2. 17–1 The Fossil Record A. Fossils and Ancient Life
The fossil record provides evidence about the history of life on earth. It also shows how different groups of organisms have changed over time

3. 17–1 The Fossil Record How Fossils Form
Most fossils form in sedimentary rock. It is formed when exposure to rain, heat, wind and cold breaks down clay
As layers of sediment build up over time, dead organisms may also sink to the bottom and become buried
Conditions are right, the remains may be kept intact

4. 17–1 The Fossil Record C. Interpreting Fossil Evidence
1. Relative Dating- the age of a fossil is determined by comparing its placement with that of fossils in other layers of rock (estimate age of fossils)
2. Radioactive Dating- scientists calculate the age of a sample based on the amount of remaining radioactive isotopes it contains

5. 17–1 The Fossil Record
D. Geologic Time Scale
Eras
2. Periods

6. Comparing Relative and Absolute Dating of Fossils
Section 17-1
Compare/Contrast Table
Comparing Relative and Absolute Dating of Fossils
Can determine
Is performed by
Drawbacks
Relative Dating
Absolute Dating
Age of fossil with respect to another rock or fossil (that is, older or younger)
Age of a fossil in years
Comparing depth of a fossil’s source stratum to the position of a reference fossil or rock
Determining the relative amounts of a radioactive isotope and nonradioactive isotope in a specimen
Imprecision and limitations of age data
Difficulty of radio assay laboratory methods
Go to Section:

7. Figure 17-2 Formation of a Fossil
Section 17-1
Figure 17-2 Formation of a Fossil
Water carries small rock particles to lakes and seas.
Dead organisms are buried by layers of sediment, which forms new rock.
The preserved remains may later be discovered and studied.
Go to Section:

8. Figure 17-5 Geologic Time Scale
Section 17-1
(millions of years ago)
Era
Period
Time
(millions of years ago)
Era
Period
Time
(millions of years ago)
Era
Period
Time
Permian
Carboniferous
Devonian
Silurian
Ordovician
Cambrian
290 – 245
363–290
410–363
440–410
505–440
544–505
Quarternary
Tertiary
Cretaceous
Jurassic
Triassic
1.8–present
65–1.8
145–65
208–145
245–208
Vendian
650–544
Go to Section:

9. Figure 17-5 Geologic Time Scale
Section 17-1
(millions of years ago)
Era
Period
Time
(millions of years ago)
Era
Period
Time
(millions of years ago)
Era
Period
Time
Permian
Carboniferous
Devonian
Silurian
Ordovician
Cambrian
290 – 245
363–290
410–363
440–410
505–440
544–505
Quarternary
Tertiary
Cretaceous
Jurassic
Triassic
1.8–present
65–1.8
145–65
208–145
245–208
Vendian
650–544

10. Figure 17-5 Geologic Time Scale
Section 17-1
(millions of years ago)
Era
Period
Time
(millions of years ago)
Era
Period
Time
(millions of years ago)
Era
Period
Time
Permian
Carboniferous
Devonian
Silurian
Ordovician
Cambrian
290 – 245
363–290
410–363
440–410
505–440
544–505
Quarternary
Tertiary
Cretaceous
Jurassic
Triassic
1.8–present
65–1.8
145–65
208–145
245–208
Vendian
650–544

11. 17–2 Earth’s Early History
A. Formation of Earth
Earth’s early atmosphere probably contained hydrogen cyanide, carbon dioxide, carbon monoxide, nitrogen, hydrogen sulfide, and water

12. 17–2 Earth’s Early History
The First Organic Molecules
Organic molecules would have been able to be constructed but the oxygen in atmosphere was to reactive and would destroy any organic molecules that formed

13. 17–2 Earth’s Early History
C. How Did Life Begin?
1. Formation of Microspheres- protection that allowed for the growth of organic molecules
2. Evolution of RNA and DNA- still unanswered but scientists are searching

14. 17–2 Earth’s Early History
Free Oxygen
The rise of oxygen in the atmosphere drove some life forms to extinction, while other life forms evolved new, more efficient metabolic pathways that used oxygen for respiration

15. 17–2 Earth’s Early History
Origin of Eukaryotic Cells
The endosymbiotic theory proposes that eukaryotic cells arose from living communities formed by prokaryotic organisms

16. Figure 17-12 Endosymbiotic Theory
Chloroplast
Plants and plantlike protists
Aerobic bacteria
Ancient Prokaryotes
Nuclear envelope evolving
Photosynthetic bacteria
Mitochondrion
Primitive Photosynthetic Eukaryote
Animals, fungi, and non-plantlike protists
Ancient Anaerobic Prokaryote
Primitive Aerobic Eukaryote
Go to Section:

17. 17–2 Earth’s Early History
F. Sexual Reproduction and Multicellularity
A few hundred million years after the evolution of sexual reproduction, evolving life forms crossed to developing multicellular organisms from single celled (unicellular) organisms

