Robert Fitzroy Invited to travel around the world (22 years old!) makes many observations of nature main mission of the Beagle was to chart South American coastline

Charles Lyell Book: Principles of Geography (1833) Argued that land forms changed constantly. Ex. marine snail shell fossils found on high mountains Darwin thought if earth changed over time, what about life?

Presented in 1801 Use and Disuse: Individuals lose characteristics they do not require (or use) and develop characteristics that are useful This leads to Darwin’s idea of natural selection

LaMarck evolution by acquired traits creatures developed traits during their lifetime give those traits to their offspring Ex. To reach higher leaves giraffes stretch their necks & give the acquired longer neck to offspring LaMarck evolution by acquired traits creatures developed traits during their lifetime give those traits to their offspring Ex. To reach higher leaves giraffes stretch their necks & give the acquired longer neck to offspring

Take him to the Galapagos Islands, 500 mi. off the coast of Ecuador, South America, On the Galapagos Islands, Darwin observed species that lived no where else in the world. These observations led Darwin to write a book about his own theory of evolution.

Finch?Sparrow? Woodpecker? Warbler? Finch?Sparrow? Woodpecker? Warbler? Many different birds lived on the Galapagos Islands. He thought he found very different kinds…

Darwin was amazed to find out: All 14 species of birds were finches… Finch?Sparrow? Woodpecker? Warbler? Finch? Sparrow? Woodpecker? Warbler? Large ground finch Small ground finch Warbler finchTree finch But there is only one species of finch on the mainland! Darwin asked: If the Galapagos finches came from the mainland, why are they so different now?

Finch?Sparrow? Woodpecker? Warbler? Large ground finch Small ground finch Warbler finchTree finch Big seed eaterSmall seed eater Insect eaterLeaf & bud eater Darwin said: Ahaaaa! A flock of South American finches were stranded on the Galapagos… Darwin found: The differences between species of finches were associated with the different food they ate. Different beaks are inherited variations Beak adaptations help birds compete for food These birds survive & reproduce Pass on the genes for those more fit beaks Over time nature selected different species with different beaks

Warbler finch Woodpecker finch Small insectivorous tree finch Large insectivorous tree finch Vegetarian tree finch Cactus finch Sharp-beaked finch Small ground finch Medium ground finch Large ground finch Insect eaters Bud eater Seed eaters Cactus eater Warbler finch Tree finches Ground finches variation natural selection for best survival & reproduction

Galapagos video clip

Darwin giraffes that already have long necks survive better leave more offspring who inherit their long necks variation selection & survival reproduction & inheritance of more fit traits

Published by Darwin in 1859 Proposes mechanism for natural selection Presents evidence that evolution has been occurring for millions of years Evolution, or change over time, is the process by which modern organisms have descended from ancient organisms Evolution Species were NOT created in their current form Darwin video clip