Genetic Diversity - Chapter 9 AQA AS Biology

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  • Created by: H.N
  • Created on: 15-11-12 20:02
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  • Genetic Diversity
    • more alleles
      • could occur due to mutations in the DNA
      • gene flow - migration of organisms
      • can adapt to environment better
      • more genetic diversity
    • selective breeding/artificial selection
      • individuals with desired characteristics  selected for next generation
      • unwanted alleles bred out of population
      • usually to produce high-yielding breeds
      • For
        • high-yields of animals/plants
        • species with increased resistance to disease
          • fewer drugs/pesticides for farmers
        • bred to have increased tolerance to bad conditions
      • Against
        • health problems for animals
        • reduced genetic diversity
        • increased genetic disease
        • increased susceptibility to new diseases due to lack of alleles
    • The founder effect
      • few individuals colonise  a new rehion
      • few alleles - may not represent whole population
      • less alleles to adapt to environment
      • less genetic diversity than previous population
      • more inbreeding - higher incidence of genetic disease
    • Genetic bottlenecks
      • dramatic drop in numbers in a population
      • due to chance event or human interference
      • few survivors, few alleles  in gene pool
      • genetic diversity restricted as they re-establish


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