Manipulation of gene pools
Humans have been altering the gene pools of domesticated species since transitioning from a hunter-gatherer society to an agricultural society. This process is known as selective breeding, or artificial selection, where only organisms with desirable traits are chosen to reproduce.
Unlike natural selection , selective breeding involves humans intervening and selecting the most desirable trait or phenotype for their purposes. This process occurs over generations, increasing the number of individuals with the trait and potentially leading to its becoming fixed in frequency.
The image below highlights one example of how humans have bred food crops from wild plants. The wild mustard plant has many desirable traits that are being selected for, over many generations, to create new varieties with different characteristics.
Selective breeding programs
Selective breeding is the process of breeding plants and animals to develop specific traits. For example it can involve breeding:
- animals for increased meat or milk production,
- plants for increased resistance to disease and pests,
- plants to increase crop yield,
- for a particular aesthetic preference, behavioural or functional trait.
Humans have been selectively breeding domestic dogs for over many years, creating hundreds of different breeds based on specific traits, like size or intelligence.
Effects of selective breeding
Benefits of selective breeding include:
- New varieties of plant and animals created
- Increased food quality
- Crop resistance to disease or pesticides
- Increased crop yield
Risks of selective breeding include:
- Reduced genetic variation
- Rare disease genes can be unknowingly selected as part of a positive trait
- Genetic mutations can randomly occur.
