Chapter 16: Darwin’s Theory of Evolution

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Transcript Chapter 16: Darwin’s Theory of Evolution

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Section 16-1: Darwin’s Voyage of Discovery

D ARWIN ’ S E PIC J OURNEY   Charles Darwin – born February 12, 1809 in England Scientific view of natural world dramatically changing   Geologists – Earth ancient, changed over time Biologists – life changed   Evolution = change over time

Darwin developed a scientific theory of biological evolution that explains how modern organisms evolved over long periods of time through descent from common ancestors.

O BSERVATIONS A BOARD THE B EAGLE  Darwin traveled on the HMS Beagle as naturalist for 5 years, collecting specimens of plants and animals from around the world

O BSERVATIONS A BOARD THE B EAGLE  Amazed by the variety/number of living things   Filled notebooks with observations of characteristics/habitats Noticed three patterns of biological diversity:    Species vary globally Species vary locally Species vary over time

S PECIES V ARY G LOBALLY  Different, yet ecologically similar, animal species inhabited separated, but ecologically similar, habitats around the globe  Rheas of South America look/act like ostriches of Africa, emus of Australia  Live in grasslands – not ALL species the same

S PECIES V ARY L OCALLY     Different, yet related, animal species often occupied different habitats within a local area Galapagos Islands – very close, but very different conditions Tortoises vary in a predictable way BIRDS

S PECIES V ARY O VER T IME   Collected fossils – the preserved remains/traces of ancient organisms Noticed that some fossils of extinct animals were similar to living species

P UTTING THE P IECES T OGETHER     Darwin analyzed patterns he observed on the voyage home Sent plant/animal specimens to be identified Galapagos animals unique, but similar to South American species Evidence suggested species were not fixed – changed by some natural process