2. Chapter 15 Part 1
Pg. 91
Evolution Introduction

3. Definitions to Know
Scientific Theory = a well-supported, testable explanation of phenomena that have occurred in the natural world.
Evolution = change over time, the process by which modern organisms descended from ancient organisms
Is Evolution Fact or Fiction?
Scientists believe it’s Fact.
Proof?
Fossils
Speciation
Geological evidence
DNA evidence

4. Charles Darwin ( )
British naturalist famous for his theories of evolution and natural selection.
Like several scientists before him, Darwin believed all the life on earth evolved (developed gradually) over millions of years from a few common ancestors.
In 1831, Darwin took a trip around the world on the ship, the M.S. Beagle, where he collected evidence that led him to propose his famous Theory of Evolution.
Charles Darwin

5. Fossils Fossils = preserved remains of ancient organisms
Darwin didn’t just observe and collect living animals, he also collected fossils.
Fossils = preserved remains of ancient organisms
This led to questions like….
“Where did all these organisms go?” “Why aren’t they still here?” “Why do they resemble organisms we have living today?”
Armadillo= alive
Glyptodon = dead

6. The Galapagos Islands
The most important, influential stop on Darwin’s trip was the Galapagos Islands
1000 km west of S. America, a cluster of islands isolated by miles of sea
The islands had different climates, and therefore, had different varieties of animals and plants
Animals Darwin studied:
Box 7
3. Finches
Giant Tortoises
2. Iguanas

7. Galapagos Turtles
Each turtle lives on a certain island, and their shells are different, island-dependent!
Pinta
Tower
Marchena
Pinta Island Intermediate shell
Hood Island
Saddle-backed shell
Fernandina
James
Santa Cruz
Isabela
Santa Fe
Floreana
Hood
The shape of each turtle’s shell is different and the different shapes depend on the turtle’s habitat.
Isabela Island
Dome-shaped shell

8. Darwin’s Finches
Darwin also collected finches, birds, matching their beak and body shapes with different islands- just like the tortoises.
Adaptive Radiation – the evolutionary process through which a single lineage gives rise to species occupying diverse environmental niches.
Tree Finch
Ground finch
In other words, if you get separated from your own species, you evolve or change in response to your environment.

9. Darwin’s Finches
Leaves
Seeds and Fruit
Seeds
Insects
Grubs
Tool using

10. What took him so long? 25 years later….
In 1858, Alfred Wallace sent Darwin an essay with the same ideas about evolution!
They presented their work together at a conference, but….
This pushed Darwin to publish his work, before Wallace
The Origin of the Species
Proposed a mechanism for evolution, called Natural Selection
Presented evidence that evolution has been happening for millions of years