U4 AOS2 Topic 5: Selective Breeding

Selective breeding is a process by which humans change the breeding behavior of plants and animals to select or remove traits from population.

Requirements of selective breeding:

1.   Variation: individuals in a population varying genetically show phenotypic differences and therefore allow selective breeding. For example, a sheep population has phenotypic variation i.e. low and high wool density.  

2.   Selection pressure: humans allow only certain individuals with desirable traits to breed by placing an artificial selection pressure on a population. For example, the desirable trait i.e. high wool density is selected by allowing the breeding of sheep with high wool density only.

3.   Heritability: the selected desirable traits must be heritable to increase the allele frequency of selected traits in the next population. For example, the wool density is a heritable trait and selection of only high-density wool causes its allele frequency to increase over time.

 

Selective breeding is also known as artificial selection and is almost similar to natural selection but involves artificial selection pressure induced by humans instead of environmental selection pressure.

Selective breeding can cause the allele frequency of only desirable traits to increase forming a smaller gene pool. Selection of only desirable traits can cause the genetic diversity to decrease which leads to lower adaptive potential as the new population cannot adapt to new selection pressure because of smaller gene pool.