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Taxonomy in a nutshell

Taxonomy in a nutshell

By Dirk Van den Abeele
Ornitho-Genetics VZW
MUTAVI, Research & Advice Group

Published BVA-International magazin August 2017

I can imagine that most aviculturists are occasionally lost and wonder what taxonomy is, and more to the point what the connection with our hobby actually is? An understandable reaction. I can imagine that most of us have been breeding birds for decades and have never asked this question or have concerned ourselves with taxonomy, but still, taxonomy is closely related to our hobby.

Taxonomy is that part of science which deals with the classification of organisms into various groups. Taxonomy is derived from the Greek táxis meaning ordering, arrangement and nómos meaning usage, law. People involved in taxonomy are called taxonomists. They study the various life forms and place the species within a certain genus (plural genera). So these are the people who placed our Lovebirds within the genus Agapornis and who decided which species belong to this genus.

I must admit that taxonomy does not really influence the way we breed our birds and may seem less interesting, but it is still important if we want to get a broader view of our hobby, that we gain more knowledge about this subject matter. Unfortunately we often saw in the past that hobbyists made mistakes and as a result ridiculed our hobby. For instance in the past there were judges who assumed that Agapornis nigrigenis should be changed to Agapornis nigrigenus or who sometimes even assumed new names had to be decided on for certain species. Trust me, we definitely do not need any of this mess.

Taxonomy is definitely not a new science because over the centuries a lot of scientists have described plants and animals and have tried, each in their own way and according to their beliefs, to divide the species into certain classes and groups. It is therefore normal that this knowledge, just like other sciences, has evolved a lot over the years and that taxonomy classifications have been adjusted in the meantime. On a regular basis recent studies provide a different insight into the relationships between certain species, this can result in a different classification of these species. It goes without saying that this might lead to confusion.

Because most aviculturists do not immediately have access to these publications I can provide one solid piece of advice: use the most recent classifications as the basis for your work. This will avoid a lot of misunderstandings.

The first written records known about taxonomy are from Aristotle. This Greek philosopher lived from 384 until 322 before Christ in Stagira. He tried, probably as one of the first, to create a systematic division of the animal kingdom. This division was of course based on the species known back then, so it goes without saying that this list has been augmented and if necessary adjusted over the centuries.

This however was not as obvious then as it might seem. Each new species discovered had to be added to the existing lists and since the exchange of data was not as easy back then as it is today and, due to a lack of clear guidelines in this matter, each taxonomist had his own way of working. Therefore it occurred that certain species were described multiple times and under different names. Name confusion, which still bothers us even today.

Throughout history, different divisions have been created and a large number of naming systems have been proposed. Numerous organisations and people have each attempted to create a consistent naming system which is solid enough to avoid naming confusions. Usually these attempts went unnoticed because they were not sufficiently supported and hence missed the necessary foundation.

The first really serious attempt to create rules and agreements concerning the naming of species was done by Mr Strickland. Hugh Strickland (1811 – 1853) was an English scientist who, together with The British Association for the advancement of Science, put – new and already existing – rules and agreements regarding taxonomy down on paper [1], [2]. Thanks to this work everything became clearer. Luckily these proposals did not go unnoticed and because Strickland took on the majority of the work, these rules were named after him: Strickland’s rules or Strickland’s code. These rules are currently still called the priority rules in taxonomy and contain, among others, the following basic agreements:

  • In a species, described independently by multiple authors, only the name published first counts – if it meets the conditions – as the valid name. One of those conditions is that it must be a scientific (usually in Latin, Greek or Latinised) name which has not been used yet.
  • If a species is placed in a different genus, the species name will remain unchanged.

There is however an exception for the Latin ending, if the grammatical gender of the new genus is different from the old one, this will have to be adjusted. An example of this can be found in the genus Forpus. Lafresnaye described in 1848 Psittacula conspicillata. The grammatical gender of Psittacula is female and hence the species name has the female ending ‘a’ in Latin: conspicillata. When this species was relocated ten years later in the genus Forpus, it became Forpus conspicillatus. The grammatical gender of Forpus is male, hence the species name had to be modified.

Note: if within the new genus there is already a species with that species name, then the species name will have to be changed as well. If there are already one or more alternative species names available by (a) different author(s), then the oldest name would be applicable.

