1. The Evidence for Evolution
Chapter 9
Where Did We Come From?
The Evidence for Evolution

2. Chapter 9 Section 1
What is Evolution?

3. 9.1 What is Evolution? What is Evolution?
Two different ways scientists think of evolution
The Process of Evolution
The Theory of Evolution

4. 9.1 What is Evolution? The Process of Evolution
Biological evolution – change in the characteristics of a population of organisms that occurs of over the course of generations.
Evolutionary changes are inherited via genes
Other changes may take place because of environmental changes and are not necessarily evolutionary.

5. 9.1 What is Evolution? Definitions
Species = a group of individuals that:
Can regularly breed together
Can produce fertile offspring
Are distinct from other species in appearance or behavior.
Population = a group of individuals of a species that are separated by geography.

6. 9.1 What is Evolution? - The Process of Evolution
Example
Pesticide resistant lice are an example of biological evolution.
Figure 9.1

7. 9.1 What is Evolution? -The Process of Evolution
Populations evolve, NOT individuals.
In the lice example, the genetic structure of the population of lice changed.
Individuals without a gene for resistance died
But individuals with resistance survived to breed again
Over time, the population changed to mostly resistant individuals

8. 9.1 What is Evolution? -The Process of Evolution
Why do populations evolve?
Natural selection = the differential survival and reproduction of individuals in a population.
Process by which populations adapt to changing environments
Examples:
Pesticide resistance in crop-eating insects
Antibiotic resistance in infectious bacteria

9. How Natural Selection Works
1. Offspring have different traits, some of which are inheritable.
 2. Some traits are beneficial, and help the individual to survive, whereas others are harmful.
 3. Organisms produce more young than can survive.
 4. Organisms with beneficial traits have a better chance of surviving and passing on their characteristics to the next generation than those with harmful traits.
 5. Therefore, over time, beneficial traits are perpetuated in the lineage, while harmful traits disappear.

10. 9.1 What is Evolution? Two different scales of evolution
Microevolution – changes that occur within a species due to changing characteristics of a population.
Easily observed, relatively non-controversial.
Macroevolution – changes that occur, as a result of microevolution, over long periods of time and result in the origin of new species.
Controversial among non-biologists.

11. 9.1 What is Evolution? Theory of Evolution The Theory of Evolution has Two Parts
All species present on earth today:
Represent the product of millions of years of accumulated evolutionary changes.
Are descendants of a single common ancestor
Aka the theory of common descent

12. 9.1 What is Evolution?
The Theory of Common Descent
Figure 9.2

13. 9.1 What is Evolution? Why is it controversial?
Ambiguity of the word “theory”
Everyday usage: theory = best guess, or tentative explanation
Scientific usage: theory = body of accepted general principles, supported by many lines of evidence.
Examples: atomic theory, gravity, germ theory.

14. End Chapter 9 Section 1
What is Evolution?

15. the Theory of Evolution
Chapter 9 Section 2
Charles Darwin and
the Theory of Evolution

16. 9.2 Charles Darwin and the Theory of Evolution
Theory of Evolution is sometimes called “Darwinism” because Charles Darwin is largely credited with introducing the concept to mainstream science.

17. 9.2 Charles Darwin Early Views of Evolution
Charles Darwin did not “invent” the idea of evolution. Many philosophers of science had notions of organisms changing over time.
Fossils had caused people to propose animals evolved
Anaximander – Greek philosopher ( BC) who first suggested that humans evolved from fish that had moved onto land
Jean Baptiste Lamarck – published ideas about inheritance of acquired traits in 1809

18. 9.2 Charles Darwin The Voyage of the Beagle
In 1831 at age 22, Darwin set sail as ship’s naturalist aboard the HMS Beagle on a five year long trip to map S. America.
Darwin’s job was to collect and observe “anything worth to be noted for natural history.”

19. 9.2 Charles Darwin &Theory of Evolution The Voyage of the Beagle
The following had influences on Darwin during the voyage:
Darwin had a book by Lyell, Principles of Geology, which postulated earth was old and changes occurred over long periods of time.
Rainforests of Brazil
Fossils that he collected
Birds and reptiles of the Galapagos Islands

20. 9.2 Charles Darwin & the Theory of Evolution The Voyage of the Beagle
Galapagos islands tortoises vary with their environments.
Figure 9.5

21. 9.2 Charles Darwin & the Theory of Evolution Developing the Hypothesis of Common Descent
Darwin returned to England in 1836, but did not publish his ideas immediately.
Spent about 20 years refining his ideas
Learned about animal husbandry (selective breeding)
Finally published On the Origin of Species in 1858

22. the Theory of Evolution
End Chapter 9 Section 2
Charles Darwin and
the Theory of Evolution

23. Examining the Evidence
Chapter 9 Section 3
Examining the Evidence
for Evolution

24. 9.3 Examining the Evidence for Evolution
Evolution versus Creation
Intelligent Design and Creation
God created organisms during 6 days as described in Genesis
Life has not significantly changed since then
Some claim creation occurred recently, within the past 10,000 years
Science can NOT test hypothesis based upon supernatural forces
But physical aspects can be tested

25. 9.3 Examining the Evidence for Evolution
Four Proposed explanations for life on earth
Static model hypothesis (creation or intelligent design)
Transformation hypothesis

26. 9.3 Examining the Evidence for Evolution
Four Proposed explanations for life on earth
Separate Types Hypothesis
Theory of Common Origin (theory of evolution)

27. 9.3 Examining the Evidence for Evolution An Overview of Evidence for Evolution
Several lines of biological evidence point to a common ancestor:
Biological classification
Anatomical similarities between organisms
Useless traits in modern species
Shared developmental pathways
DNA similarities
Distribution of organisms on earth (biogeography)
Fossil evidence

