Transcript Survival of the Fittest

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.