18. 17–3 Evolution of Multicellular Life
Precambrian Time- life existed only in the sea
B. Paleozoic Era- rich with evidence of many types of marine life
Mesozoic Era- increasing dominance of dinosaurs, appearance of flowering plants
D. Cenozoic Era- mammals evolved adaptations that allowed them to live in various environments, on land, water and air

19. Geologic Time Scale with Key Events
Section 17-3
Era
Period
Time
(millions of years ago)
Key Events
Cenozoic
Mesozoic
Paleozoic
Precambrian
Time
Quaternary
Tertiary
Cretaceous
Jurassic
Triassic
Permian
Carboniferous
Devonian
Silurian
Ordovician
Cambrian
1.8–present
65–1.8
145–65
208–145
245–208
290–245
363–290
410–363
440–410
505–440
544–505
650–544
Glaciations; mammals increased; humans
Mammals diversified; grasses
Aquatic reptiles diversified; flowering plants; mass extinction
Dinosaurs diversified; birds
Dinosaurs; small mammals; cone-bearing plants
Reptiles diversified; seed plants; mass extinction
Reptiles; winged insects diversified; coal swamps
Fishes diversified; land vertebrates (primitive amphibians)
Land plants; land animals (arthropods)
Aquatic arthropods; mollusks; vertebrates (jawless fishes)
Marine invertebrates diversified; most animal phyla evolved
Anaerobic, then photosynthetic prokaryotes; eukaryotes, then multicellular life

20. 17–4 Patterns of Evolution
A. Mass Extinctions- dinosaurs
B. Adaptive Radiation- species evolved into several different forms that live in different ways
C. Convergent Evolution- unrelated organisms come to resemble one another

21. 17–4 Patterns of Evolution
D. Coevolution- process by which two species evolve in response to changes in each other over time
E. Punctuated Equilibrium- patterns of long, stable periods interrupted by brief periods of more rapid change
Gradualism- patterns of slow, gradual change

22. 17–4 Patterns of Evolution
F. Developmental Genes and Body Plans- changes in developmental genes, revealing major news about evolution of life

23. Flowchart Species Go to Section: that are Unrelated Related form in
under
under in in
Inter-relationshiops
Similar environments
Intense environmental pressure
Small populations
Different environments
can undergo
can undergo
can undergo
can undergo
can undergo
Coevolution
Convergent evolution
Extinction
Punctuated equilibrium
Adaptive radiation
Go to Section:

24. Section 15-1
A Trip Around the World
While on his voyage around the world aboard the H.M.S. Beagle, Charles Darwin spent about one month observing life on the Galápagos Islands. There, he encountered some unique animals, such as finches and tortoises.

25. 1. On a sheet of paper, list five animals that you have encountered in the past two days.
2. How do these animals differ from the finches and tortoises of the Galápagos Islands? (Examine Figures 15–3 and 15–4 in your textbook.)
3. Propose a hypothesis to account for the differences between the animals that you observed and the finches and tortoises of the Galápagos Islands.

26. B. Darwin’s Observations 1. Patterns of Diversity
15–1 The Puzzle of Life’s Diversity
Section 15-1
A. Voyage of the Beagle
B. Darwin’s Observations
1. Patterns of Diversity
2. Living Organisms and Fossils
3. The Galápagos Islands
C. The Journey Home

27. Giant Tortoises of the Galápagos Islands
Pinta Island Intermediate shell
Hood Island
Saddle-backed shell
Pinta Island Intermediate shell

28. Figure 15–1 Darwin’s Voyage

29. My, How You’ve Changed!
Prior to the 1800s, life scientists knew that living things changed over generations. They just didn’t know how these changes were brought about.

30. 1. Divide a sheet of paper into two columns and title the first one Inherited Characteristics. Title the second column Acquired Characteristics. In the first column, list the characteristics that you believe you have always had. For example, you may have brown eyes or curly hair.

31. 2. In the second column, list your acquired characteristics
2. In the second column, list your acquired characteristics. For example, you may have learned how to play a musical instrument.
3. Which of the items in your lists do you think you might pass on to your children? Explain your answer

32. A. An Ancient, Changing Earth 1. Hutton’s Theory of Geological Change
15–2 Ideas That Shaped Darwin’s Thinking
A. An Ancient, Changing Earth
1. Hutton’s Theory of Geological Change
2. Lyell’s Principles of Geology

33. 15–2 Ideas That Shaped Darwin’s Thinking
B.Lamarck’s Theory of Evolution
1. Tendency Toward Perfection
2. Use and Disuse
3. Inheritance of Acquired Traits
4. Evaluating Lamarck’s Theory
C.Population Growth

