Theory of Natural Selection Charles Darwin ( )

HMS Beagle

The 5-Year Journey

Galapagos Islands

Darwin’s Finches

Galapagos Island Fauna Galapagos Tortoise Marine Iguana

Galapagos Island Fauna Blue-footed Booby Galapagos Sea Lion

Theory of Natural Selection Consists of 5 main ideas: 1. Variation that is inheritable. 2. Overproduction 3. Struggle for existence 4. Survival of the fittest 5. Origin of new species by inheritance of successful variations

1. Variation Individuals within a species are not identical; they have variations. These variations may affect the individual’s ability to get food, escape predators, find a mate, etc. These variations can be passed on to offspring.

2. Overproduction Most species produce far more offspring than are needed to maintain the population.

3. Struggle for Existence Living space and food is limited and so individuals within a species must compete with each other in order to live long enough to reproduce.

4. Survival of the Fittest The individuals with traits that give them an advantage are better able to compete, survive, and reproduce, thus passing their “successful” genes onto their offspring. Nature “selects” the creatures that are best adapted to their environment.

5. Origin of New Species Over many generations, favorable adaptations gradually accumulate in the species and unfavorable ones disappear. Eventually the changes become so great that the end result is a new species.