Evidence for Evolution - GCSE Biology Overview

Introduction to Evolution by Natural Selection

• Darwin and Wallace proposed the theory of evolution by natural selection.
• The theory suggests that species evolve over time through a natural process where the best-adapted individuals survive longer and reproduce more.

Key Evidence for Evolution

Antibiotic Resistance in Bacteria

• Bacteria can evolve quickly due to their fast reproduction rate.
• Mutations in Bacteria:
  • Mutations in bacteria produce new strains.
  • Some mutations lead to resistance against antibiotics, such as penicillin.
  • Resistant bacteria survive and reproduce, while non-resistant strains die out, showcasing natural selection.

Development of Antibiotic Resistance

• Steps in Development:

  • Random genetic mutations occur in bacteria.
  • Some mutations confer antibiotic resistance.
  • Non-resistant bacteria die or cannot reproduce in the presence of antibiotics.
  • Resistant bacteria thrive and reproduce with less competition.

• MRSA Example:

  • Methicillin-resistant Staphylococcus aureus (MRSA) is dangerous due to resistance to most antibiotics.
  • Increase in resistant strains partly due to the misuse of antibiotics.
  • Measures to reduce resistance:
    • Avoid inappropriate antibiotic prescriptions.
    • Complete full courses of antibiotics.
    • Restrict antibiotic use in agriculture.

Historical Context

• Discovery and Use of Antibiotics:

  • Penicillin was the first mass-produced antibiotic in the 1940s.
  • Many new antibiotics were discovered in the 1950s and 1960s.
  • Discovery rates have slowed; recent concerns over increasing resistance demand new antibiotics.

• Challenges:

  • Developing new antibiotics is costly and time-intensive.
  • Increasing resistance may lead to higher mortality from simple infections post-surgery.

Conclusion

• The evolution of antibiotic resistance in bacteria provides contemporary evidence for the theory of natural selection and evolution.
• Addressing antibiotic resistance requires careful management of antibiotic use in medicine and agriculture.

Additional Resources

• Darwin and Wallace
• Evidence for Evolution: Rats
• Evidence for Evolution: Extinction
• The Human Genome Project

This summary provides an overview of the evidence supporting evolution, focusing on antibiotic resistance as a contemporary example of natural selection.