9E: Selective Breeding

Question 1

Selective Breeding/Artificial Selection:

Answer 1

the changing of a populations gene pool due to humans altering the breeding behaviour of animals and plants to develop a selected trait

- Can be used to select for the desirable trait but can also be used to select against an unwanted trait to remove it from a population

• Difference to natural selection is that NS involves a naturally occurring environmental selection pressure(predation, disease or climate change) which select individuals with a selective advantage within their environment

Question 2

Requirements for Selective Breeding:

Answer 2

• Variation: individuals in a population vary genetically, resulting in phenotypic differences
  • Selection Pressures: direct human intervention places an artificial selection pressure upon a population of individuals only allowing certain individuals with desirable traits to breed.
  • Heritability: the trait selected must be heritable, allowing it to be passed on from the parents to their offspring. Selected allele will increase in frequency

Question 3

Effect of Selective Breeding on genetic diversity:

Answer 3

• Can lead to smaller gene pools and the overexpression of deleterious(negative effecting) alleles which reduce the adaptability and fitness within a population
  • Poor breeding practices can cause a human induced genetic bottleneck as by restricting the breeding to individuals with desirable traits means that the generational increase of the selected allele will decrease genetic diversity
  • Reduced genetic diversity can result in increased inbreeding, therefore increasing the prevalence of deleterious alleles and have a lower adaptive potential