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Biology Unit 7—Evolutionary Biology
1.
2.
3.
4.
5.
Early evolution of life
Theory of Evolution
Evidence for evolution
Genetic Equilibrium
Speciation
Chapters 14-16
Concepts: 14.1, 14.2, 14.3
Concepts: 15.1
Concepts: 15.2
Concepts: 16.1, 16.2
Concepts: 16.3
Key Terms
1. Evolution
2. Adaptive radiation
3. Divergent evolution
4. Convergent evolution
5. Fossil
6. Gene pool
7. Hardy-Weinberg Law
8. Natural selection
9. Embryology
10. Vestigial structure
11. Biogeography
12. Homologous structures
13. Analogous structures
14. Genetic variability
15. Mutation
16. Directional selection
17. Stabilizing selection
18. Disruptive selection
19. Speciation
20. Allopatric speciation
21. Sympatric speciation
22. Genetic drift
Recommended Work For Chapters 22-26
1. Concept Checks
2. Self-Quizzes
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Biology Unit 7—Evolutionary Biology
General review

Define the following:
o Evolution
o Microevolution
o Macroevolution
o Natural selection
Evidence for evolution
Evidence for evolution is provided by the following five scientific disciplines.
Describe and give examples for each of the five disciplines.
1. Paleontology
2. Biogeography
3. Embryology
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AP Biology Unit 7—Evolutionary Biology
4. Comparative anatomy, include homologous structures and analogous
structures.
5. Molecular biology
Natural Selection
Define the following
o Natural selection
o Adaptations
o Fitness
Darwin presented his theory for natural selection using the following arguments.
Explain each one.
1. Populations posses an enormous reproductive potential.
(Overproduction)
2. Genetic Variation
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Biology Unit 7—Evolutionary Biology
3. Resources are limited. (Struggle to Survive)
4. Individuals complete for survival.
5. There is variation among individuals in a population.
(Differential Reproduction)
6. Much variation is heritable. (What are the sources of genetic variation?)
7. Only the fit individuals survive. (Survival of the Fittest)
8. Evolution occurs as advantageous traits accumulate.
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Biology Unit 7—Evolutionary Biology
Natural selection may act upon a population in a variety of ways. Describe and explain
each one, include a graph that represents the type of selection.
1. Stabilizing selection
2. Directional selection
3. Disruptive selection
4. Artificial selection (no graph)
Sources of Variation
In order for natural selection to operate, there must be variation among
individuals in a population. Indeed, considerable variation exists in nearly all
populations. The variation arises from or is maintained by the following mechanisms.
Describe and explain each of the following.
1. Mutations
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Biology Unit 7—Evolutionary Biology
2. Sexual reproduction
a. Include the following
i. Genetic recombination/Crossing over
ii. Independent assortment of homologues
iii. Random joining of gametes
3. Balanced polymorphism, include heterozygote advantage
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Biology Unit 7—Evolutionary Biology
Causes of Changes in Allele Frequencies
Natural selection was the mechanism that Darwin proposed for evolution. With the
understanding of genetics, it became evident that factors other than natural selection can
change allele frequencies and thus promote evolution. These factors, together with
natural selection, are given below. Describe each one and explain how it causes changes
in allele frequencies.
1. Natural selection
2. Mutations
3. Gene Flow
4. Genetic drift, include the founder effect and bottleneck
5. Nonrandoming mating
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Biology Unit 7—Evolutionary Biology
Genetic Equilibrium
When the allele frequencies in a population remain constant from generation to
generation, the population is said to be in genetic equilibrium, or Hardy-Weinberg
equilibrium. At genetic equilibrium, there is no evolution. In order for equilibrium to
occur, the factors that normally change gene frequencies do not occur.
List the five conditions required for Hardy-Weinberg equilibrium:
1.
2.
3.
4.
5.
Speciation
A species is usually defined as a group of individuals capable of interbreeding.
Speciation, the formation of new species, occurs by the following processes. Describe
and explain each process and draw a graph to illustrate it.
1. Allopatric speciation
2. Sympatric speciation
3. Adaptive radiation
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Biology Unit 7—Evolutionary Biology
Maintaining Reproductive Isolation
If species are not physically separated by a geographic barrier, various mechanisms
commonly exist to maintain reproductive isolation and prevent gene flow. These
mechanisms may appear randomly (genetic drift) or may be the result of natural
selection.
