Linnean taxonomy

From Palaeos.org

Jump to: navigation, search
m (Taxonomic Inflation: moved bottom template)
m (Protected "Linnean taxonomy" ([move=sysop] (indefinite)))
 
Line 1: Line 1:
-
{{systematics}}
+
{{Taxonomy}}
==The Linnaean Hierarchy==
==The Linnaean Hierarchy==
-
The Linnaean taxonomy is a formal system for classifying and naming living things based on a simple hierarchical structure, from most general to most similar  The basic hierarchy as formulated by Linneus, is as follows:
+
The Linnaean taxonomy is a formal system for classifying and naming living things based on a simple hierarchical structure, from most general to most similar  The basic hierarchy as formulated by [[Carolus Linnaeus|Linnaeus]], is as follows:
* Imperium ("Empire") - the phenomenal world  
* Imperium ("Empire") - the phenomenal world  
Line 86: Line 86:
|''[[Escherichia coli|E. coli]]''
|''[[Escherichia coli|E. coli]]''
|}
|}
-
 
==What's in a name?==
==What's in a name?==
-
The formal international agreement on names, ranks, and so on, is laid out in the [[International Code of Zoological Nomenclature]], the [[International Code of Botanical Nomenclature]], and the [[Bacteriological Code of Nomenclature]].  These set guidelines and publish a reports containing the rules of nomenclature.  For example, the Law of Priority (Article 25) says that if a genus or species has been accidentally given two names, only the earlier one is valid.  The later name becomes a "junior synonym".  This is the case even when it is better known (or more evocative).  To give a famous illustration, the Jurassic dinosaur ''Brontosaurus'', named by the 19th century American paleontologist Othniel C. Marsh in 1879, was later found to be the same animal as ''Apatosaurus'', which was actually named by the same guy two years previously (this was during the great dinosaur rush when Marsh and his rival Edward Drinker Cope were engaged in a bitter feud to see who could discover the most prehistoric animals!).  Therefore ''Apatosaurus'' is the correct name, even though "thunder lizard" (''Brontosaurus'') would seem more appropriate than "deceptive lizard" (''Apatosaurus''), and even though the later name honors the same man (maverick paleontologist Dr Bob Bakker has suggested using ''Brontosaurus'' anyway!).  A similar thing happened with ''Eohippus'' ("dawn horse") and ''Hyracotherium'' ("hyrax beast").  The better known, more appropriate name was later fond to be describe the same animal as had been previously named.  In some cases things are not so clear cut, and a ruling from the Commission in charge of these things is necessary to decide which name to use.
+
The formal international agreement on names, ranks, and so on, is laid out in the [[International Code of Zoological Nomenclature]], the [[International Code of Botanical Nomenclature]], and the [[Bacteriological Code of Nomenclature]].  These set pseudo-legal rules and publish a reports containing the rules of nomenclature.  For example, the Law of Priority (Article 25) says that if a genus or species has been accidentally given two names, only the earlier one is valid.  The later name becomes a "junior synonym".  This is the case even when it is better known (or more evocative).  To give a famous illustration, the Jurassic dinosaur ''Brontosaurus'', named by the 19th century American paleontologist Othniel C. Marsh in 1879, was later found to be the same animal as ''Apatosaurus'', which was actually named by the same guy two years previously (this was during the great dinosaur rush when Marsh and his rival Edward Drinker Cope were engaged in a bitter feud to see who could discover the most prehistoric animals!).  Therefore ''Apatosaurus'' is the correct name, even though "thunder lizard" (''Brontosaurus'') would seem more appropriate than "deceptive lizard" (''Apatosaurus''), and even though the later name honors the same man (maverick paleontologist Dr Bob Bakker has suggested using ''Brontosaurus'' anyway!).  A similar thing happened with ''Eohippus'' ("dawn horse") and ''Hyracotherium'' ("hyrax beast").  The better known, more appropriate name was later found to be describe the same animal as had been previously named.  In some cases things are not so clear cut, and a ruling from the Commission in charge of these things is necessary to decide which name to use.
-
The complete scientific name includes genus and species, the name of the scientist who first described the species in a scientific journal deemed valid for taxonomic purposes, and the year that the paper was published.  By convention that the genus and species are written in italics (or, where that is not possible, underlined, or even _underlined ascii wise_).  The generic name is always capitalized, the trivial or species name is not.  So we have (to use the above illustration) ''Apatosaurus ajax'' Marsh, 1877
+
The complete scientific name includes genus and species, the name of the scientist who first described the species in a scientific journal deemed valid for taxonomic purposes, and the year that the paper was published.  By convention that the genus and species are written in italics (or, where that is not possible, underlined, or even _underlined ascii wise_).  The generic name is always capitalised, the trivial or species name (epithet) is not.  So we have (to use the above illustration) ''Apatosaurus ajax'' Marsh, 1877
When a species is placed in a genus different to the one originally named, then the discoverer's name is placed in brackets, even when it is the same guy who named both.  So ''Brontosaurus excelsus'' Marsh, 1879 becomes ''Apatosaurus excelsus'' (Marsh, 1879)
