Genetic diversity

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  • Created by: Laura
  • Created on: 17-04-14 10:55
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  • Genetic Diversity
    • Organisms are varied. Over 1.8 million species of organisms have been identified. Every species is different.
    • The greater the number of different alleles that all members of a species possess, the greater the genetic diversity of that species
    • The greater the genetic diversity of a species, the more likely it will be to be able to adapt to some environmental change.
    • Selective Breeding
      • Selective breeding is also known as artificial selection. It involves identifying individuals with the desired characteristic and using them to parent the next generation
      • Offspring that do not exhibit the desired characteristic are killed or at least prevented from breeding
      • Alleles for unwanted characteristics are bred out of the population
      • The variety of alleles in a population is deliberately restricted to a small number of desired alleles. Reduces genetic diversity
      • Usually used to produce high yielding breeds of domesticated animals and strains of plants
    • The Founder Effect
      • The founder effect occurs when just a few individuals from a population colonies a new region
      • These few individuals will carry with them only a small fraction of the alleles of the population as a whole. These alleles may not be representative of the general population
      • The new population that develops will therefore show less genetic diversity than the population from which it came
      • The founder effect is usually seen when new volcanic islands rise out the sea. The new population in time may form a new species.
      • As the new species has fewer alleles it is less able to adapt to its environment
    • Genetic Bottlenecks
      • Populations form time to time may suffer a dramatic drop in numbers. Sometimes the reason for this drop is a chance event, such as a volcanic eruption
      • The few survivors will  possess a much smaller variety of alleles than the original population - the genetic diversity will be less
      • As these few individuals breed and become re-established, the genetic diversity of the new population will remain restricted

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