1. The Evolution of an IDEA!!!
Objectives:
Describe the contributions of early scientists to modern theories of evolution
Explain the fundamental theory of evolution
Discuss some questions and ideas that shaped Darwin’s thinking

2. In your own words, describe what YOU think the theory of evolution means…

3. Charles Darwin

4. Darwin’s Theory of Evolution
Evolution, or change over time, is the process by which modern organisms have descended from ancient organisms.
A scientific theory is a well-supported testable explanation of phenomena that have occurred in the natural world.

5. How did Darwin came up with his theory?
…well first we have to have a look at those who came before Darwin.
These people changed the way we look at the world around us.
Darwin’s theory was greatly influenced by the following people.

6. Ideas that shaped Darwin’s Thinking
James Hutton:
Theory of Geological change
Forces are changing the shape of the Earth’s surface
These changes are very slow
The Earth is much older than the thousands of years we once thought!

7. George Cuvier: Fossil Studies
(1769 – 1832)
He noted that fossils can be simple or complex
Fossils of simpler organisms seem to be found in deeper layers of rock and soil
Fossils of more complex organisms seemed to be found at relatively shallower depths
The shallower the depth a fossil is found in, the more closely it is likely to resemble a living species
He also noted that some rock layers contained fossils of organisms that didn’t occur in any other layer
Theory of Catastrophism:
Catastrophes like floods caused
extinctions of species (which could be
found in the fossil layers) and these
species were replaced by new species.

8. Charles Lyell: Theory of Uniformitarianism
Published ‘Principles of Geology’
Earth has been changed in the past and is still changing now
Geological change is very slow
Hypothesized that mountains were and are still being formed by gradual processes and areas of land are being slowly worn/eroded away
Darwin thought if the Earth changed over time, what about life on the Earth?

9. Lamarck

11. Lamarck's Principles
Use and Disuse: Structures an animal used became bigger and stronger, while structures that were not used became smaller and weaker.
Inheritance of Acquired Characteristics: An animal could pass on the traits it had acquired throughout its life to its offspring

13. What did we get from Lamarck??
Lamarck hypothesized that…
All species evolve over time.
A species evolves in response to its environment so that it is better able to survive (adaptation)
Changes get passed on from generation to generation
Lamarck’s theory, while flawed got the ball rolling for modern day thinking about how and why species change.

14. Population Growth – Why do species need to change???
Thomas Malthus-19th century English economist
If populations grew indefinitely(more Babies born than die)
Insufficient living space
Food runs out
Darwin applied this theory to animals

15. On to Darwin…The Voyage of the Beagle

16. Voyage of Beagle Dates: February 12th, 1831 Captain: Charles Darwin
Ship: H.M.S. Beagle
Destination: Voyage around the world.
Findings: Evidence to propose a revolutionary hypothesis/theory about how life changes over time

18. Patterns of Diversity (Questions)
Darwin visited Argentina and Australia which had similar grassland ecosystems.
Those grasslands were inhabited by very different animals.
Neither Argentina nor Australia was home to the sorts of animals that lived in European grasslands.
Why??? Wouldn’t similar environments be home to similar species??

19. Patterns of Diversity Darwin posed challenging questions.
Why were there no rabbits in Australia, despite the presence of habitats that seemed perfect for them?
Why were there no kangaroos in England?

20. Living Organisms and Fossils
Darwin collected the preserved remains of ancient organisms, called fossils.
Some of those fossils resembled organisms that were still alive today.

21. Living Organisms and Fossils
Others looked completely unlike any creature he had ever seen.
As Darwin studied fossils, new questions arose.
Why had so many of these species disappeared?
How were they related to living species?

24. Publication of Origin of Species
Russel Wallace wrote an essay summarizing evolutionary change from his field work in Malaysia
Gave Darwin the drive to publish his findings

25. Read through your hand out and answer questions 1-3.
Your Task
Read through your hand out and answer questions 1-3.
For HOMEWORK tonight!!
Read Adaptive Radiation: Darwin’s Finches to learn more about what Darwin discovered on his voyage.
Answer the questions
I am away tomorrow. There will be a QUIZ on Thursday based today’s lesson and your work tomorrow!

26. Mechanisms for Evolution
Natural variation--differences among individuals of a species
Artificial selection- nature provides the variation among different organisms, and humans select those variations they find useful.

27. Artificial Selection

28. Other Mechanisms that Drive Evolution
Sexual Selection: the process by which a trait that enables an organism to acquire more mates becomes more common.
Males compete for females (combat)
Females chose males (desirable traits)

29. Genetic Variation Evolution requires genetic variation.
New genes being introduced results in diversity of offspring.
Mutations: Source of genetic variation
Light and Dark Moths
Dark Moths increased in frequency during industrial revolution because of dark soot in air
Dark Moths could hide from birds

30. Descent
Descent with Modification-Each living organism has descended, with changes from other species over time
Common Descent- were derived from common ancestors

31. Evidence of Evolution The Fossil Record
Comparative anatomy/Homologous Body Structures

32. Similarities in Early Development
Biochemistry and DNA
Vestigial organs
Observation of Direct Species Change

33. Evidence for Evolution
The Fossil Record-Layer show change
Shows numbers extinct animals
Shows similarities between extinct animals and animals that are alive today
The earth’s layers show a time scale of species and when they appeared on earth (and when they died out)

36. Transitional fossils are fossils that show intermediary links between groups of organisms
They can provide a link between the past and present

37. Biochemistry and DNA
When comparing the DNA of one species to another, more similarities are found in species that are more closely related.

38. Direct observation of species change
Bacteria become resistant to antibiotics
Wolves were bred over many generations to become dogs (artificial selection) • and then bred further to create a variety of breeds

39. Your Task
With your partner, review the 4 mechanisms for evolution that you learned about today.
Explain each mechanism for evolution in your own words. How do you think each of these mechanisms drove evolution?