6.2 Variation and Evolution

6.2.1 Variation

FSL: GCSE Biology Revision "Variation"

- Variation is a difference in characteristics between individuals of the same species caused by random mutations.
- Genetic variation is caused by different alleles and mutations.
- Environmental variation is caused by the environment / surroundings.

• the genes they have inherited (genetic causes)
• the conditions in which they have developed (environmental causes)
• a combination of genes and the environment.

Natural Selection

- Natural selection is a mechanism of evolution that explains how organisms better suited to their environment are more likely to survive and reproduce.

Discrete Variation

- The data can only be a limited set of value e.g. blood group, eye colour, hair colour.
- Represented by a bar or pie chart.

Continuous Variation

- The data can be any value in a range e.g. height, mass.
- Represented by a scatter graph or histogram.

6 mark answer structure example

_{Explain why male red deer have large antlers}

1. There is a variation of alleles in the population of deer
2. Random mutations give rise to deer with large antlers
3. The environment changes which is a selection pressure
4. Deer with smaller antlers lose more fights so get poorer land / fewer mates so they are more likely to die
5. Deer with bigger antlers are more likely to survive, reproduce, and pass on their large antler alleles
6. Frequency of deer with alleles for larger antlers increases over generations