VariationSpec 4.6.2.1
Differences in the characteristics of individuals in a population are called variation. Variation may be due to differences in:
- the genes they have inherited (genetic causes)
- the conditions in which they have developed (environmental causes)
- a combination of genes and the environment.
The phenotype of an organism develops from its genome and the way the genome interacts with the environment.
| Cause | Examples |
|---|---|
| Genetic | Eye colour, blood group |
| Environmental | A scar from an injury; a plant that grows poorly in poor soil |
| Both | Body mass or height: genes set a potential, but diet and lifestyle affect what is reached |
Mutations
There is usually extensive genetic variation within a population of a species. All variants arise from mutations. Of these:
- most have no effect on the phenotype
- some influence the phenotype
- very few determine the phenotype.
Mutations occur continuously. Very rarely a mutation leads to a new phenotype. If the new phenotype is suited to an environmental change, it can lead to a relatively rapid change in the species.