6.15 Selective Breeding

Selective breeding is when you take your best plants / animals in your population & breed them together in hopes of getting even better offspring

Selective breeding used for:

  • Cows - meat / milk

  • Crops - resistant to disease

  • Pets - friendly pets

  • Plants - large / unusual flowers

How it works

  1. Select organism with most desirable characteristics that you’re after

  2. Breed these chosen organisms to produce next generation which hopefully contains even better organisms

  3. This process is repeated continuously to produce big beneficial changes in the organism

Drawbacks

  • selective breeding reduces the gene pool of the population

    • (Collection of all different alleles in a population)

    • selective breeding is selecting for certain alleles that code for traits we want

    • As selective breeding is repeated, we get a smaller pool of alleles each time as we get rid of the bad alleles & only keep good ones

  • Best individuals are closely related, so breeding them together can sometimes lead to inbreeding

    • Inbreeding makes offspring more prone to disease or inherited defects due to such small gene pool

  • Small gene pool means less variation within a population

    • so if a new disease came along & infected 1 organism in a population, it’s likely to infect the rest (& lose entire crop)