Question

What are the different types of variations?

Answer 1

Hint: Variation in the phenotype is caused either by the environment o, by the Genetics or by the combination of the two. Meiosis and sexual reproduction introduces variation.

Complete Answer:
Variation, the small differences that exist between individuals, can be described as being either discontinuous and continuous.

Discontinuous variation: This is where individuals fall into a number of distinct classes or categories, and is based on features that cannot be measured across a complete range.
- Someone either has the characteristic or not, example blood group. A person can have one blood group or another, it can't be a between.
- Discontinuous variation is either controlled by alleles of a single gene or small number of genes. The environment has little effect on this type of variation.

Continuous variation: In continuous variation, there is a complete range of measurement from one extreme to another. Height is an example of the continuous variation. Individuals can have a complete range of height, for example 1.60, 1.61, 1.62 etc.
- Continuous variation is a combined effect of many genes known as polygenic inheritance and is obtained significantly affected by environmental influences.
- Milk yield in cows, for example, is determined not only by their genetic makeup but is also significantly affected by the environmental factors such as partial quality and diet, weather and the comfort of their surroundings.

Note: The direction of the continuous variation is predictable. The direction of the discontinuous variation is unpredictable discontinuous variations are produced by changes in the genome or genes. And continuous variation is formed due to chance segregation chromosome during gamete formation crossing over and chance pairing during fertilization.