6.2.3 Selective Breeding

This has been happening for many years since animals were domesticated and plants were grown for food.

• Parents with desired characteristics are chosen.
• They are bred together.
• From the offspring those with desired characteristics are bred together.
• The process is repeated many times until all the offspring have the desired characteristic.

The problem is that it can lead to inbreeding.

• Breeding those with similar desirable characteristics means it is likely you are breeding closely related individuals.
• This results in the reduction of the gene pool, as the number of different alleles reduce (as they mostly have the same alleles).
• This means if the environment changes or there is a new disease, the species could become extinct as they all have the same genetic make-up (so the chance of a few organisms having a survival advantage and not dying is reduced).

Another problem is that the small gene pool leads to a greater chance of genetic defects being present in offspring, as recessive characteristics are more likely to present.