Evidence for evolution

• Fossils:

  • remains of organisms from millions of years ago found in rocks
• fossil formation:

  • when parts of organisms have NOT decayed because conditions needed for decay are absent (eg temp too cold)
  • When fossil decays and parts of the organism are slowly replaced by minerals during the decay process
  • preserved traces of organisms (eg-footprints)
• how do fossils show evolution?

  • show lots of species that have now become extinct
  • can show changes changes in species over time (evolution) from millions of years
• Bacteria -

  • reproduce/evolve rapidly
  • Some evolved and became antibiotic-resistant
• Antibiotic resistant bacteria

  • MRSA
• antibiotic resistance process-

  • A mutation occurs and it becomes resistant
  • when an antibiotic is used the weaker bacteria is killed, leaving the resistant one
  • it survives and reproduces
  • over time the population of this resistant strain rises and spreads and there is no effective treatment
• How to reduce development of antibiotic resistance:

  • don't prescribe antibiotics inappropriately
  • patients complete course of antibiotics so ALL bacteria is killed and none can survive to mutate to make resistant strains
  • restrict antibiotics in farming