28. 9.3 Examining the Evidence for Evolution - An Overview of Evidence for Evolution
Biological classification implies common ancestry.
Carl Linnaeus
Figure 9.8

29. 9.3 Examining the Evidence for Evolution - An Overview of Evidence for Evolution
Anatomical similarities between organisms. Mammalian forelimbs have the same set of bones. The underlying structure is similar despite the very different functions.
Bat
Sea lion
Lion
Chimpanzee
Human
Humerus
Radius and ulna
Carpals
Metacarpals
Phalanges
Figure 9.9

30. 9.3 Examining the Evidence for Evolution - An Overview of Evidence for Evolution
Vestigial & useless traits in modern species.
Tail bones in humans

31. 9.3 Examining the Evidence for Evolution - An Overview of Evidence for Evolution
Shared developmental pathways. Similarity among chordate embryos.
Figure 9.11

32. 9.3 Examining the Evidence for Evolution - An Overview of Evidence for Evolution
DNA similarities. Birds in same genus have DNA that is more similar to one another, while distantly-classified birds have DNA that is less similar.
Figure 9.12

33. 9.3 Examining the Evidence for Evolution - An Overview of Evidence for Evolution
Biogeography
Distribution of organisms on earth.
Different species of mockingbird found on Galapagos all resemble another species found on the mainland.
Figure 9.13

34. 9.3 Examining the Evidence for Evolution - An Overview of Evidence for Evolution
Fossil evidence.
Horse fossils provide a good sequence of evolutionary change within a lineage.
Figure 9.14

35. 9.3 Examining the Evidence for Evolution
PLAY
Animation—Principles of Evolution

36. Examining the Evidence
End Chapter 9 Section 3
Examining the Evidence
for Evolution

37. Are Alternatives to the Theory of Evolution Equally Valid?
Chapter 9 Section 4
Part A
Are Alternatives to the Theory of Evolution Equally Valid?

38. 9.4 Are Alternatives to the Theory of Evolution Equally Valid?
Weighing the Alternatives
Static model
Transformation
Separate types
Common descent
Rejected
Rejected
Rejected
Supported by a wide variety of evidence, including comparative anatomy, DNA sequences, and the fossil record.
Earth is far older than 10,000 years, and species have clearly changed over time.
Evidence of relationships among organisms abound.
Universality of DNA, genetic code, and cell components are evidence of a single origin of all life.
Figure 9.27

39. 9.4 Are Alternatives to the Theory of Evolution Equally Valid?
Static Model
Predicts earth is less than 10,000 years old
Radiometric dating proves earth is far older
Predicts all species arose individually and have not changed
Fossil evidence proves organisms have changed over time
Figure 9.27

40. 9.4 Are Alternatives to the Theory of Evolution Equally Valid?
Transformation Model
Predicts species arose separately and then evolved, but no new species
No reason to expect different species would share structures
Especially vestigial structures
No reason to expect similarities in DNA sequences
Predicts little evidence of relatedness
Abundant evidence of species relatedness
Figure 9.27

41. 9.4 Are Alternatives to the Theory of Evolution Equally Valid?
Separate Types Model
Predicts that different groups arose separately and then evolved new species
No reason to expect genetic code to be universal
But genetic code is universal
Method for translating genes into proteins is universal
EXP: Genes from bacteria can be put into plants, which then make bacterial proteins
Figure 9.27

42. 9.4 Are Alternatives to the Theory of Evolution Equally Valid?
Common Descent Model
Predicts that species evolved from common ancestor
Supported by:
Biological classification
Anatomical homology
Vestigial traits
Biogeography
Homology of development
Homology of DNA
Fossil Record
Figure 9.27

43. Are Alternatives to the Theory of Evolution Equally Valid?
Chapter 9 Section 4
End Part A
Are Alternatives to the Theory of Evolution Equally Valid?

44. Chapter 9 Section 4
Part B
How Did Life Begin?

45. 9.4 The Origin of Life The Origin of Life
Evolution is the study of how life changes
It doesn’t address how life first began

46. 9.4 The Origin of Life
A Hypothesis for Origin of Life from Nonliving Precursors
Simple molecules present early in earth’s history (CH4, NH3, H2O, H2) assembled into more complex molecules (such as nucleotides & amino acids)
These molecules assembled into chains that could store information (nucleic acids & proteins)
These more complex molecules became organized into self-replicating “cells”

47. 9.4 Experiment evidence does give some clues about beginnings of life
Origin of life
The Miller-Urey experiment in 1953 demonstrated that complex molecules can spontaneously form from simple chemicals.
Figure 9.29

48. 9.4 Experiment evidence does give some clues about beginnings of life
Origin of life
The Miller-Urey experiment demonstrated that complex molecules can spontaneously form from simple chemicals.
Later experiments showed that simple precursors spontaneously form polymers to form proteins, DNA and RNA when put into contact with hot sand, clay or rock
Figure 9.29

49. 9.4 Experiment evidence does give some clues about beginnings of life
In 1980 scientists showed RNA, which carries genetic info., could copy itself
Demonstrated capacity for self-replication
Phospholipids put into water spontaneously form cell like lipid bilayers
Conclusions
These experiments suggest life could have started spontaneously in earths early environment
No one has been able to create life as we know it in the lab

50. 9.4 Importance of The Theory of Evolution
Evolutionary theory informs all aspects of modern biology.
It is important because it helps scientists grapple with modern issues.
Examples:
To understand the function of human genes
To understanding species interactions
For predicting the biological consequences of climate change

51. End Chapter 9 Section 4
Part B
How Did Life Begin?

52. End Chapter 9