Taxonomy : Systems of classifications

Overview

Taxonomy is the branch of biology which deals with identification, nomenclature and classification pf organisms. 

Nomos- rule

Taxonomy is the branch of biology which deals with identification, nomenclature and classification pf organisms. It is also known as systematics. Systematics deals with the study of living organisms and existing relationship among themselves. It includes classification, identification, nomenclature and biosystematics.

Classification:

It is the arrangement of organisms in definite groups showing their relationship.

Identification:

It is the finding of the correct position of unknown organisms being similar or identical to already known organisms.

Nomenclature:

It is the determination of the scientific name or correct name to all organisms so that they are easily distinguished.

Biosystematics:

Biosystematics deals with the diversity of organisms by comparing grouping of an organism at every rank of classification right from species to the kingdom.

History of Taxonomy

The great Greek philosopher and biologist of 4^thcentury B.C., Aristotle created groups and species. He classified as herbs, shrubs, and trees. Charaka, the father of Ayurveda, classify plants and animals on the basis of their medical importance in the 1^st century. Theophrastus is known as a father of botany. He distinguished the plants on the basis of life spans into three groups i.e. annuals, biennials or perennials plants in the period of 2^nd and 3^rdB.C. John Ry, a British naturalist of late 17^th century introduced 'Natural system of Classification' based on morphological similarities.

The greatest Swedish naturalist of the 18^th century, Carolus Linnaeus is known as the father of taxonomy. He introduced the current system of the naming of organisms with two names. The first name is the generic name and the second name is the specific name. This system of naming plants and animals in two words is known as 'Binomial system of nomenclature'.

Need of Taxonomy

• Study of organisms and research is easier due to taxonomy.
• Taxonomy helps us to show natural relationships among organisms.
• Taxonomy can show the phylogenetic relationship of organisms.

Systems of classifications:

There are mainly three systems of classification. They are:

Artificial system of classification:

In the artificial system of classification, only a few superficial character are considered to group organisms. Eg; classification of Carolus Linnaeus.

Disadvantages :

• In this classification system, dissimilar organisms are kept in the same group and similar organisms are kept in the same group and similar organisms are kept in a different group.
• This classification system cannot show the natural relationship among organisms.
• This classification system cannot show the phylogenetic relationship of organisms.

Natural classification:

The system of classification in which several taxonomy characters are considered to classify the organisms is the natural system of classification.

Taxonomy characters considered in natural system of morphology are as follow:

• Morphology
• Anatomy
• Physiology
• Cytology
• Genetics
• Chemotaxonomy

Advantages :

• In this classification system, dissimilar organisms are kept in a different group and similar organisms are kept in the same group.
• This classification system shows the natural relationship among organisms.
• This classification system can reflect the phylogenetic relationship of organisms.

Eg; Bentham and Hooker's system of classification.

Phylogenetic classification:

Phylogenetic system of classification is that system of classification in which phylogenetic relationship of organisms in addition to sexual taxonomy characters are considered to classify organisms.

Eg; Engler and Prantl's classification

Advantages:

• In this classification system, dissimilar organisms are kept in the different group and similar organisms are kept in the same group.
• This classification system shows the natural relationship among organisms.
• This classification system can reflect the phylogenetic relationship of organisms.