In biology and palaeobiology, the first description is the first scientific description of a living being that has not been known to science and that meets certain formal requirements . In particular, the first description is the decisive basis for assigning a scientific name to a species . Due to the great importance of the species as a fundamental unit of biological science, strict, formalized rules apply.
The first description is an act of taxonomy and as such is independent of the species concept used. A species as a taxon is any taxonomic unit named according to the rules. The biological nomenclature is intended to ensure that every organism can be given a scientific name and that there is only one unambiguous valid name for every organism.
In order to be able to describe a group of individuals as a species, it is first necessary to distinguish them from other individuals that have already been described. This delimitation must necessarily precede the description and represents an independent problem. For this delimitation characteristics are collected and the individuals are compared with one another on this basis. If one finds a definable group of individuals whose combination of features differs in a systematic way from that of another group, then one has candidates for two different species. In principle, this can also be done with a single specimen, but this is risky because the individuals often show a noticeable variability within a species; it is not prohibited, but should be avoided whenever possible. In the next step it must be ensured that the groups delimited in this way have not already been described first, i.e. H. have already been given a valid name. If such a group is mistakenly given a name a second time later, this is validly published if it complies with the rules, but will not be used by science if the identity is noticed. This is called a synonym . If a group (this should correspond to a population . However, this cannot be determined directly) has been delimited on the basis of unambiguous characteristics that does not yet have a valid name, then one has a candidate for a new species. The initial description is then made for these.
The first description is therefore independent of the discovery and of the delimitation and identification of the species. It always occurs later than this, in some cases decades later. It is not enough to have recognized the new unit, it is always necessary to classify it in the systematics of biology. For this purpose, their characteristics must be compared with all possibly relevant publications that have already been written about related or comparable groups. In many cases this is not enough either, because older descriptions in particular can be incomplete. Then individuals stored in museums and collections have to be compared directly, in the case of DNA also reference sequences stored in databases.
Content of the description
A species is described in a scientific publication . What is recognized as a "publication" and what is not is regulated in the codes used. The species can be described in a separate work, but this often happens when an entire group of organisms is carefully revised (called a revision or monograph) or in the context of a catalog that also lists all the species that have already been described and known. In order for the species to be described, the descriptive work must therefore be accepted by the magazine or publisher in which it is to appear; It must therefore correspond to the usual formalities of a scientific publication (usually with a summary, introduction, methodology, results, discussion, references). It must be clear from the work that it is intended to describe a new species. For this purpose, the new species name proposed by the first describer and corresponding to the rules of the corresponding code, followed by "nova species" (or "new species", very often abbreviated to "n.sp."), must be stated in the paper. Next, a diagnosis of the characteristics of the new species is required. For this purpose, the relevant characteristics are described, often in key words, so that the new species can be recognized and differentiated from other related species. Drawings or photos of the features are also common today. The introduction of a species name without diagnosis is not permitted. However, it is not stipulated in any of the codes what a diagnosis must contain, this is not formalized (such a formalization has already been proposed, but this has not been accepted). In the case of cryptospecies , it may consist of just a DNA sequence (although some taxonomists would not recognize such a species). As a rule, however, it will be a morphological differential diagnosis in which the characteristics of the new species are compared with those already described in order to work out their differences. In botany it was a requirement until 2011 that the diagnosis (at least also) was made in Latin (Article 38), since then English has also been permitted.
The description can, but does not have to, contain further information, for example on the ecology and distribution of the new species. These only have to be included if corresponding properties (e.g. behavior) are to serve as characteristics themselves.
In the description, an individual must be specified, which is archived as a type (in the case of bacterial species: a bacterial culture ) (an illustration is only sufficient in rare exceptional cases ). As a reference for comparisons, it should allow a reliable determination of specimens found later. The species name of the newly described species is linked to the type, not to the description. This is to ensure nomenclature stability. In many cases it is the case that new diagnostic features are discovered in groups of organisms, according to which species can be separated. Because they are new, they cannot be included in the original diagnosis. If what was previously considered to be one species is now split into two new ones, it is not easily possible to decide which of them formed the basis of the original description. In this case the new editors will consult the type on which they are checking the characteristics. Those organisms that agree with the type keep the previous name.
The rules to be followed for naming and describing species are laid down in the nomenclature codes. For historical reasons there is not one code for all organisms, but separate sets of rules,
- for animals (zoology) the International Code of Zoological Nomenclature ICZN ,
- for plants (botany), the International Code of Nomenclature for Algae, Fungi and Plants (ICN) ,
- for the prokaryotes the International Code of Nomenclature of Bacteria ,
which each differ in details.
The codes are particularly important for the form of the name, while the differences are smaller for the initial description itself.
The first description had to take place in a printed work until 2011, since then an electronic copy with fixed content and layout, e.g. B. a PDF document, permitted (Article 8). A physical object, either paper or a duplicated optical data storage medium, must be available; in the case of publication on the Internet (only allowed since 2011), the publication must have been registered in the Official Register of Zoological Nomenclature (ZooBank). Still not allowed are z. B. photocopies, lecture scripts, collection labels, microfilms, audio files, but also prior publications. Not the publication itself, but at least the name must be written in Latin letters (Article 11). The new name must (since 1999) be explicitly marked as new (Article 16).
