Evolution

Evolution

1. Theories

   • Darwin's
     • Based on Natural Selection
     • Individuals compete for resources
       • Those with characteristics best suited survive
         • These individuals reproduce to produce more well-suited individuals
       • Random mutations cause variation in the species
         • This idea was found after Darwin's time
           • It was the evidence he needed
     • People objected at first
       • Theory goes against story of creation
       • Not enough evidence
       • No evidence of inheritance or variation
   • Lamarck's
     • If characteristic used a lot, that would improve over generations
     • If characteristic not used a lot, eventually disappear
     • Usually dismissed today
       • Species would become more complex
         • There are still simple organisms around today
   • Darwin's is most trusted today

2. Example

   • The Peppered Moth
     • Random mutation caused variation - some dark, some light
       • Tree surfaces are dark due to pollution
         • Dark moth less likely to be seen and eaten
           • Dark moths survive and breed
             • Dark characteristics repeated over generations

3. Classification

   • Organisation of living things according to their similarities
   • E.g. Animal and Plant Kingdoms
     • Smallest - species

4. Rapid Mutation of TB

   • 1. TB infects someone. The variation in the TB due to random gene mutations means that some bacteria are resistant to antibiotics
   • 2. After a course of antibiotics, all bacteria are killed except the resistant ones. This is through survival of the fittest and is Natural Selection
   • 3. These reproduce, passing on the resistant gene, keeping the patient ill
   • 4. So, a new drug has to be found that they are not resistant to.