What is variation? (spec 3.33)
Variation is the set of differences between individuals of the same species.
Look around a classroom of people. Everyone is a human being — the same species — yet no two people are identical. Some are taller, some have brown eyes and some blue, some have curly hair and some straight. These differences between individuals of the same species are called variation.
Variation is everywhere in living things. Even kittens from the same litter, or seeds from the same plant, show small differences from one another.
The specification says variation within a species can come from three sources:
- genetic causes (the genes you inherit from your parents),
- environmental causes (the surroundings you live in and the things that happen to you), or
- a combination of both working together.
So when you see a difference between two individuals, the key question is always: is this caused by their genes, by their environment, or by both?
Exam tip. A reliable one-mark answer for "what is meant by variation?" is the differences between individuals of the same species. Adding "of the same species" is what makes the definition fully correct.
- Variation = differences between individuals of the same species.
- It has three sources: genetic, environmental, or both combined.
- Members of one species are never identical to each other.
See the full worked example for variation with a species →