Variation & Evolution

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  • Variation & Evolution
    • Over-production
      • More offspring are produced than survive
        • Many die without reproducing
          • Why?
            • Competition
              • Interspecific
                • Competition between two different species
                • Intraspecific
                  • Competition within the same species
              • For different resources (food, water, shelter, mates, territory etc.)
            • Natural Selection
              • Depends of 'survival of the fittest'
              • Selection pressures increase the chance
    • Selection Pressures
      • The environmental force altering the frequency of alleles in a population
        • The factor which has a direct effect on the numbers of individuals in a population of organism
      • Examples
        • Lack of food
        • Lack of water
        • Overcrowding
        • Increase in predation
        • Increase in disease
      • A change in environmental factors would have an effect on the frequency of alleles in a population
        • A change in environmental factors can either make a once un-advantageous allele advantageous and therefore its frequency within a species increases, or visa versa
    • Populations
      • A population is a group of the organisms of the same species living in the same habitat at the same time
        • A population can also be described as a group of organisms that can interbreed, occupying the same habitat
      • Gene pool
        • The total number of available alleles in a population in a specific habitat
      • Allele Frequency
        • Relative proportion of alleles (in a population)


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