Selective Breeding

Selective breeding is when humans artificially select the plants ot animals that are going to breed so that the genes for particular characteristics remain in the population.

Organisms are selectively bred to develop features that are useful or attractive.

For Example:

- Animals that produce more meat or milk

- Crops with disease resistance

- Dogs with a good, gentle temperament

- Decorative plants with big or unusual flowers

1) From existing stock, select ones which have the desired characteristics

2) Breed them with eachother

3) Select the best of the offspring and breed them together

4) Continue this process over several generations, and the desireable trait gets stronger and stronger. Eventually all the offspring will have the characteristic

• Reduces the gene pool -> the number of different alleles in a population

-> farmer keeps on breeding the "best" animals or plants - which are all closely related

-> known as inbreeding

• Inbreeding can cause health problems

-> more chance of organisms inheriting harmful genetic defects when the gene pool is limited

• Serious problems if a new disease appears

-> not much variation in the population

-> all stock are closely related to eachother (one is going to be killed, others likely to)

Selective breeding -> Reduction in the number of different alleles -> Less chance of any resistant gene being present in the population