There are two categories of isolating mechanisms. The first category, prezygotic
isolating mechanisms, consists of mechanisms that prevent fertilization. Describe each
of the following:
1. Habitat isolation
2. Temporal isolation
3. Behavioral isolation
4. Mechanical isolation
5. Gametic isolation
The second category, postzygotic isolating mechanisms, consists of mechanisms that
prevent the formation of fertile progeny. Describe each of the following:
1. Hybrid inviability
2. Hybrid sterility
3. Hybrid breakdown
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Biology Unit 7—Evolutionary Biology
Patterns of Evolution
The evolution of species is often categorized into the following four patterns. Describe
each of the following and draw a graph to illustrate each one.
1. Divergent evolution
2. Convergent evolution
3. Parallel evolution
4. Coevolution
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Biology Unit 7—Evolutionary Biology
Macroevolution
Define macroevolution:
The two distinct macroevolution theories listed below reflect different interpretations of
fossil evidence and explanations for the development of evolutionary history. Summarize
the two theories and draw a diagram to illustrate each one.
1. Gradualism
2. Punctuated equilibrium
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Biology Unit 7—Evolutionary Biology
The Origin of Life
The steps hypothesized to have led to the first primitive cell and the subsequent steps that
led to more complex living cells are outlined below. Describe each of the following:
1. The earth and its atmosphere formed
a. What was Earth’s early atmosphere like? List the possible contents.
2. The primordial seas formed.
a. As the earth cooled, gases condensed to produce primordial seas
consisting of water and minerals.
3. Complex molecules were synthesized
a. Describe the early formation of molecules.
b. What role did A.I. Oparin and J.B.S. Haldane have in forming
hypothesis’ pertaining to the origins of the first molecules?
c. Describe Stanley Miller’s experiment, and what is the significance of
his experiments?
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Biology Unit 7—Evolutionary Biology
4. Polymers and self-replicating molecules were synthesized
a. Monomers combined to form polymers. Some of these reactions may
occurred by dehydration synthesis (condensation) reactions, in which
polymers formed from monomers by the removal of water molecules.
5. Organic molecules were concentrated and isolated into protobionts.
a. Protobionts were the precursors of cells. They were able to carry out
chemical reactions enclosed within a border across which materials can be
exchanged, but were unable to reproduce. Borders formed in the same
manner as hydrophobic molecules aggregate to form membranes (as
phospholipids form plasma membranes).
b. Explain this concept microspheres, and coacervates.
6. Primitive heterotrophic prokaryotes formed.
a. Heterotrophs are living organisms that obtain energy by consuming
organic substances. Pathogenic bacteria, for example, are heterotrophic
prokaryotes.
b. The organic “soup” was a source of organic material for heterotrophic
cells. As these cells reproduce, composition for organic material increased.
Natural selection would favor those heterotrophs at obtaining food.
7. Primitive autotrophic prokaryotes were formed.
a. As a result of mutation, a heterotrophy gained the ability to produce its
own food. As an autotroph, this cell would be highly successful.
b. Autotrophs manufacture their own organic compounds using light energy
or energy from inorganic substances. Cyanobacteria (photosynthetic
bacteria), for example, are autotrophic prokaryotes that obtain energy and
manufacture organic compounds by photosynthesis.
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Biology Unit 7—Evolutionary Biology
8. Oxygen and the ozone layer formed and abiotic chemical evolution ended.
a. As a by-product of the photosynthetic activity of autotrophs, oxygen was
released and accumulated in the atmosphere. The interaction of UV light
and oxygen produced the ozone layer.
b. As a result of the formation of the ozone layer, incoming UV light was
absorbed, preventing it from reaching the surface of the earth. Thus, the
major source of energy for the abiotic synthesis of organic molecules and
primitive cells was terminated.
9. Eukaryotes formed (endosymbiotic theory)
a. Explain the endosymbiotic theory and cite the evidence for it.
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Biology Evolution Unit Essay Question #1
Explain how evolution occurs; make sure you discuss Darwin’s theory of natural
selection.
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Biology Evolution Unit Essay Question #2
Describe the process of speciation. Include a discussion of mechanisms that
maintain reproductive isolation.
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