34. Hutton’s Theory of Geological Change
In 1975, geologist James Hutton proposed that layers of rock form very slowly. Some rocks are moved up by forces beneath the Earth’s surface, others are buried. Resulting rocks, mountains, and valleys are then shaped by a variety of natural forces-including rain, heat and cold temperatures

35. Lyell’s Principles of Geology
Lyell’s work explained how awesome geological features could be built up or torn down over long periods of time.
His work influenced Darwin in two ways:
If the earth could change overtime, might life change as well?
He realized that it must have taken many, many years, earth must be very old

36. Movement of Earth’s Crust
As the surface erodes due to water, wind, waves, or glaciers, the older rock surface is exposed.
When part of Earth’s crust is compressed, a bend in a rock forms, tilting the rock layers.
New sediment is then deposited above the exposed older rock surface.
Sedimentary rocks form in horizontal layers

37. Lamarck’s Theory of Evolution 1. Tendency Toward Perfection
He proposed that all organisms are continually changing and acquiring features that help them live more successfully in their environment

38. 2. Use and Disuse
He proposed that organisms could alter the size or shape of particular organs by using their bodies in new ways.
Conversely, if a winged animal did not use its wings (ex. of disuse) the wings would decrease in size over generations and finally disappear

39. 3. Inheritance of Acquired Traits
Lamarck thought that acquired characteristics could be inherited
By this reasoning, if you spent much of your life lifting weights to build muscles, your children would inherit big muscles, too.

40. 4. Evaluating Lamarck’s Theory
He was incorrect in many ways
Lamarck, like Darwin, did not know how traits are inherited or that behavior has no effect on its inheritable characteristics
One of first to develop scientific theory of evolution and realize that organisms are adapted to their environment

41. Figure 15–7 Lamarck’s Theory of Evolution

42. 15–3 Darwin Presents His Case
A. Publication of On the Origin of Species
Darwin(1859)proposed a mechanism for evolution called natural selection
Continuous for millions of years and continues in all living things
Others strongly opposed

43. 15–3 Darwin Presents His Case
B. Natural Variation and Artificial Selection
Natural variation is the differences among individuals of a species, is found in all types of organisms
Artificial Selection occurs through a technique called selective breeding, that would determine which individuals to use for breeding based on the natural variation that was found

44. 15–3 Darwin Presents His Case
C.Evolution by Natural Selection
The Struggle for Existence- means that members of each species compete regularly to obtain food, living space, an other necessities of life

45. 15–3 Darwin Presents His Case
C. Evolution by Natural Selection
2. Survival of the Fittest
Fitness- the ability of an individual to survive and reproduce in its specific environment
Adaptation- is any inherited characteristics that increase an organism’s chance of survival

46. 15–3 Darwin Presents His Case
C. Evolution by Natural Selection
2. Survival of the Fittest
Individuals that are better suited to their environment-that is, with high levels of fitness-survive and reproduce most successfully

47. 15–3 Darwin Presents His Case
C. Evolution by Natural Selection
2. Survival of the Fittest
Over time, natural selection results in changes in the inherited characteristics of a population. These changes increase a species’ fitness in it’s environment

48. 15–3 Darwin Presents His Case
C. Evolution by Natural Selection
Descent With Modification
Each living species has descended, with changes, from other species over time

49. 15–3 Darwin Presents His Case
D. Evidence of Evolution
1. The Fossil Record
provided evidence that living things have been evolving for millions of years.
Sometimes fossil records includes similar, intermediate forms of a group of organisms that together suggest gradual modification over time

50. Evidence of Evolution includes The fossil record
Geographic distribution of living species
Homologous body structures
Similarities in early development
which is composed of
which indicates
which implies
which implies
Physical remains of organisms
Common ancestral species
Similar genes

51. D. Evidence of Evolution
2. Geographic Distribution of Living Species
Animals living under similar ecological conditions, were exposed to similar pressures of natural selection
Because of these similar selection pressures, different animals ended up evolving certain striking features in common

52. Figure 15–14 Geographic Distribution of Living Species
Beaver
Muskrat
Beaver and Muskrat
Coypu
Capybara
Coypu and Capybara

53. D. Evidence of Evolution
3. Homologous Body Structures
structures that have different mature forms and functions but develop from the same embryonic tissues

54. Figure 15–15 Homologous Body Structures
Turtle
Alligator
Bird
Mammals
Typical primitive fish

55. D. Evidence of Evolution
4. Similarities in Early Development
early stages, or embryos, of many animals with backbones are so similar that they can be hard to tell apart

56. E. Summary of Darwin’s Theory
Organisms in nature differ, some variation is inherited
Survival of the fittest
Natural Selection
Variation

57. 1. Make a list of physical traits that you think are influenced by genes. Then, write next to each trait whether you have the trait or not (e.g., a widow’s peak) or whether there are many variations of the trait (e.g., hair color).

