Selective breeding
Definition:
• Selective breeding (also known as artificial selection) is the process by which humans choose specific animals or plants to breed together to develop particular phenotypic traits.
Unlike natural selection, where "survival of the fittest" determines which traits are passed on, selective breeding is driven by human preference for utility, aesthetics, or efficiency.
1. The Core Method: Step-by-Step:
To change a population, breeders follow a simple, repeating cycle:
1. Selection: Identify a desirable trait (e.g., faster growth, higher milk yield, or a calm temperament).
2. Mating: Breed only the individuals that show that trait most strongly.
3. Culling: Remove (do not breed) individuals that do not show the trait.
4. Repetition: Repeat this over many generations until the trait is "fixed" in the population.
2. Common Mating Strategies:
Breeders use different "genetic paths" to achieve their goals:
• Inbreeding: Mating close relatives to lock in a trait quickly. This makes the population more genetically uniform (homozygous) but increases the risk of inherited diseases.
• Crossbreeding: Mating two different breeds to combine their best features. This often results in Hybrid Vigor, where the offspring are healthier or more productive than their parents.
3. Key Examples & Impacts