1. Evolution and Darwin

2. * Evolution
Is defined as the processes that have transformed life on earth from it’s earliest forms to the vast diversity that characterizes it today.
A change in the genes!!!!!!!!

3. SCI.9-12.B-5 - [Standard] - The student will demonstrate an understanding of biological evolution and the diversity of life.

4. *Old Theories of Evolution
Jean Baptiste Lamarck (early 1800’s) proposed:
“The inheritance of acquired characteristics” You would pass on to your children a skill you learned. If you played the piano, your children would be born playing the piano.
“Use – Disuse” He proposed that by using or not using its body parts, an individual tends to develop certain characteristics, which it passes on to its offspring.

5. “The Inheritance of Acquired Characteristics”
Example:
A giraffe acquired its long neck because its ancestor stretched higher and higher into the trees to reach leaves, and that the animal’s increasingly lengthened neck was passed on to its offspring.

6. *Lamarck’s Theory of Evolution
Use & Disuse - Organisms Could Change The Size Or Shape Of Organs By Using Them Or Not Using Them
Blacksmiths & Their Sons (muscular arms)
Giraffe’s Necks Longer from stretching)
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8. Charles Darwin
Influenced by Charles Lyell who published “Principles of Geology”.
This publication led Darwin to realize that natural forces gradually change Earth’s surface and that the forces of the past are still operating in modern times.

9. *Charles Darwin
Darwin set sail on the H.M.S. Beagle ( ) to survey the south seas (mainly South America and the Galapagos Islands) to collect plants and animals.
On the Galapagos Islands, Darwin observed species that lived no where else in the world.
These observations led Darwin to write a book.

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HMS Beagle’s Voyage
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The Galapagos Islands
Small Group of Islands 1000 km West of South America
Very Different Climates
Animals On Islands Unique
Tortoises
Iguanas
Finches
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The Galapagos Islands
Volcanic islands off the coast of South America
Island species varied from mainland species & from island-to-island species
Each island had long or short neck tortoises
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The Galapagos Islands
Finches on the islands resembled a mainland finch
More types of finches appeared on the islands where the available food was different (seeds, nuts, berries, insects…)
Finches had different types of beaks adapted to their type of food gathering
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20. *Charles Darwin
Wrote in 1859: “On the Origin of Species by Means of Natural Selection”
Two main points:
1. Species were not created in their present form, but evolved from ancestral species.
2. Proposed a mechanism for evolution: NATURAL SELECTION

21. *Natural Selection
Individuals with favorable traits are more likely to leave more offspring better suited for their environment.
Example:
English peppered moth (Biston betularia)
- light and dark phases

22. *Darwin’s 5 points Population has variations.
Some variations are favorable.
More offspring are produced than survive
Those that survive have favorable traits.
A population will change over time.

23. SCI.9-12.B-5.1 - [Indicator] - Summarize the process of natural selection.

24. *Artificial Selection
The selective breeding of domesticated plants and animals by man.
Question:
What’s the ancestor of the domesticated dog?
Answer: WOLF

26. *Evidence of Evolution
1. Biogeography:
Geographical distribution of species. EX. Most marsupials live in Australia.
2. Fossil Record:
Fossils and the order in which they appear in layers of sedimentary rock tells us the order that they appeared on earth (strongest evidence).

28. Eastern Long Necked Turtle

29. *Evidence of Evolution
3. Taxonomy:
Classification of life forms.
4. Anatomy:
Structures that are similar because of common ancestry (comparative anatomy)
Vestigial structures (remnant or leftover) structures that now have no function (human appendix)

30. Homologous Body Structures
Scientists Noticed Animals With Backbones (Vertebrates) Had Similar Bone Structure
May Differ In Form or Function
Limb Bones Develop In Similar Patterns
Arms, Wings, Legs, Flippers 30 30

31. Homologous Structures

32. Homologous Body Structures
Structures That Have Different Mature Forms But Develop From The Same Embryonic Tissues
Strong Evidence That All Four-Limbed Animals With Backbones Descended, With Modification, From A Common Ancestor
Help Scientist Group Animals 32 32

33. Homologous Body Structures
Not All Serve Important Functions
Vestigial Organs
Appendix In Man
Legs On Skinks 33 33

34. Analogous Structures
Structures that do not have a common origin but have a common function.

36. SCI.9-12.B [Indicator] - Exemplify scientific evidence in the fields of anatomy, embryology, biochemistry, and paleontology that underlies the theory of biological evolution.

