Genetic biodiversity

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  • genetic biodiversity
    • factors affecting genetic biodiversity
      • decrease genetic biodiversity by decreasing no. of possible alleles
        • GENETIC BOTTLENECK few individuals survive event/change (disease, enviro change, habitat destruction)
          • reduces gene pool as only alleles of surviving members available to be passed on to offspring
        • SELCETIVE BREEDING adavntageous characteristics selected to breed e.g. food crops + pedigrees
        • CAPTIVE BREEDING PROGRAMMES zoos + conservation centres only small no. of individuals available for breeding
          • often wild pop. endangered/extinct
        • RARE BREEDS selective breeding used to produce domestic breed
          • no.'s fall when characteristics become unfashionable, leaving small no. for breeding
        • ARTIFICIAL CLONING asexual reproduction e.g. cuttings to clone farmed plants
        • NATURAL SELECTION species evolve to primarily contain alleles coding for advantageous characteristics
          • over time alleles coding for less advantageous characteristics will be lost/ only remain in few individuals
        • GENETIC DRIFT existence of an allele disappears from pop. due to random nature of alleles passed from parents
      • increase genetic biodiversity by increasing no. of possible alleles
    • The variety of genes that make up a species (aka gene pool)
      • All members of species share same genes, but different alleles create genetic biodiversity within species or population of the species
    • increased genetic biodiversity = able to adapt to changes in environment, so less likely to become extinct
      • some organisms that carry advantageous allele, enabling survival e.g. resistance to disease
    • measuring genetic biodiversity
      • proportion of polymorphic gene loci = no. polymorphic gene loci / total no. loci
        • greater proportion of polymorphic gene loci = greater genetic biodiversity
      • polymorphic genes = 2 or more alleles
        • e.g. immunoglobulin determines human blood type has 3 alleles
  • FOUNDER EFFECT small no. individuals create new colony geographically isolated from original
    • small gene pool for new pop.
    • decrease genetic biodiversity by decreasing no. of possible alleles
      • GENETIC BOTTLENECK few individuals survive event/change (disease, enviro change, habitat destruction)
        • reduces gene pool as only alleles of surviving members available to be passed on to offspring
      • SELCETIVE BREEDING adavntageous characteristics selected to breed e.g. food crops + pedigrees
      • CAPTIVE BREEDING PROGRAMMES zoos + conservation centres only small no. of individuals available for breeding
        • often wild pop. endangered/extinct
      • RARE BREEDS selective breeding used to produce domestic breed
        • no.'s fall when characteristics become unfashionable, leaving small no. for breeding
      • ARTIFICIAL CLONING asexual reproduction e.g. cuttings to clone farmed plants
      • NATURAL SELECTION species evolve to primarily contain alleles coding for advantageous characteristics
        • over time alleles coding for less advantageous characteristics will be lost/ only remain in few individuals
      • GENETIC DRIFT existence of an allele disappears from pop. due to random nature of alleles passed from parents

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