58. 2. Are most of the traits you listed clear-cut or are they mostly traits that have many variations? Which traits in your list are difficult to categorize?

59. 3. Compare your list with that of another student
3. Compare your list with that of another student. Did he or she think of any traits that you missed? Why do you think some traits are clear-cut, while others are not?

60. 16–1 Genes and Variation A. Darwin’s Ideas Revisited
Without an understanding of heredity, Darwin was unable to explain two important factors. First, he did not know the source of the variation that was so central to his theory. Second, he could not explain how inheritable traits were passed from one generation to the next.

61. 16–1 Genes and Variation B. Gene Pools
is the combined genetic information of all the members of a particular population

62. 16–1 Genes and Variation C. Sources of Genetic Variation
Mutations- is any change in a sequence of DNA
Gene Shuffling- occurs during the production of gametes (23 chromosomes in sperm and 23 in egg=46 Zygote)
Crossing over- exchange of genetic material between chromosomes

63. 16–2 Evolution as Genetic Change
C. Genetic Drift
In small, populations, individuals that carry a particular allele may leave more descendants than other individuals, just by chance. Over time, a series of chance occurrences of this type can cause an allele to become common in a population

64. 16–2 Evolution as Genetic Change
D. Evolution Versus Genetic Equilibrium
Random Mating
Ensures that each individual has an equal chance of passing on it’s alleles

65. 16–2 Evolution as Genetic Change
D. Evolution Versus Genetic Equilibrium
Large Population
Important in maintaining genetic equilibrium
Genetic drift has less effect on large populations

66. 16–2 Evolution as Genetic Change
D. Evolution Versus Genetic Equilibrium
No Movement Into or Out of the Population
Keep gene pool together and separate of other populations

67. 16–2 Evolution as Genetic Change
D. Evolution Versus Genetic Equilibrium
No Mutations

68. 16–2 Evolution as Genetic Change
D. Evolution Versus Genetic Equilibrium
5. No Natural Selection

69. Sample of Original Population

70. Sample of Original Population
Founding Population A
Founding Population B

71. Sample of Original Population Descendants
Founding Population A
Founding Population B

72. Country Cousin/City Cousin
What happens when a population or group of living things is divided into two separate groups in two separate environments? To understand what goes on, think about someone who lives in another part of the United States or in another country.

73. 1. Make a list of everyday things that this person encounters that you don’t. For example, does he or she eat different kinds of food? Does he or she live in a climate different from yours?
2. All humans are the same species. What might happen if groups of humans were separated for millions of years in very different environments, such as those you have just described?

74. 16–3 The Process of Speciation
A. Isolating Mechanisms
As new species evolve, populations become reproductively isolated from each other
1. Behavioral Isolation- two populations are capable of interbreeding, but differences in courtship rituals

75. 2. Geographic Isolation- two populations are separated by geographic barriers such as rivers, mountains, or bodies of water
3. Temporal Isolation- two or more species reproduce at different times (orchid in the rainforest)

76. 16–3 The Process of Speciation
B. Testing Natural Selection in Nature
1. Variation- Grant’s concluded that there is a great deal of variation of inheritable traits among the Galopagos finches
2. Natural Selection- when food for finches was scarce, individuals with the largest beaks were more likely to survive
3. Rapid Evolution- changes in beaks occurred over decades instead of thousands of years

77. 16–3 The Process of Speciation
C. Speciation of Darwin’s Finches
1. Founders Arrive
2. Separation of Populations
3. Changes in the Gene Pool
4. Reproductive Isolation
5. Ecological Competition
6. Continued Evolution

78. 16–3 The Process of Speciation
C. Speciation of Darwin’s Finches
1. Founders Arrive
Once they arrived on one of the island, they managed to survive and reproduce

79. 16–3 The Process of Speciation
C. Speciation of Darwin’s Finches
2. Separation of Populations
Species crossed islands

80. 16–3 The Process of Speciation
C. Speciation of Darwin’s Finches
Changes in the Gene Pool
Over time natural selection would have caused that population to evolve larger beaks, forming a separate population

81. 16–3 The Process of Speciation
C. Speciation of Darwin’s Finches
Reproductive Isolation
Gene pools of the two bird populations remain isolated from each other

82. 16–3 The Process of Speciation
C. Speciation of Darwin’s Finches
Ecological Competition
Overtime, species evolve in a way that increases the differences between them

83. 16–3 The Process of Speciation
C. Speciation of Darwin’s Finches
Continued Evolution
Over many generations, it produced the 13 finch species found there today

84. Reproductive Isolation
results from
Isolating mechanisms
which include
Behavioral isolation
Temporal isolation
Geographic isolation
produced by
produced by
produced by
Behavioral differences
Different mating times
Physical separation
which result in
Independently evolving populations
which result in
Formation of new species

85. The End