Question

Differentiate continuous variation with a discontinuous variation.

Answer 1

1. Discontinuous Variation: Within a population, there are some characteristics that show a limited form of variation.
   Example: Style length in Primula, plant height of garden pea. In a discontinuous variation, the characteristics are controlled by one or two major genes which may have two or more allelic forms.
   These variations are genetically determined by inheritance factors. Individuals produced by this variation show differences without any intermediate form between them and there is no overlapping between the two phenotypes. The phenotypic expression is unaffected by environmental conditions. This is also called qualitative inheritance
2. Continuous Variation: This variation may be due to the combining effects of environmental and genetic factors. In a population, most of the characteristics exhibit a complete gradation, from one extreme to the other without any break. Inheritance of phenotype is determined by the combined effects of many genes, (polygenes) and environmental factors. This is also known as quantitative inheritance.
   Example: Human height and skin color.