Selective breeding

Humans can increase a desirable inherited feature in a population of plants or animals by choosing which individuals reproduce. This is called selective breeding, or artificial selection. The feature must be inherited so that it can be passed from parents to offspring.

Selective breeding across generations

For example, a grower might want crop plants with larger fruits. The process is repeated over several generations:

1. Identify the feature to improve: fruit size.
2. Choose parents that show the feature: plants with large fruits.
3. Cross the parents to produce offspring.
4. Select offspring that produce large fruits and cross them as parents of the next generation.
5. Repeat the selection and crossing over many generations.

Offspring do not all have exactly the same features, so the grower selects those that best show the desired feature each time. Over generations, large fruit size can become more common in the crop population.

The same approach can be used to increase desirable inherited features in domesticated animals: humans choose parents that show a desired feature, then repeatedly select and breed offspring that also show it.

Selective breeding for food production

Crop plants and farm animals can differ in inherited characteristics that affect how much food they produce. For example, some crop plants produce more edible material, while some dairy cattle produce more milk.

In selective breeding, farmers choose plants or animals with a desirable inherited characteristic to be parents of the next generation. Some of their offspring inherit the characteristic. Farmers then select the most productive offspring to breed again.

By repeating this selection over many generations, the desirable characteristic becomes more common in the population. As a result, the crop or livestock can produce more food. The improvement is gradual: selecting productive parents increases the chance of productive offspring, but does not guarantee that every offspring will be equally productive.