Biological classification

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A hierarchy of important ranks

Biological classification is how biologists group organisms.

The standard classification has its root in the work of Aristotle who came up with a multi-ranked system. A great influence was Carolus Linnaeus, who popularized the idea of giving each animal or plant species a two-part name, with one part indicating the genus, and the second part the species. The human species is named Homo sapiens. Names of species are often printed in italics, although there is no obligation to do so (this also goes for names of genera, etc, etc)

Biological classification is also known as taxonomy. It is a science, and like most sciences has evolved over time. At various times different principles were adopted, and it is not rare for different scientists to use different methods. Since about a century, groupings are supposed to fit the Darwinian principle of common descent. These days, molecular evolution studies, which use DNA sequence analysis as data, are popular. This is often called "phylogenetics", a branch or form of cladism. This approach creates a tree of evolution, and uses characters (traits) to decide on the branches of the taxonomy.

Sometimes organisms placed in the same group (taxon) are similar; such similarity is not necessarity coincidence. It may be the result of shared descent from a common ancestor.[1]

Homologous traits are separated from traits that are analogous. For example, birds and bats both have the power of flight, but this is not used to classify them together, 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 the present system of naming living things was developed, Latin was the language most widely used around the world. So, such names are still in Latin. The official descriptions and diagnoses of new taxa in Latin were and are written in Latin as well. Zoologist allow any language for the description of animals. From January 1, 2012, new taxa of algae, fungi and plants may be described in either English or Latin.[2]

Terminations of names[change | change source]

Taxa above the genus level are often given names based on a "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

Related pages[change | change source]

References[change | change source]

  1. 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.
  2. Higgins, Adrian (January 19, 2012). "Veni, vidi, vici – and now history". Washington Post. p. A1.