theory of natural selection charles darwin (1809-1882)
TRANSCRIPT
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
Blue-footed BoobyGalapagos 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.