Transcript Ch 14 Evolution

Chapter 14 Principles of Evolution
• How Did Evolutionary Thought Evolve?
• Early Biological Thought Did Not Include the Concept
of Evolution
• Exploration of New Lands: Staggering Diversity of Life
• Fossil Discoveries: Life Had Changed Over Time
– The Grand Canyon of the Colorado River
F14.1
– Types of fossils
(F14.2 p. 266)
– Fossils of extinct organisms
(F14.3 p. 267)
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eggs in nest
fossilized feces
(coprolites)
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bones
footprints
skin impression
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How Did Evolutionary Thought Evolve?
• Some Scientists Devised Nonevolutionary Explanations
for Fossils
• A Few Scientists Speculated That Life Had Evolved
• Geology Provided Evidence That:
– Earth Is Exceedingly Old
– Gradual Change Over a Long Time Produces Large Differences
• Some Pre-Darwin Biologists Proposed Mechanisms for
Evolution
• Darwin and Wallace Proposed a Mechanism of
Evolution
– Darwin’s finches, residents of the Galapagos Islands
(F14.4 p. 269)
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Large ground finch, beak
suited to large seeds
Warbler finch, beak
suited to insects
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Small ground finch, beak
suited to small seeds
Vegetarian tree finch, beak
suited to leaves
How Does Natural Selection Work?
•A flowchart of evolutionary reasoning
(F14.5 p. 272)
Potential for
rapid reproduction
Relatively constant resources
and population size over time
Competition for survival
and reproduction
Variability in
structures and behaviors
NATURAL SELECTION:
On the average, the fittest
organisms leave the most offspring
Observation
Conclusion based on observation
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Some variability
is inherited
EVOLUTION:
The genetic makeup of the population
changes over time,
driven by natural selection
14.2 How Does Natural
Selection Work?
• 14.2.1 Modern Genetics Confirmed
Darwin’s Assumption of Inheritance
• 14.2.2 Natural Selection Modifies
Populations Over Time
– Figure 14.6 The evolution of the horse
(p. 272)
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Pliohippus
5
Hipparion
Archaeohippus
Anchitherium
Merychippus
Mesohippus
forefoot
tooth
25
35
Hyracotherium
Paleotheres
50
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browsing
millions of years ago
1
grazing
Equus
0
How Do We Know That Evolution
Has Occurred?
• Fossils Provide Evidence of Evolutionary
Change Over Time
• Comparative Anatomy Gives Evidence of
Descent with Modification
– Homologous Structures Provide Evidence of
Common Ancestry
(F14.7 p. 274)
– Functionless, Vestigial Structures Inherited from
Ancestors
(F14.8 p. 275)
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humerus
Pterodactyl
Dolphin
Dog
ulna
radius
carpals
metacarpals
phalanges
Human
Bird
Bat
FLYING
Seal
Sheep
Shrew
SWIMMING
RUNNING
GRASPING
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Salamander
Baleen whale
Boa constrictor
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How Do We Know That Evolution
Has Occurred?
• Some Anatomical Similarities from
Evolution in Similar Environments
• Analogous structures
(F14.9 p. 276)
• Similar Embryonic Stages Suggest
Common Ancestry
(F14.10 p. 276)
• Biochemical and Genetic Analyses Reveal
Relatedness Among Diverse Organisms
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What Is the Evidence That Populations
Evolve by Natural Selection?
• Artificial Selection Controlled Breeding
Modifies Organisms
(F14.11 p. 277)
• Evolution by Natural Selection Occurs Today
– When Fewer Predators Are Present, Brighter
Coloration Can Evolve
– Natural Selection Can Lead to Pesticide Resistance
– Experiments Can Demonstrate Natural Selection
– Selection Acts on Random Variation to Favor the
Traits That Work Best in Particular Environments
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What Is the Evidence That
Populations Evolve by
Natural Selection?
• Evolution by Natural Selection Occurs Today
– When Fewer Predators Are Present, Brighter
Coloration Can Evolve
– Natural Selection Can Lead to Pesticide Resistance
Activity 14.2
– Experiments Can Demonstrate Natural Selection
– Selection Acts on Random Variation to Favor the Traits
That Work Best in Particular Environments
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