In botany, too, since 2012, in addition to printed works, electronically published works, e.g. B. pdf files, allowed for the initial description (Article 29). An ISBN or ISSN is required for electronic publications . Also here are z. B. Lectures, other electronic media and prior publications / rough versions excluded. Corrections are only allowed if they are published independently and do not change anything in the content of the initial description itself. Non-scientific works, such as popular magazines and catalogs, are excluded, but also doctoral theses (not published separately).
If a species description is not possible, as is the case with such fossils , where the species diagnosis is often unsuccessful due to incomplete conservation , a more inaccurate classification is made in the first description and so-called parataxa are established. In paleobotany such partial names , which are established on the basis of parts of an organism, are referred to as a form or organ genus or species. Partial names are also used in paleozoology . A well-known example of this are the tooth-like fossils of the conodonts , which due to their widespread distribution and their wealth of shapes represent a very important key fossil in the Paleozoic (ancient times), although the associated "conodont animal" was not known for a long time and was only discovered in 1981.
First description based on DNA sequences
Since it has become possible to amplify and sequence DNA relatively easily and cheaply on a large scale, these sequences are increasingly used as taxonomic tools. In many cases, DNA barcoding techniques make it possible to quickly and reliably identify species described on a different basis. However, there are increasing efforts to use sequences themselves as characteristics for the description of the species, possibly even as the only characteristic. This approach is controversial in science to this day, but is gaining increasing influence. Proponents argue that it is ultimately just a new type of trait that does not differ in principle from morphological traits and may allow new insights into evolution and biology. Opponents point out possible dangers and opportunities for abuse. However, it was repeatedly pointed out that data obtained in this way are not superior per se and that a careful weighing of all characteristics remains necessary.
The first person to describe a species is the author of the scientific publication in which the species was described. If the work was written by several people, they are all first descriptors. There are only exceptions if someone else is expressly named as the first person to describe the work or if this is clearly recognizable.
- Judith E. Winston: Describing Species. Practical Taxonomic Procedure for Biologists. Columbia University Press, New York 1999, ISBN 0-231-06824-7 .
- Ernst Mayr : What is a Species, and What is Not? In: Philosophy of Science. Volume 63, 1996, pp. 262-277 ( full text online).
- L. G. Cook, RD Edwards, MD Crisp, NB Hardy: Need morphology always be required for new species descriptions? In: Invertebrate Systematics. Volume 24, 2010, pp. 322-332, DOI: 10.1071 / IS1001 .
- Barry Bolton: How to conduct large-scale taxonomic revisions in Formicidae? In: RR Snelling, BL Fisher, PS Ward (Eds.): Advances In Ant Systematics (Hymenoptera: Formicidae): Homage To EO Wilson - 50 Years Of Contributions. In: Memoirs of the American Entomological Institute. Volume 80, 2007, pp. 52-71 (using the example of the ants (Formicidae)).
- Andrew R. Deans, Matthew J. Yoder, James P. Balhoff: Time to change how we describe biodiversity. In: Trends in Ecology and Evolution. Volume 27, No. 2, 2012, pp. 78-84, doi : 10.1016 / j.tree.2011.11.007 .
- Craig A. Burnside, Paul T. Smith, Srinivas Kambhampati: Three New Species of the Wood Roach, Cryptocercus (Blattodea: Cryptocercidae), from the Eastern United States. In: Journal of the Kansas Entomological Society. Vol. 72, No. 4, 1999, pp. 361-378, JSTOR 25085925 (an example).
- Katharina M. Jörger, Michael Schrödl: How to describe a cryptic species? Practical challenges of molecular taxonomy. In: Frontiers in Zoology. Volume 10, No. 59, 2013, pp. 1–27, DOI: 10.1186 / 1742-9994-10-59 .
- Joan Pons, Timothy G. Barraclough, Jesus Gomez-Zurita, Anabela Cardoso, Daniel P. Duran, Steaphan Hazell, Sophien Kamoun, William D. Sumlin, Alfried P. Vogler: Sequence-Based Species Delimitation for the DNA Taxonomy of Undescribed Insects . In: Systematic Biology. Volume 55, No. 4, 2006, pp. 595-609, doi : 10.1080 / 10635150600852011 .
- Leandro M. Santos, Luiz RR Faria: The taxonomy's new clothes: a little more about the DNA-based taxonomy. In: Zootaxa. Volume 3025, 2011, pp. 66-68 ( PDF file ).
- Timothy J. Pages, Jane M. Hughes: Neither molecular nor morphological data have all the answers; with an example from Macrobrachium (Decapoda: Palaemonidae) from Australia. In: Zootaxa. Volume 2874, 2011, pp. 65-68 ( PDF file ).