Humans have bred food crops from wild plants and domesticated animals for thousands of years.
Selective breeding is when humans breed plants and animals for particular genetic characteristics so that they are different to their actual wild ancestors and are now beneficial to humans.
Darwin wondered if a similar process could happen naturally to produce new species through natural selection. In selective breeding characteristics are chosen by humans rather than the environment, so it is sometimes called artificial selection.
Selective breeding takes place over many generations. The main steps for both plants and animals involve:
The new varieties may be economically important. For example, they may provide more or better quality food, or allow farmers to feed more people. Farmers selectively breed different types of cows in order to produce the best meat and dairy products.
A wide range of characteristics can be chosen for usefulness or appearance.
Desired characteristics in plants:
Desired characteristics in animals:
Selective breeding leads to future generations of selectively bred plants and animals, all sharing very similar alleles which will reduce variation. Genes and their different alleles within a population are known as its gene pool. Inbreeding can lead to a reduced range of alleles in the gene pool, making it more difficult to produce new varieties in the future. It also makes organisms prone to certain diseases or inherited defects.