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Concept 1.4: Evolution accounts for life's unity and diversityThe history of lifeIs a saga of a changing Earth billions of years old. Figure 1.17. Theodosius Dobzhansky.
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1. Descent with Modification A Darwinian View of Life Chapter 22
A.P. Biology
Liberty Senior High School
Rick L. Knowles
3. Theodosius Dobzhansky Nothing in biology makes sense except in the light of evolution.
The American Biology Teacher (1973)
4. Overview: Darwin Introduces a Revolutionary Theory
A new era of biology began on November 24, 1859
The day Charles Darwin published On the Origin of Species by Means of Natural Selection
5. Concept 22.1: The Darwinian revolution challenged traditional views of a young Earth inhabited by unchanging species
In order to understand why Darwins ideas were revolutionary
We need to examine his views in the context of other Western ideas about Earth and its life
6. The historical context of Darwins life and ideas
7. The Scale of Nature and Classification of Species The Greek philosopher Aristotle
Viewed species as fixed and unchanging
The Old Testament of the Bible
Holds that species were individually designed by God and therefore perfect
Intelligent Design
8. Carolus Linnaeus
Interpreted organismal adaptations as evidence that the Creator had designed each species for a specific purpose
Was a founder of taxonomy, classifying lifes diversity for the greater glory of God
Viewed species similarities not as evolutionary relationship, but as patterns of creation.
9. Fossils, Cuvier, and Catastrophism The study of fossils
Helped to lay the groundwork for Darwins ideas
Fossils are remains or traces of organisms from the past
Usually found in sedimentary rock, which appears in layers or strata
10. Paleontology, the study of fossils
Was largely developed by French scientist Georges Cuvier
Observed that upper strata were younger and lower strata were older
Noticed that new species would appear in an older strata and then disappear in a newer strata.
Cuvier opposed the idea of gradual evolutionary change
And instead advocated catastrophism, speculating that each boundary between strata represents a catastrophe (flood or drought).
11. Theories of Gradualism Gradualism
Is the idea that profound change can take place through the cumulative effect of slow but continuous processes.
1795, James Hutton proposed that Earths geologic features could be explained by gradual mechanisms currently operating (ex. valleys are created by rivers)
12. Geologists Hutton and Charles Lyell
Perceived that changes in Earths surface can result from slow continuous actions still operating today
Lyell proposed uniformitarianism same geologic processes are operating today as in the past and at the same rate.
Exerted a strong influence on Darwins thinking
13. One of the First Ideas of Evolution Lamarck compared species today with the fossil record.
1809, hypothesized that species evolve through use and disuse and the inheritance of acquired traits.
Organisms have an innate drive to become more complex.
But the mechanisms he proposed are unsupported by evidence
15. Darwin and the HMS Beagle During his travels
Darwin observed and collected many specimens of South American plants and animals
Darwin observed various adaptations of plants and animals
That inhabited many diverse environments
17. Name Two (2) Observations that Darwin Made Leading to His Theory.Name One (1) Observation Weve Since Made About the Natural World.
18. Darwins Observations about Evolution 1. Fossil Record: noticed that the fossils of South America resembled living species of that continent.
Example: Glyptodon related to modern armadillo?
19. Glyptodon
20. Darwins Observations of Evolution 2. Biogeography plants and animals in temperate regions of South America resemble tropical species in South America than the temperate species in Europe.
The distribution of life across similar climates is not always the same; (climate alone is not causing diversity).
Closely related species are found in same geographic region.
21. Different geographic regions, different mammalian brands
Have evolved independently from different ancestors
22. Charles Darwin, 1835, Galapagos
23. Whats so special about a bunch of islands?National Geographic SeriesGalapagos, Tape #254
25. Darwins Finches
26. The Galapagos Archipelago
27. Bartoloma Island
28. Isabela Island
29. Darwin proposed that natural selection
Could enable an ancestral species to split into two or more descendant species, resulting in a tree of life
31. Seen one tortoise, youve seen them all?
32. Galapagos Tortoise Distribution
33. Galapagos Tortoise-Env. Club 2008, Omaha Zoo
34. Darwins Focus on Adaptation Years later, Darwin reassessed all that he had observed during the voyage of the Beagle
He began to perceive adaptation to the environment and the origin of new species as closely related processes
35. Alfred Russel Wallace, 1823-1913
39. Other Observations about Evolution 3. Artificial Selection - humans have modified other species over many generations by selecting and breeding individuals that possess desired traits
40. The Origin of Species articulated two main points
Descent with modification
Natural selection
41. Natural Selection Darwin proposed natural selection
As the mechanism for evolutionary adaptation of populations to their environments
42. Natural selection is the evolutionary process that occurs
When a populations heritable variations are exposed to environmental factors that favor the reproductive success of some individuals over others.
