectual demands on the learner. The best known are the learning target levels described by Benjamin Bloom for the cognitive, affective and psychomotor areas.

criticism

In his Philosophical Investigations (1953), Ludwig Wittgenstein pointed to fundamental problems of hierarchical classification systems using the example of family resemblance.

See also

literature

Philosophical discussions on taxonomy and taxonomic terms such as the species term:

Web links

Commons : Taxonomy  - collection of images, videos and audio files
Wiktionary: Taxonomy  - explanations of meanings, word origins, synonyms, translations

Individual evidence

  1. ↑ Taxonomy , in: Wolfgang J. Koschnik: Standard vocabulary for the social sciences , Vol. 2, Munich London New York Paris 1993, ISBN 3-598-11080-4 .
  2. ^ Gerhard de Haan : Study and research on sustainability . Bertelsmann Verlag, Bielefeld 2007, ISBN 978-3-7639-3564-2 , p. 123 ( limited preview in Google Book search).
  3. ↑ Ernst Mayr : Evolution and the variety of life , Springer-Verlag 1979, ISBN 3-540-09068-1 , p. 234f
  4. ↑ a b c MacLeod, N. et al .: Time to automate identification . In: Nature . Vol. 467, No. 7312 , 2010, p. 154-155 , PMID 20829777 (English).
  5. ↑ Their number is even decreasing. See 3sat, nano, June 10, 2013
  6. ↑ Global Taxonomy Initiative: The Taxonomic Impediment. Convention on Biological Diversity , accessed October 8, 2010 .
  7. ^ A b Norman MacLeod (Ed.): Automated Taxon Identification in Systematics: Theory, Approaches and Applications. CRC Press, New York 2008, ISBN 978-0-8493-8205-5
  8. ↑ Jorge Luis Borges Borges: The analytical language of John Wilkins . Inquisitions. Essays 1941–1952. Trans. V. Karl August Horst u. Gisbert Haefs
  9. ↑ Reiner Ruffing: Michel Foucault . Chapter 3: The Order of Things , p. 41; Wilhelm Fink Verlag GmbH & Co., Paderborn, 2008. ISBN 978-3-7705-4608-4
  10. ↑ Taxonomic research in Germany - an overview study ( Memento from November 9, 2014 in the Internet Archive ) (PDF; 4.6 MB) by the Network Forum for Biodiversity Research Germany (NeFo). As of May 29, 2012
  11. ↑ http://www.biodiversity.de/
  12. ↑ Who counts the species, names the names? - Press release from the Natural History Museum Berlin on the new taxonomic study. As of May 21, 2012
  13. ^ Krcmar, Helmut: Information Management . 6., revised. Springer, Berlin 2015, ISBN 978-3-662-45862-4 , pp. 135 .
  14. ^ David Alan Cruse: Lexical Semantics. Cambridge Univ. Press, Cambridge 2001, ISBN 0-521-27643-8