1. Darwin’s Theory of Evolution
Chapter 15
Darwin’s Theory of Evolution

2. Question of the day What was the name of Darwin’s Boat? H.M.S. Beagle
Where did it go?
All over the world and back.

3. Ch. 15 Essential Questions
Why did Darwin explore the world?
Who shaped Darwin’s thinking?
What is Artificial & Natural Selection?
What is Evolution?

4. 15-1 Evolution What is Evolution? Change over time
Darwin - Modern organisms descended from ancient ones
He found enough evidence to make a theory

5. Darwin’s Travels Originally voyage was to survey Brasil and S.A.
Not intended for scientific study
Darwin was along for the ride
Visited places like:
Galapagos Islands
Falkland Islands
Tahiti

6. Darwin’s Observations
Patterns of Diversity
Organisms were different between islands
They were well adapted to environment
Organisms & Fossils
Found preserved remains that resembled modern species
Specialization
Organisms developed special traits or habits to survive in an area

8. Darwin’s Influences Hutton & Lyell Geology
Evolution of Earth’s environment
By natural events
Time, disasters, weathering, etc.

9. Darwin Thanks Lamark Darwin “borrows” theories from naturalist
Organisms evolve to be more complex & perfect
Use or disuse of limbs, behaviors
Inheiritance of acquired traits - longer legs, brighter feathers
(Example: fiddler crabs, giraffes)

10. Darwin’s Friend Malthus
Thomas Malthus - Economist
Population Growth
Resources are finite
Not enough for everyone
Life History Theory
Or difference in life spans (clams vs. humans)

11. Question of the Day
How does Darwin determine how ancestors are related between 2 species?
He looks at homologous structures, early development of embryos

12. 15-3 Darwin’s Case The Origin of Species. Book by Darwin
Talked about all his findings
Evolution has taken place for millions yrs
Will continue in the future

13. Natural Variation Darwin said species are not perfect & unchanging
Called NATURAL VARIATION (differences among individuals)
Example - aquilegia, human skin color, etc.

14. Artificial Selection Selective Breeding
Choosing the individuals unnaturally to yield best results or variation
Example - Cross Breeding of Dogs

15. Natural Selection Evolution
Darwin’s Theory of Evolution
Struggle for Existence - makes individuals of species compete for life (food, living space, mates
Survival of the Fittest - ability for individual to adapt & thrive in its environment

16. More Natural Selection
Survival of the Fittest takes many forms:
Not just biggest, fastest or strongest
Can be BEHAVIORS:
Smarter (Bigger Brain)
Teamwork (working or living in families)

17. More Natural Selection
Descent with Modification - species adapt to a NICHE different from ancestors
Niche - The function an organism within a community or particular area within a habitat occupied by an organism.
All Big Cats:
Descended from common ancestor
Made own niche

18. Evidence of Evolution How did Darwin know things were evolving?
The Fossil Record - distribution of ancient life remains
Geographic Distribution of Species - where in the world a species developed
Homologous Body Structures - similar body parts of ancestors or similar species
Early Development Characteristics - embryos & fertilized growth

19. Darwin’s Theory Summarized
Individuals in nature are different (Natural Variation)
Organisms in nature produce more offspring than can survive (Struggle for existence)
Organisms compete for limited resources (Survival of Fittest)
Individuals best suited for environment will be most successful (natural selection)
Species evolve over time & from common ancestors (Evolution, Common Descent & Descent w/ Modification)

20. Final Thoughts on Evolution
Where is the future of evolution headed?
Was Darwin right?
Could there be Devolution?
I say no because of all the scientific evidence
But You need to make up your mind