Evidence for evolution: Inheritance, variation and evolution: Biology: GCSE (9:1)

• Fossils

  The remains of organisms from millions of years ago that are found in rocks, peat, ice or amber

  
• Fossils may be formed

  From parts of organisms that have not decayed, when parts of organisms are replaced by minerals, as trace fossils

  
• Decay

  When organisms die they typically decay due to the action of microbes such as bacteria, however decay may not occur if conditions for decay are absent

  
• Trace fossils


  Footprints, burrows, shell impressions, rootlet traces that are preserved as fossils

  
• Issues with the fossil record

  Not all organisms will fossilise and many early forms of life were soft-bodied, so very few traces of these organisms have been left behind

  
• Difficulty determining the origins of life

  Geological activity has destroyed most traces of early life forms, making it difficult for scientists to be certain how life began on Earth

  
• Interpreting the fossil record


  We can learn from fossils how much or how little organisms have changed as life developed on Earth
• Fossil evidence


  Fossils have been found that are very similar to existing organisms, suggesting modern organisms may have evolved from or share a common ancestor with these ancient organisms

  
• Evolutionary trees


  A branched diagram that represents the relationship between many living and extinct organisms based on physical and genetic characteristics

  
• Antibiotic resistance in bacteria

  Resistant bacteria display evidence for evolution, where some bacteria have undergone mutations making them better adapted to surviving in antibiotic conditions

  
• Antibiotic


  A medication used to kill bacteria, some bacterial strains have mutated and become resistant making it difficult to treat an infection

  
• Artificial selection


  Natural selection can be sped up in organisms via selective breeding, as demonstrated by Darwin who bred many fancy pigeons with very different characteristics

  
• Gene evidence


  An increased understanding of genetics provides support for evolution as it has been shown that characteristics are passed on to offspring in genes

  
• Natural selection


  A process where individuals in a population display variations that put them at a biological advantage, increasing the chances that these individuals will successfully reproduce and pass on their adaptive traits

  
• Evolution

  A change in the inherited characteristics of a population over time through the process of natural selection, can result in the formation of new species

  
• The theory of evolution by natural selection


  A now widely accepted theory that has been supported by evidence, the theory suggests organisms can change over time due to natural selection