Chapter 15

• Fossil records can show evolution happening over millions and millions of years
• Antibiotic resistant bacteria show evolution can also happen very quickly over a few years due to random mutations
• Species


  Something that can produce fertile offspring
• Ligers are an example of a crossbred species and they are not fertile themselves
• Mendel


  Scientist who discovered that genes are the reason things get passed on, using pea plants
• Mendel's pea plant experiments

  1. Bred green peas with yellow peas

  2. Found offspring were all green

  3. Bred green offspring together

  4. Found combinations that produced yellow peas
• Lamarck's theory of evolution

  Giraffes stretch to reach tall branches, pass on longer necks to offspring
• Lamarck's theory of evolution is now commonly accepted as wrong, replaced by natural selection
• Charles Darwin's theory of natural selection

  • Random mutation causes advantageous gene
  • Gene gets passed on through generations
• Darwin noticed different species of finches on the Galapagos islands had different beak sizes and shapes related to the food they ate
• Speciation


  Animals develop into a new species, often due to isolation from other species
• Experiments have been done to prove Wallace's theory of speciation, creating two new bee species from one by feeding them different foods