43. The Origin of Species Darwin developed two main ideas
Evolution explains lifes unity and diversity
Natural selection is a cause of adaptive evolution
The phrase descent with modification
Summarized Darwins perception of the unity of life
States that all organisms are related through descent from an ancestor that lived in the remote past
44. Elephant Phylogeny
45. Summary of Natural Selection Natural selection is differential success in reproduction
That results from the interaction between individuals that vary in heritable traits and their environment
If an environment changes over time
Natural selection may result in adaptation to these new conditions
46. Over time natural selection can produce an increase
In the adaptation of organisms to their environment
47. Concept 22.3: Darwins theory explains a wide range of observations
Darwins theory of evolution
Continues to be tested by how effectively it can account for additional observations and experimental outcomes
Natural Selection in Action Evolution continues today!
Guppies
HIV
Humans
48. Differential Predation in Guppy Populations Researchers have observed natural selection
Leading to adaptive evolution in guppy populations
50. The Evolution of Drug-Resistant HIV In humans, the use of drugs
Selects for pathogens that through chance mutations are resistant to the drugs effects
Natural selection is a cause of adaptive evolution
51. Anatomy of HIV
52. Inside HIV
53. Researchers have developed numerous drugs to combat HIV
But using these medications selects for viruses resistant to the drugs
54. New Evidence that Darwin Did Not Have How old did most 19th Century people believe the Earth was?
About 6,000 years old (Cuviers young Earth)
1. Age of the Earth- 4.5 billion year old. Better dating techniques than in Darwins time; more complete fossil record.
55. 2. Transitional Species Have intermediate characteristics of two groups of animals may represent a link in evolution (missing link?).
Changes in structures may be small difficult to identify in fossils.
Species replaced quickly not common in fossil record.
56. Archaeopteryx (150 million years ago)
57. Archaeopteryx
58. Archaeopteryx at the KU Natural History Museum
59. Evolution Happens in Small Steps Show me the frogs!
Discover- Weird Nature: Marvelous Motion, tape #55
60. Other Transitional Examples?
61. A Walking Whale?
62. Transitional Skulls
63. Rodhocetus Foot
64. Transitional Diatoms in Yellowstone
65. 3. Vestigial Structures Existing structures that have no apparent function, but resemble structures of presumed ancestors.
Examples: human appendix; muscle set in humans for moving ears;
66. The Pelvis of a Whale
67. Evidence of Transitional Species Today! Vestigial Structure- blue whales with femurs?
Life of Mammals-Return to the Water video, tape #110
68. Vestigial Organs in Humans? Structures of little or no use but may represent historical remnants of structures that had important functions in ancestors.
69. Vermiform Appendix
70. Goosebumps?
71. Vomeronasal or Jacobsons Organ
72. JunkDNA; L-gulonolactone oxidase gene
73. Extra Ear Muscles auriculares muscles
74. Plantaris Muscle 9% dont have it
75. Wisdom Teeth mandible becoming smaller
76. Third Eyelid Plica semilunaris
77. Darwins (Auricular) Tubercle only 10.4% have it.
78. Coccyx
79. Four-Finned Dolphin; Oct, 2006
80. Four-Finned Dolphin; Oct, 2006
81. Show me more vestigial structures! Do snakes have feet?
The story of boas and pythons.
82. 4. Anatomical Homologies Homologous structures between organisms
Are anatomical resemblances that represent variations on a structural theme that was present in a common ancestor
83. Homology Homologous Structures structures in different species that are similar because of commons ancestry.
84. Sophie and a Mosasaur
85. Analogous Structures similarity in structures due to adaptations from similar evolutionary pressures (convergent evolution) and not a common ancestor. Analogy
86. The products of natural selection
Are often exquisite adaptations of organisms to the special circumstances of their way of life and their environment
87. 5. Comparative Embryology
Reveals additional anatomical homologies not visible in adult organisms
88. Show me an example of homologous structures! Compare a human hand and bat wing.
Life of Mammals- Life in the Trees video, tape #110
89. 6. Molecular Homologies Biologists observe homologies among organisms at the molecular level
Genes and proteins that are shared among organisms inherited from a common ancestor.
90. Darwins Theory of Evolution Natural selection is the driving force of changes within species populations.
91. Can we see evolution? Weiner, J. 1994. The Beak of the Finch. Knopf, New York.
The video What Darwin Never Saw
92. I want to see evolution in action! Scientific American Frontiers-Voyage to the Galapagos, 2000, VT 551.4 SCI