Taxon
From Palaeos
| TAXONOMY |
| Classification | Evolutionary Taxonomy | Linnaean Taxonomy | Nomenclature | Taxonomic inertia |
A taxon (plural taxa), or taxonomic unit, is a grouping of organisms, whether named or unnamed. Once named, a taxon will usually have a rank and can be placed at a particular hierarchical level.
In the case of Linnaean and Linnaean-based taxonomy, the hierarchical ranks areas follows:
- Domain
- Kingdom
- Phylum (animals) or Division (plants, fFungi, and microorganisms)
- Class
- Order
- Family
- Genus
- Species
Prefixes are used to indicate further ranks; for example super- indicates a rank immediately above, and sub- a rank immediately below. infra- indicates a rank below sub-. For instance:
Ranking is often subjective or relative. For example, liverworts have been variously considered a family, order, or a class. Or a higher rank may be goiven to a familiar group of organisms - e.g. orders of birds, then to those that are less familiar but may be equally morphologically distinct - e.g. families or superfamilies of invertebrates. There is also the tendency to taxonomic inflation, whereby a rank of lower staus is accorded progressively higher value - e.g. an order may become a class or even a subphylum.
The use of taxonomic ranks in this manner has been challenged by cladists and has recently led to the development of a PhyloCode, on which ranking is determined purely phylogentically, as nested clades, without use of Linnaean, evolutionary systematic, or phenetic characteristics.
[edit] Credits
MaAK061016 incorporating material from Wikipedia)
