Genetic and environmental variationSpec 3.33
Differences between individuals of the same species are called variation. Variation within a species can be genetic, environmental, or a combination of both.
| Genetic variation | Environmental variation | |
|---|---|---|
| What it is | Differences caused by the alleles an organism inherits | Differences caused by an organism's surroundings and way of life |
| Examples | Blood group, eye colour, sex | A scar, body mass affected by diet, plant height affected by light |
Many features are affected by both. For example, a person's height depends on the alleles they inherit and also on their diet when growing up. A plant's height depends on its alleles, and also on the light and minerals it receives.
Exam tip:
Identical twins have the same alleles. Differences between them must be caused by the environment, which is a favourite way of testing this point.