Natural selection.

Darwin formed his hypothesis of natural selection by drawing two inferences based on his observations.

  • Observation #1 : Individuals of a population exhibit variation in their traits.
  • Observation #2 : Many traits are heritable.
  • Observation #3 : Many species overproduce offspring.
  • Observation #4 : Resources are limited; many of these offspring do not survive due to competition for those resources. _________________________________________________________________

  • Inference #1 (natural selection): Individuals whose traits give them a high probability of surviving and reproducing are likely to leave more offspring than others.
  • Inference #2 (adaptation): A population will accumulate favorable traits over generations and become adapted to its environment.