In natural selection, the environment determines which traits are advantageous, leading to species that are well adapted to their environment.

In artificial selection, humans choose the traits, focussing on enhancing one or two characteristics and leading to species that are beneficial to humans in some manner.

Artificial selection (selective breeding) is the process by which humans breed organisms for specific genetic traits and determine which individuals reproduce.

Artificial selection changes allele frequencies by favouring certain traits, leading to these traits becoming more common over time.

Artificial selection is done to enhance desired traits in organisms. This produces a population of individuals that all show the desired characteristics and can be interbred to produce offspring with these characteristics.

For instance, breeders may want to breed horses that can run fast or cattle that produce more milk.

1. Select a population showing variation
2. Select individuals with desired traits
3. Breed these individuals together
4. Grow and test the offspring
5. Repeat this process until the desired traits are achieved

Inbreeding is the process of breeding closely related individuals.

An advantage of inbreeding is that it can be used in artificial selection to preserve desirable traits.

A disadvantage of inbreeding is that it limits genetic diversity and increases homozygosity and so the chance of harmful recessive alleles being expressed. This leads to inbreeding depression, which is a loss of the ability to survive and grow well.

For example, maize plants with inbreeding depression become progressively smaller.

Outbreeding is the process of breeding unrelated or distantly related individuals.

An advantage of outbreeding is that it can lead to hybrid vigour, an increased ability to survive and grow well due to increased heterozygosity, reducing the occurrence of harmful recessive traits.

For example, hybrid vigour in maize plants makes them healthier, grow taller, and produce higher yields.

1. To produce many different varieties of rice and wheat
2. To produce wheat grains that are rich in gluten
3. To produce varieties that have resistance to diseases like those caused by fungal infection

Seed banks store seed samples from wild-type and domestic varieties.

Gene banks store biological samples such as sperm or egg cells.

Wild-type alleles are those that code for the most normal or common characteristic.

Wild-type alleles from gene banks, seed banks, or the wild can be used in outbreeding, which can increase the genetic diversity after it is reduced with inbreeding. This reduces the frequency of recessive alleles that may be harmful, and increases the ability of populations to adapt to environmental change.

Ethical issues with artificial selection include the limited gene pool and low genetic diversity that is introduced to these organisms with inbreeding. This can result in many homozygous recessive traits that can be harmful.

For instance, many pedigree dog breeds experience specific health issues, like heart, brain, respiratory, or spinal problems.