When a species is placed in a genus different to the one originally named, then the discoverer's name is placed in brackets, even when it is the same guy who named both.  So ''Brontosaurus excelsus'' Marsh, 1879 becomes ''Apatosaurus excelsus'' (Marsh, 1879)
Line 206: Line 205:
* Higher taxa and especially intermediate taxa are prone to revision as new information about relationships is discovered. For example, the traditional classification of primates (class Mammalia — subclass Theria — infraclass Eutheria — order Primates) is challenged by new classifications such as McKenna and Bell (class Mammalia — subclass Theriformes — infraclass Holotheria — order Primates). See [[Mammalia classification]] for a discussion. These differences arise because there are only a small number of ranks available and a large number of branching points in the fossil record.
* Higher taxa and especially intermediate taxa are prone to revision as new information about relationships is discovered. For example, the traditional classification of primates (class Mammalia — subclass Theria — infraclass Eutheria — order Primates) is challenged by new classifications such as McKenna and Bell (class Mammalia — subclass Theriformes — infraclass Holotheria — order Primates). See [[Mammalia classification]] for a discussion. These differences arise because there are only a small number of ranks available and a large number of branching points in the fossil record.
-
* Within species further units may be recognised. Animals may be classified into [[subspecies]] (for example, ''Homo sapiens sapiens'', modern humans) or [[morph]]s (for example ''Corvus corax varius'' morpha ''leucophaeus'', the Pied Raven). Plants may be classified into subspecies (for example, ''Pisum sativum'' subsp. ''sativum'', the garden pea) or varieties (for example, ''Pisum sativum'' var. ''macrocarpon'', snow pea), with cultivated plants getting a [[cultivar]] name (for example, ''Pisum sativum'' var. ''macrocarpon'' 'Snowbird'). Bacteria may be classified by [[strain]] (for example Escherichia coli O157:H7, a strain that can cause food poisoning.
+
* Within species further units may be recognised. Animals may be classified into [[subspecies]] (for example, ''Homo sapiens sapiens'', modern humans), variants (for example ''Dakosaurus maximus'' var. ''gracilis'', gracile form of a fossil marine crocodilian) or [[morph]]s (for example ''Corvus corax varius'' morpha ''leucophaeus'', the Pied Raven). Plants may be classified into subspecies (for example, ''Pisum sativum'' subsp. ''sativum'', the garden pea) or varieties (for example, ''Pisum sativum'' var. ''macrocarpon'', snow pea), with cultivated plants getting a [[cultivar]] name (for example, ''Pisum sativum'' var. ''macrocarpon'' 'Snowbird'). Bacteria may be classified by [[strain]] (for example Escherichia coli O157:H7, a strain that can cause food poisoning.
== Terminations of names ==
== Terminations of names ==
Line 295: Line 294:
:[[Goege Gaylord Simpson|G.G. Simpson]], "The Principles of Classification and a Classification of Mammals", Bulletin of the American Museum of Natural History, vol.85, (New York, 1945) p.23  
:[[Goege Gaylord Simpson|G.G. Simpson]], "The Principles of Classification and a Classification of Mammals", Bulletin of the American Museum of Natural History, vol.85, (New York, 1945) p.23  
-
One thing the codes of nomenclature are unable to do anything about is personal preference as to how to divide up families, genera etc.  Here we have the famous disagreement between the splitters and the lumpers, between those who prefer to lump together a large number of species in each genus, or genera in families, and those who would rather split genera among new families, and put species in new genera.  Hence among, say, malacologists (those who study molluscs), there is on the one hand those who would lump all species of cone shells in the old traditional genus Conus, and those who would divide them up among a large number genera - Lithoconus, Floraconus, Parviconus, etc etc.  This can be very annoying for amateur naturalists who would like to have the right name for their labels!
+
One thing the codes of nomenclature are unable to do anything about is personal preference as to how to divide up families, genera etc.  Here we have the famous disagreement between the splitters and the lumpers, between those who prefer to lump together a large number of species in each genus, or genera in families, and those who would rather split genera among new families, and put species in new genera.  Hence among, say, malacologists (those who study molluscs), there is on the one hand those who would lump all species of cone shells in the old traditional genus ''Conus'', and those who would divide them up among a large number genera - ''Lithoconus'', ''Floraconus'', ''Parviconus'', etc etc.  This can be very annoying for amateur naturalists who would like to have the right name for their labels!
The situation becomes even more involved with the large degree of arbitrariness with these finer sub-rankings due to personal preference and bias.  One man's superfamily may be another man's suborder!
The situation becomes even more involved with the large degree of arbitrariness with these finer sub-rankings due to personal preference and bias.  One man's superfamily may be another man's suborder!

Latest revision as of 20:09, 16 January 2012

Personal tools