37. *Evidence of Evolution
5. Comparative embryology:
During the early development of organisms very similar structures appear in different organisms. Ex. At one point, humans have gill slits and webbed fingers.
6. Molecular biology:
DNA and proteins (amino acids) cow insulin was once used to treat humans with diabetics

38. Similarities In Embryonic Development
Evidence for Evolution - Comparative Embryology
Similarities In Embryonic Development

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Human Fetus – 5 weeks
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Chicken
Turtle
Rat
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41. Similarities in DNA Sequence

42. *
Population
A localized group of individuals belonging to the same species.
Species
A group of populations whose individuals have the potential to interbreed and produce viable, fertile offspring.

43. Evolution of pesticide resistance in response to selection
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44. *Gene Pool
The total collection of genes in a population at any one time.

45. *Microevolution
A change in a population’s gene pool over a secession of generations.
Evolutionary changes in species over relatively brief periods of geological time.

46. *Five Causes of Microevolution
1. Genetic drift:
Change in the gene pool of a small population due to chance.
Two examples:
a. Bottleneck effect
b. Founder effect

47. *a. Bottleneck Effect
Genetic drift (reduction of alleles in a population) resulting from a disaster that drastically reduces population size.
Examples:
1. Earthquakes
2. Volcanoes

48. *b. Founder Effect
Genetic drift resulting from the colonization of a new location by a small number of individuals.
Results in random change of the gene pool.
Example:
1. Islands (first Darwin finch)

49. Simulation of Genetic Drift

50. SCI.9-12.B-5 The student will demonstrate an understanding of biological evolution and the diversity of life.
SCI.9-12.B [Indicator] - Explain how genetic variability and environmental factors lead to biological evolution.

51. *Five Mechanisms of Microevolution
2. Gene Flow:
The gain or loss of alleles from a population by the movement of individuals or gametes.
Immigration or emigration.

52. *Five Causes of Microevolution
3. Mutation:
Change in an organism’s DNA that creates a new allele.
4. Non-random mating:
The selection of mates other than by chance.
5. Natural selection:
Survival of the fittest

53. http://highered. mcgraw-hill

54. SCI.9-12.B-5 The student will demonstrate an understanding of biological evolution and the diversity of life.
SCI.9-12.B [Indicator] - Explain how genetic variability and environmental factors lead to biological evolution.

55. Modes of Action Natural selection has three modes of action:
1. Stabilizing selection
2. Directional selection
3. Diversifying selection
Number of
Individuals
Size of individuals
Small Large

56. 1. Stabilizing Selection
Acts upon extremes and favors the intermediate.
Number of
Individuals
Size of individuals
Small Large

57. Continuing our oyster example, very light-colored or very dark-colored oysters might be more frequently preyed upon by shore birds, simply because they are more obvious on the oyster bar; as a result, the intermediate hues become more common.

58. 2. Directional Selection
Favors variants of one extreme.
Number of
Individuals
Size of individuals
Small Large

59. If thicker-shelled oysters are more resistant to breakage than thinner-shelled oysters, crabs will be less able to prey upon them, and thicker-shelled oysters will be more likely to survive to reproduce

60. 3. Diversifying or Disruptive Selection
Favors variants of opposite extremes.
Number of
Individuals
Size of individuals
Small Large

61. This might happen in shallow water among rocks
This might happen in shallow water among rocks. Light-colored oysters are more camouflaged. (less easy for a predator to see) because they match the rock color. Dark-colored oysters blend into the shadows cast by the rocks. In this case, intermediate-colored oysters would be most heavily preyed upon by the crabs, and very light and very dark oysters would survive to reproduce.

