BIOL - Natural Selection vs. Selective Breeding

Frequently asked in IGCSE Biology: comparison of natural selection and selective breeding

Both processes result in genetic changes over time, but there are many differences in how the genetic changes are achieved.

Natural Selection

Natural selection is the key mechanism that is responsible for the evolution of organisms over generations.

This is how natural selection occurs:

1. Individuals in a species show variation in their genes. The variation is due to mutations that occur randomly.
2. Only individuals with characteristics that are fit for the environment will survive and reproduce. This is called survival of the fittest.
3. The allele (or gene) is passed down to the offspring.
4. Since individuals that do not have the genes that are suitable for the environment will be killed, the frequency of suitable alleles in the species will increase over generations.

Selective Breeding

Selective breeding is the method that humans use to improve characteristics of organisms to breed (e.g. cows that produce a lot of milk, disease-resistant crops)

This is how selective breeding occurs:

1. Humans select individuals with desired characteristics. 
2. The selected individuals are bred together.
3. From the offspring, individuals that have the desired characteristics are bred together. 
4. This process is repeated over many generations. 

Comparison of Natural Selection and Selective Breeding

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