How are variations classified?

Explanation

Type of variations:
(i)Somatic variation :These are the variations which affect the body (Somatic) Cells of the organisms.They are not herbitable.They occur due to environmental factors.
(ii)Germinal variation:These variations are produced in germ cells of an organism.They are inherited.They may be present in ancestors or may occur suddenly.They are classified into two types:
1. Continuous variation
2. Discontinuous variation.
1.Continuous variation:
(i)These are small variations which occur among individuals of a population.They are also called as Fluctuating variations.
(ii)They occur by gradual accumulation in a population. E.g: skin colour,height and wieght of an individual,colour of eye,etc.
2.Discontinuous variations:
(i)These are sudden changes which occurs in an organism due to mutation.They do not have any intermediate forms.
(ii)These large variation are not useful for evolution E.g: short legged Ancon Sheep,six or more digits (fingers) in human,etc.
(iii)Discontinuous variation form the basis for Mutation theory proposed by De Vries.