TAXONOMY

It is the study of rules, principle and practice of classification, identification and nomenclature of an organism. The term was coined by de candolle. Carolus Linnaeus  is known as the Father of taxonomy. Taxonomic studies are based on the comparative study of morphology, cytology, embryology, molecular biology, etc.

This gives the information about the similarities, dissimilarities and evolutionary relationship.

PHYLOGENY

It is the evolutionary history or lineage of one or more groups of organisms. It is based on the study of fossils, comparative anatomy and other fields of study.

SYSTEMATIC

The science which deals with identification, description, classification and nomenclature based on unique properties of every species and group of species at every level of classification. The term was coined by C.Linnaeus. It is often interchangeable with taxonomy.

PROCESSES BASIC TO TAXANOMY

There are four basic processes of taxonomy- characterization, identification, classification, and nomenclature.

1.      All the morphological and other characters of the organism are described.

2.      On the basis of characteristics described, the placement of the organism in various texa is studied.

3.      Taxa connected with the characterization of the organism are than arranged according to a system of classification.

4.      After placing the organism in various taxa of a system of classification, the correct name of the organism or nomenclature is found out.

CLASSICAL OR OLD TAXONOMY (SYSTEMATIC)

In this taxonomy it is considered that the species are immutable (unchangeable) and as per “plan of the creator”. This concept was followed upto days of Linnaeus and his follower.

Classical taxonomy believes that

1.      Species is the basic unit and center of taxonomy. Subspecies varieties and races are not important.

2.      A species is separated on the basis of morphology.

3.      Study of one or few individuals can give information of all the traits of the species. It is often called typological concept.

4.      Species are described on the basis of one or few preserved character.

5.      Species do not change with time. They are static or fixed entities.

6.      Only a few or superficial characters are considered for classification of organisms. This lead to the development of artificial system of classification.

However with ongoing new discoveries there was increase in the knowledge about the organisms, so more and more characters were used for to bring out the natural similarities. As a result the artificial system was replaced by the natural and phylogenetic system of classification. This begins the era of modern taxonomy.

MODERN TAXONOMY (NEW SYSTEMATIC)

In this concept of taxonomy it is considered a species to be product of evolution. It takes evidences from all type of studies like morphology, anatomy, cytology, physiology, genetics, biochemistry, etc. The concept was developed by Julian huxely. It believes that

1.      A large number of individuals are studied to know all the variation.

2.      Population, race, varieties and subspecies are studied thoroughly. Due this it is also called as population systematic.

3.      Evidences from all fields of study are gathered before separating a species.

4.      The naming of species is important but it is not discussed much.

5.      Species are not isolated. They are related amongst themselves by common descent (ancestor).

6.      Morphological delimitation is replaced by biological delimitation in which various branch of systematic are given due importance e.g. cytotaxonomy, morphotaxonomy, chemotaxonomy, etc.