Genetic diversity and adaptations

Genetic diversity is the total number of different alleles in a population or species.
1. It can increased by mutations.
  1. This is the random change in DNA's genome.
    1. This leads to a variety of alleles, giving the organisms different phenotypes.
2. It can also be increased by the introduction of new species into a population e.g. by migration.
  1. This will increase the number of different alleles and may influence interbreeding.
    1. This further increases the combination of alleles.
3. It can be decreased by a genetic bottleneck, reducing the gene pool.
  1. A genetic bottleneck is an event that wipes out a large number of organisms.
    1. A gene pool is the complete set of alleles in a population.
The founder effect
1. This is when a small part of a population becomes separated and isolated...
  1. ... Due to a genetic bottleneck.
2. An isolated population breed to increase population.
  1. The genetic diversity is small in this population because there are fewer combinations of alleles.
3. For example, an Amish population is a small group...
  1. ... and due to their small allele variation, they have a low genetic diversty.
    1. They also seemingly have similar genetic disorders.
Types of adaptations
1. Behavioural adaptations
  1. This is when it acts in a certain way to adapt to its environment.
    1. For example, possums act dead whenever they are being threatened, to avoid becoming prey.
2. Physiological adaptations
  1. This is when reactions alter in an organism's body, to make it adapt.
    1. For example, bears hibernate during winter, reducing their metabolic rate, so that the lose less energy.
3. Anatomical adaptations
  1. This is an organism's structural feature and how they look, to increase chance of survival
    1. For example, fish have a very streamlined body with tiny fins which help them swim faster, away from predators.
Types of selection
1. Stabilizing selection
  1. This is when organisms have characteristics in the middle of the range are more likely to survive
    1. E.g. a baby's weight needs to be about average so that it can survive.
2. Directional selection
  1. This is when an organism possesses single characteristic of an extreme type to help it survive.
    1. E.g. Bacteria which have become resistant to antibiotics.
3. Disruptive selection
  1. This is when an organism has characteristics of extreme types, which help it too survive
    1. E.g. Birds with large beaks can eat large seeds and birds with small beaks can eat small seeds.
      1. Birds with medium-sized beaks cannot eat small nor big...
        ... So they are doomed!

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Genetic diversity and adaptations

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