Variation and Mutation

Variation

The behaviour shown by each and every individual organism is different from one to another. Every organism in the universe show variation among themselves. Even the identical twins of the same parents differ in some or more aspects. A morphological or a physiological change in organisms due to either genetic or environmental reasons is said to be variation. 

The variation can be: somatogenic or blastogenic. Somatogenic variation are those variation which is acquired due to the influence of the environment. These variations are not inherited from the parents to offsprings. For example: Development of muscles in an athlete, loss of leg in an accident, etc. Blastogenic variation are those that arises due to the changes in the germ cells which are inheritable for parents to their offsprings. For exampe: colour of skin, hair, eyes, etc.

Similarly, variation can also be classified as continuous and discontinous variations. The variation in which there is possibility of intermediate character is said to be continuous variation. The case in which there is the possibility of different heights between very tall and very short persons can be considered to be an example of continuous variation. It is highly influence by the environment condition and food. It needs a large number of chromosomes to control this type of variations. The variation in which there is no possibility of intermediate character is said to be discontinuous variation. As we have particular gender (except some adnormality), particular blood group and specific finger prints, it is due to discontinuous variations. It is not influenced by environment and food. A very less number of alleles control this variation.

Mutation

A sudden chromosomal change through which a new and distinct character from parents is seen in their offsprings is known as mutation. For example: six fingered limb, disability by birth, special birth mark or character, etc. It can be found in every living beings. Those organisms who are victims of mutation are called mutants and the cause which is responsible for mutation to happen such as radioactive rays, different chemical, etc. are called mutagen. 

Hugo De Vries, a Dutch biologist, is the one who has introduced the concept of mutation in 1907 AD.