Genetic Diversity.

Biology AQA AS level unit 2, genetic diversity.

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Genetic Diversity.

  • Proteins make organisms different and determine variety of proteins.
  • All members of same species have same genes.
  • Alleles decide what genes code for, they make species and individuals different.
  • More alleles = greater diversity = more likely to adapt to change.

Selective Breeding (artifical selection):

  • Identify individuals with desired characteristics and use them as parents.
  • Unwanted alleles bred out, leading to reduction in genetic diversity and high-yielding breeds.
  • Reliable and cheap but interfering with nature.
  • When is it disabling to the animal and is just inconvenience acceptable?
  • Alleles may be of benefit in the future.
  • In Cattle:
  • AI increases pace of change.
  • Bred for milk (high production & rapid delivery) and meat (high muscle:bone ratio).
  • Mastitis (udder inflammation), lameness and infertility.
  • Killed and taken from their mother very early.
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The Founder Effect and Genetic Bottlenecks.

Founder Effect:

  • Few individuals from population colonise a new region.
  • Carry small fraction of alleles so are not representative of larger population.
  • Population develops and shows less diversity.
  • Genetically distinct populations.
  • May develop to separate species as can't adapt as well.

Genetic Bottlenecks:

  • Population has large drop in numbers.
  • Few survivors have smaller variety of alleles i.e. less genetic diversity.
  • Diversity stays restricted, few alleles therefore less likely to adapt.
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