Biological classification
Biological classification is how biologists group organisms.
The standard classification has its root in the work of Carolus Linnaeus, who grouped species according to shared physical characteristics. He invented the idea of giving each animal or plant two names, a genus, and a species. We are described as Homo sapiens. It is always printed in italics like that, and no other way.
These groupings have been revised to fit the Darwinian principle of common descent. Molecular evolution studies, which use DNA sequence analysis as data, has driven many recent revisions, and will continue to do so. Biological classification is a product of taxonomy.
The similarity between organisms placed in the same group or taxon is not arbitrary. It is a result of shared descent from their nearest common ancestor. So, the important attributes or traits for biological classification are those which are 'homologous'. That means they are inherited from common ancestors.[1]
Homologous traits are separated from traits that are analogous. Thus birds and bats both have the power of flight, but this is not used to classify them into a taxon, because it is not inherited from a common ancestor.
In spite of all the other differences between them, the fact that bats and whales both feed their young on milk is one of the features used to classify both as mammals, since it was inherited from a common ancestor.
When people started naming species, Latin was the language most widely used around the world. So, all species names are still Latin names. Scientists used to write the official description of each new species in Latin as well. Years ago, zoologist switched from Latin to English for the description of animals. On January 1, 2012, the International Botanical Congress switched to English for describing new plant species.[2]
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Terminations of names [change]
Taxa above the genus level are often given names based on the main ('type') genus, with a standard termination. The terminations used in forming these names depend on the kingdom, and sometimes the phylum and class, as set out in the table below.
| Rank | Plants | Algae | Fungi | Animals |
|---|---|---|---|---|
| Division/Phylum | -phyta | -mycota | ||
| Subdivision/Subphylum | -phytina | -mycotina | ||
| Class | -opsida | -phyceae | -mycetes | |
| Subclass | -idae | -phycidae | -mycetidae | |
| Superorder | -anae | |||
| Order | -ales | |||
| Suborder | -ineae | |||
| Infraorder | -aria | |||
| Superfamily | -acea | -oidea | ||
| Family | -aceae | -idae | ||
| Subfamily | -oideae | -inae | ||
| Tribe/Infrafamily | -eae | -ini | ||
| Subtribe | -inae | -ina | ||
Cladism [change]
An important alternative approach to biological classification is cladism. This approach is based on the branching tree of evolution. It uses characters (traits) to decide on the branches of the taxonomy.
Related pages [change]
- Taxonomy
- Systematics
- Cladistics
- Molecular evolution
- Molecular clock
- Wastebasket taxon
- Evolutionary grade
References [change]
- ↑ Mayr, Ernst; Bock, W.J. (2002). "Classifications and other ordering systems". J. Zool. Syst. Evol. Research 40 (4): 169–94. doi:10.1046/j.1439-0469.2002.00211.x.
- ↑ Higgins, Adrian (January 19, 2012). "Veni, vidi, vici – and now history". Washington Post. p. A1.
