Theory of Natural Selection Charles Darwin was born into a rich family - his father was a physician. At his father’s urgings, Darwin studied medicine, but gave it up. He then pursued theology to become a minister in the Church of England and gave that up as well for his real love which was nature - studying animals. Charles Darwin Alfred Wallace

HMS Beagle When he was 22 years old, Darwin applied to be the naturalist aboard a ship, HMS Beagle, that was setting out from England to go chart the coastline around South America. The expedition was to last 2 years, but ended up lasting 5. During that time, Darwin collected many specimens and made detailed observations about the species he encountered.

Galapagos Islands The most significant of Darwin’s observations were those he made on the Galapagos Islands off the coast of Ecuador. He found species here that were similar to ones on the mainland, but they were slightly different in certain characteristics.

Galapagos Island Fauna Blue-footed Booby Marine Iguana

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

Natural Selection, cont’d Overproduction Most species produce far more offspring than are needed to maintain the population. Only a few will survive long enough to reproduce.

Natural Selection, cont’d Struggle for existence Living space and food is limited and so species must compete with each other in order to live long enough to reproduce.

Natural Selection, cont’d 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.

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

Natural Selection, cont’d 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.