Discontinuous and Continuous Variations

The inheritable variations are of two types i.e. discontinuous and continuous variations.

Discontinuous variations show distinct phenotypes. The phenotypes of such variations cannot be measured. The individuals of a population either have distinct phenotypes, which can be easily distinguished from each other. Blood groups are a good example of such variations. In a human population, an individual has one of the four distinct phenotypes and cannot have in between. Discontinuous variations are controlled by the alleles of a single gene pair. The environment has title effect on this type of variations.

In continuous variations, the phenotypes show a complete range of measurements from one extreme to the other. Height, weight, feel size, intelligence etc. Are example of continuous variations. In every human population, the individuals have a range of heights. No population can show only two or three distinct heights. Continuous variations are controlled by many genes and are often affected by environmental factors.