Selective Breeding — AQA GCSE Biology

Selective breeding (artificial selection) is how humans have bred plants and animals for desired characteristics for thousands of years.

What is selective breeding?

Selective breeding is the process by which humans breed plants and animals for particular desired characteristics:

1. Choose parents with the desired characteristic from a mixed population.
2. Breed them together.
3. From the offspring, choose those with the desired characteristic and breed them.
4. Repeat over many generations until all offspring show the desired trait.

Examples of desired characteristics

• Animals that produce more meat or milk.
• Disease resistance in food crops.
• Domestic dogs with a gentle nature.
• Large or unusual flowers.

Problems with selective breeding

• It reduces variation (the gene pool), because only a few individuals are bred.
• This can lead to inbreeding, where some breeds are more prone to disease or inherited defects.
• Reduced variation also means the population may not cope well with new diseases or environmental change.

Comparison with natural selection

Selective breeding is similar to natural selection, but humans choose which organisms reproduce (based on usefulness to us) rather than the environment.

Exam tips

• Describe the repeated process of choosing and breeding over many generations.
• Give examples of desired characteristics.
• Explain the main problem: reduced variation → inbreeding → disease/defects.
• Compare it with natural selection (humans choose vs environment selects).