62. Selection against small guppies results in an increase in average size
Evidence for Evolution – Evolution Observed
Selection against small guppies results in an increase in average size

63. SCI.9-12.B-5 The student will demonstrate an understanding of biological evolution and the diversity of life.
SCI.9-12.B [Indicator] - Explain how genetic variability and environmental factors lead to biological evolution.

64. Video clip on Selection

65. Selection against small guppies results in an increase in average size
Evidence for Evolution – Evolution Observed
Selection against small guppies results in an increase in average size

66. SCI.9-12.B-5 The student will demonstrate an understanding of biological evolution and the diversity of life.
SCI.9-12.B [Indicator] - Explain how genetic variability and environmental factors lead to biological evolution.

67. *Speciation
The evolution of new species. There is a new species when an organism cannot breed back to the parent species and produce fertile offspring.

68. *Reproductive Barriers
Any mechanism that stops two species from producing fertile and/or viable hybrid offspring.
Two barriers:
1. Pre-zygotic barriers
2. Post-zygotic barriers

69. *1. Pre-zygotic Barriers
a. Temporal or seasonal isolation:
Breeding occurs at different times for different species.
One species of a fish reproduces in the spring while another reproduces in late summer.

70. b. Habitat isolation:
Species breed in different habitats.
c. Behavioral isolation:
Little or no sexual attraction between species. Birds and courtship

72. *1. Pre-zygotic Barriers
d. Mechanical isolation:
Structural differences prevent gamete exchange.
e. Gametic isolation:
Gametes die before uniting with gametes of other species, or gametes fail to unite. Chromosome numbers don’t match up.

73. SCI.9-12.B-5 The student will demonstrate an understanding of biological evolution and the diversity of life.
SCI.9-12.B [Indicator] - Explain how genetic variability and environmental factors lead to biological evolution.

74. *2. Post-zygotic Barriers
a. Hybrid inviability:
Hybrid zygotes fail to develop or fail to reach sexual maturity.
b. Hybrid sterility:
Hybrid fails to produce functional gametes.
c. Hybrid breakdown:
Offspring of hybrids are weak or infertile.

75. *Interpretations of Speciation
Two theories:
1. Gradualist Model (Neo-Darwinian):
Slow changes in species overtime.
2. Punctuated Equilibrium:
Evolution occurs in spurts of relatively rapid change.

76. Figure 24.13 Gradualism model. Species descended from a common
ancestor gradually diverge
more and more in their
morphology as they acquire
unique adaptations.
Time
(a)
Punctuated equilibrium
model. A new species
changes most as it buds
from a parent species and
then changes little for the
rest of its existence.
(b)

77. *Convergent Evolution
Species from different evolutionary branches may come to resemble one another if they live in very similar environments.
Example:
1. Ostrich (Africa) and Emu (Australia).
2. Sidewinder (Mojave Desert) and
Horned Viper (Middle East Desert)

78. *Divergent Evolution
When a group of organisms starts living together but become separated into different habitats. They can evolve into different species

79. Darwin's finches are a clear and famous example of divergent evolution, in which an ancestral species radiates into a number of descendant species with both similar and different traits.

80. SCI.9-12.B-5 The student will demonstrate an understanding of biological evolution and the diversity of life.
SCI.9-12.B [Indicator] - Explain how genetic variability and environmental factors lead to biological evolution.

81. *Coevolution
Evolutionary change where two or more species change to depend on each other
Example:
1. Acacia ants and acacia trees
2. Humming birds and plants with flowers with long tubes

82. SCI.9-12.B [Indicator] - Explain how diversity within a species increases the chances of its survival.
SCI.9-12.B [Indicator] - Explain how genetic variability and environmental factors lead to biological evolution.

83. SCI.9-12.B [Indicator] - Use a phylogenetic tree to identify the evolutionary relationships among different groups of organisms.