Natural Selection & Evolution

Natural Selection & Evolution

Key Concepts

  • Evolution: Change in phenotype frequency in a population over generations.
  • Natural Selection: Individuals with favorable traits survive and reproduce more, passing on these traits.
  • Antibiotic Resistance: Bacteria can develop resistance to antibiotics due to mutations and natural selection.

Charles Darwin

  • Observed evolution and developed the theory of natural selection.
  • Traveled on HMS Beagle (1831-1836).
  • Published "On the Origin of Species" in 1859.
  • Coined "survival of the fittest."

Darwin’s Theory

  • Individuals within a species show variation due to genes.
  • Those with advantageous traits are more likely to survive and reproduce.
  • These traits are passed to offspring.
  • Natural selection leads to "survival of the fittest."

Natural Selection Steps

  1. Mutations cause variation.
  2. Advantageous mutations increase survival.
  3. These mutations are passed to offspring.
  4. Mutation frequency increases over generations.

Antibiotics

  • Chemicals that kill or inhibit bacteria.

Antibiotic Resistance

  • Bacteria develop resistance through mutation.
  • Resistant bacteria survive and reproduce, spreading the resistance allele.
  • MRSA is an example of antibiotic-resistant bacteria.

MRSA

  • Resistant to many antibiotics.
  • Spreads in hospitals.

The Problem of Antibiotic Resistance

  • Limited antibiotics available.
  • Bacteria reproduce rapidly.
  • Antibiotic overuse contributes to resistance.

Solutions to Antibiotic Resistance

  • Avoid unnecessary antibiotic use.
  • Complete prescribed antibiotic courses.