What is Taxonomy

The science of classification is called Taxonomy and it involves the naming of organisms (nomenclature) and the systemic placing of organism into groups or taxa (Systematics) on the basis of certain relationships between organisms. Biological nomenclature is based on the binomial system pioneered by the work of the Swedish naturalist Carl Linnaeus (1707 -78). In this system each organism has two Latin names: a generic name beginning with a capital letter and a specific name beginning with a lower case letter. For example Homo sapiens.

Classification Of Organism:

The binomial system classifies organisms into groups at various hierarchical levels on the basis of easily observable, shared structural features, such as shape, number of, and position of, limbs and so on. It has since been extended, and the main hierarchical taxa now used is this system as follows, in descending order of size.

  • Phylum(Division in plants)
  • Class
  • Order
  • Family
  • Genus
  • Species

Each taxon may contain a number of taxon units below it, for example one phylum may contain six classes or a genus three species, but each taxon can only belong to the single taxon above it, for example an order can only belong to one class above it. Within each hierarchical level there may be several taxa but each is distinct in that whilst the members of each taxon share a common set of diagnostic features also possessed by all organisms at preceding taxonomic levels (higher levels), each taxon possesses diagnostic features unique to that taxon.

Taxa may be further subdivided into subtaxa, such as subclass or grouped together into super taxa, such as superclass. Other taxa may also be formed by splitting taxa into infrataxa or tribes, or grouping taxa into cohorts.

The most natural group of organism is the species and this is the lowest taxon in the Linnean system. Each species possesses its own distinct structural, behavioral and ecological characteristics.

Types of Classification:

There are two types of classification, artificial and natural, an artificial classification is used upon one or a few easily observable characteristics, and is devised and used for limited number of special purposes where convenience and speed are important. A natural classification may be either phylogenetic or phonetic depending upon the criteria on which the classification is based.

The most commonly used form of classification is phylogenetic and it reflects possible evolutionary relationship based on ancestry and descent. In such a system organisms belonging to the same taxa are believed to have a common ancestor, and may be represented in the form of a family tree, in this case called a cladogram.

A phonetic classification is based upon evidence presented by numerical taxonomist who consider masses of data relating to present – day morphological, cytological and biochemical similarities between organisms. This may reflect evolutionary relationship but is not constructed with this in view. A family tree based upon phonetic classification is called a dendrogram.

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