Natural selection

• What is a selection pressure?


  Anything that affects an organism's chance of survival and reproduction
• Why do individuals of the same species vary?


  they have difference alleles
• What creates a struggle for survival?

  • predators
  • disease
  • competition
  • 
    
  • SELECTION PRESSURES
• Why are some individuals better adapted to the selection pressures than others?


  Because individuals vary
• There are different levels of what?


  Survival and reproductive success in a population