Virus classification

Virus classification is the process of naming viruses and placing them into a taxonomic system. Similar to the classification systems used for cellular organisms, virus classification is the subject of ongoing debate and proposals. This is mainly due to the pseudo-living nature of viruses, which is to say they are non-living particles with some chemical characteristics similar to those of life. As such, they do not fit neatly into the established biological classification system in place for cellular organisms.

Viruses are mainly classified by phenotypic characteristics, such as morphology, nucleic acid type, mode of replication, host organisms, and the type of disease they cause. Currently, two main schemes are used for the classification of viruses: the International Committee on Taxonomy of Viruses (ICTV) system and Baltimore classification system, which places viruses into one of seven groups. Accompanying this broad method of classification are specific naming conventions and further classification guidelines set out by the ICTV.

Species

In biology, a species (abbreviated sp., with the plural form species abbreviated spp.) is one of the basic units of biological classification and a taxonomic rank. A species is often defined as the largest group of organisms where two individuals are capable of reproducing fertile offspring, typically using sexual reproduction. While in many cases this definition is adequate, the difficulty of defining species is known as the species problem. For example, a species complex is a group of closely related species that are very similar in appearance to the point that the boundaries between them are often unclear. Differentiating measures include similarity of DNA, morphology, or ecological niche. Presence of specific locally adapted traits may further subdivide species into "infraspecific taxa" such as subspecies (and in botany other taxa are used, such as varieties, subvarieties, and formae).

Species hypothesized to have the same ancestors are placed in one genus, based on similarities. The similarity of species is judged based on comparison of physical attributes, and where available, their DNA sequences. All species are given a two-part name, a "binomial name", or just "binomial". The first part of a binomial is the generic name, the genus to which the species belongs. The second part is either called the specific name (a term used only in zoology) or the specific epithet (the term used in botany, which can also be used in zoology). For example, Boa constrictor is one of four species of the Boa genus. While the genus gets capitalized, the specific epithet does not. The binomial is written in italics when printed and underlined when handwritten.

Species (disambiguation)

Species is one of the basic units of biological classification.

Species may also refer to:

Films

Other

See also

Octave species

In early Greek music theory, an octave species (εἶδος τοῦ διὰ πασῶν, or σχῆμα τοῦ διὰ πασῶν) is a sequence of incomposite intervals (ditones, minor thirds, whole tones, semitones of various sizes, or quarter tones) making up a complete octave (Barbera 1984, 231–32). The concept was also important in Medieval and Renaissance music theory.

Ancient Greek theory

Greek theorists used two terms interchangeably to describe what we call species: eidos (εἶδος) and skhēma (σχῆμα), defined as "a change in the arrangement of incomposite [intervals] making up a compound magnitude while the number and size of the intervals remains the same" (Aristoxenus 1954, 92.7–8 & 92.9–11 (da Rios), translated in Barbera 1984, 230). Cleonides (the Aristoxenian tradition) described (in the diatonic genus) three species of diatessaron, four of diapente and seven of diapason. Ptolemy in his "Harmonics" called them all generally "species of primary consonances" (εἴδη τῶν πρώτων συμφωνιῶν). Boethius, who inherited Ptolemy's generalization under the term "species primarum consonantiarum" (Inst. mus. IV,14), expanded species theory of Greeks; along with the traditional orderings of three primary species he introduced three further their orderings (Boethius 1989, 149). For epistemology of the Antiquity music theory, the most important of all was the octave species, because "from the species of the consonance of the diapason arise what are called modes" (Boethius 1989, 153).