  • In taxonomy literature the name of the describing author, together with the publication year, is often appended to the name: Agapornis fischeri Reichenow 1887. If the species has been described by that author but has since then been moved to a different genus, the name of the author is placed between brackets: Agapornis canus (Gmelin, 1788).

Three small rules which did have quite an impact and shortly afterwards there were different international conferences. In 1889 the first ‘International Congress of Zoology’ was organised in Paris. Here the foundation was laid of what would later become ‘The International Commission on Zoological Nomenclature’ (ICZN). This committee is still active today.

In 1892, during the second ‘International Congress of Zoology’, which took place in Moscow, it was decided to acknowledge the tenth edition of ‘Systema Naturae’, written by the Swedish scientist Carl van Linné, and the accompanying nomenclature as the basis for the ‘Zoological nomenclature’ and hence the basis of taxonomy [3].

Carl van Linné or Carolus Linnaeus (1707-1778) as he is also called, studied medicine and obtained his doctorate in 1735 at the former University of Harderwijk (the Netherlands) in medicine with the thesis Hypothesis nova de febrium intermittentium causa. Afterwards he worked as a scientist in Leiden. The same year he published the first edition of Systema Naturae in which he divided nature into three kingdoms (stone, plant and animal kingdom)

In the tenth edition of this Systema Naturae per Regna Tria Naturae, Secundum Classes, Ordines, Genera, Species, Cum Characteribus, Differentiis, Synonymis, Locis (translated: the system of nature through the three kingdoms of nature, according to the Classes, Orders, Genus, Species, with characteristics, differences, synonyms and places) from 1758 he was the first to use the binominal naming method for living organisms. He described each species in the book using a genus name and a species name. It is therefore the 10th edition of his work Systema Naturae (‘System of nature’) from 1758 which is still the basis of the current classification.

The general classification of the animal kingdom according to Linnaeus is as follows: four classes with red blood (the first four) and two classes with white blood (the last two):

Class I: mammals (Mammalia)

Class II: birds (Aves)

Class III: amphibians (Amphibia)

Class IV: fish (Pisces)

Class V: insects (Insecta or Hexapoda)

Class VI: worms (Vermes)

In birds [Aves] Linnaeus also has a sub classification for parrots which he called Psittacus. Psittacus is derived from the Greek psittacos meaning parrot. Hence at that time he placed all parakeets or parrots within the genus Psittacus.

This is also the edition which contains the first descriptions and classification of Agapornis pullarius. Linnaeus had classified these birds, just like all parakeets, within the genus Psittacus and he called the species pullarius (meaning ‘young bird’ – pullus = young bird, chick).

Because of this decision by the International Congress of Zoology the species names from prior to 1758 were obsolete, likewise the species names from after 1758 which did not meet the stated requirements. From then on there were clear guidelines and things could finally be cleared up.

Since then it is still the case that ‘The International Commission on Zoological Nomenclature’ (ICZN) has an advisory role worldwide and guards the correct use of scientific names for organisms. This organisation is located in London and currently consists of 28 members (mainly taxonomists) from 20 different countries. Their guidelines are published in ‘The International Code of Zoological Nomenclature’ [4].

Up until now there have been four conferences, the last dates from before the turn of the century. The agreements agreed upon during this fourth edition became effective on January 1st 2000. In the meantime the basis has been created step by step for the ‘5th edition of the International Code of Zoological Nomenclature (Code)’ which will occur within a few years [5].

These agreements must always assure that we keep on understanding each other. It is therefore of the utmost importance that these rules, even in our hobby, are respected by everyone.

 

Dirk

References:

[1]           Strickland, Strickland Code of Zoological Nomenclature. 1840.
[2]           H. E. Strickland en B. A. for the A. of Science, Rules for zoological nomenclature. J. Murray, 1878.
[3]           B. Dayrat, “17 Celebrating 250 Dynamic Years of Nomenclatural Debates”, Syst. Naturae 250 Linnaean Ark, p. 185, 2009.
[4]           W. D. . Ride, International code of zoological nomenclature. International Trust for Zoological Nomenclature History Museum, 1999.
[5]           “5th edition Wiki | International Commission on Zoological Nomenclature”. [Online]. Available on: http://iczn.org/content/5th-edition-wiki. [Consulted: 31-mrt-2016].

 

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