discontinuous variation

genetics

Also known as: qualitative variation

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June 25, 2026

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Discontinuous variation in biology refers to abrupt variations within a species where there are few or no intermediate forms. This is in contrast to continuous variation, which shows a smooth grading between two extremes, with most individuals falling near the average.12

Discontinuous variations are distinct and easily categorized, such as human blood groups. These variations are typically caused by differences in the number or structure of chromosomes, or by variations in the genes they carry. While genotypic variations are inheritable, environmentally caused variations do not involve hereditary alterations and are not passed to future generations. Discontinuous traits are determined by single genes with major effects, unlike quantitative traits which are polygenic, meaning they are influenced by multiple genes and environmental factors.23

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variation
…in human populations); or as discontinuous, or qualitative (composed of well-defined classes, as blood groups vary in humans). A discontinuous variation with several classes, none of which is very small, is known as a polymorphic variation. The separation of most higher organisms into males and females and the occurrence of…
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…in human populations); or as discontinuous, or qualitative (composed of well-defined classes, as blood groups vary in humans). A discontinuous variation with several classes, none of which is very small, is known as a polymorphic variation. The separation of most higher organisms into males and females and the occurrence of…
Read More