CHAPTER 16: DARWIN’S THEORY OF EVOLUTIONSection 16-1: Darwin’s Voyage of Discovery

DARWIN’S EPIC JOURNEY

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.

OBSERVATIONS ABOARD THE BEAGLE

Darwin traveled on the HMS Beagle as naturalist for 5 years, collecting specimens of plants and animals from around the world

OBSERVATIONS ABOARD THE BEAGLE

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

SPECIES VARY GLOBALLY

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

SPECIES VARY LOCALLY

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

SPECIES VARY OVER TIME

Collected fossils – the preserved remains/traces of ancient organisms

Noticed that some fossils of extinct animals were similar to living species

PUTTING THE PIECES TOGETHER

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