1. Chapter 15 Darwin’s Theory of Evolution
15-1The puzzle of Life’s Diversity
15-2Ideas That Shaped Darwin’s Thinking
15-3Darwin Presents His Case

2. 15-1The Puzzle of Life’s Diversity
Objectives
What was Charles Darwin’s contribution to science?
What pattern did Darwin observe among organisms of the Galapagos Islands?

3. Introduction Biological diversity: variety of living things
Evolution: (change over time) the process by which modern organisms have descended from ancient organisms
Scientific theory: a well-supported testable explanation of phenomena that have occurred in the natural world

4. Voyage of the Beagle
Charles Darwin was the naturalist on board the H.M.S. Beagle in 1831
Made many observations and collected evidence that led him to propose a revolutionary hypothesis about the way life changes over time
Has become the theory of evolution

5. Darwin’s Observations
Darwin observed and recorded many different species of organisms each time the Beagle docked

6. Patterns of Diversity
Darwin noticed many plants and animals were equipped to survive in certain environments
He questioned why organisms lived in one area but not another

7. Living Organisms and Fossils
Fossils: preserved remains of ancient organisms
Some fossils resembled organisms that were still alive

8. The Galapagos Islands Close together Different climates Lowest islands
Hot, dry, little vegetation
Higher islands
More rainfall, variety of plants and animals, lots of vegetation

9. The Galapagos Islands Cont’d
Organisms varied from island to island
Iguanas
Land tortoises

10. Blue Ticket Question
How did the fossils Darwin observed compare with the living organisms he studied?

11. Blue Ticket Answer
Some of the fossils resembled organisms that were still alive

12. The Galapagos Islands Cont’d
Collected several types of small, ordinary-looking brown birds hopping around
Different shaped beaks

13. The Journey Home
Darwin observed that the characteristics of many animals and plants varied noticeable among the different islands of the Galapagos.
He wondered if these organisms had a common ancestor and evolved differently after being isolated from each other

14. 15-1 Exit Ticket