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Theory of Natural Selection Charles Darwin (1809-1882) HMS Beagle The 5-Year Journey Galapagos Islands Darwin’s Finches Galapagos Island Fauna Galapagos Tortoise Marine Iguana Galapagos Island Fauna Galapagos Sea Lion Blue-footed Booby 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.