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Chapter 5
Biological Evolution
Chapter Outline:
I.
Evidence of Biological and Natural Selection
a. Darwinian Synthesis
II.
Variation and Inheritance of Traits
a. Modern Genetics: Genes, Chromosomes, and DNA
b. Mutations, Adaptations and Random Factors
c. Molecular Evolution and Molecular Clocks
III. Speciation
a. Speciation Processes
IV. Phylogenetics: Reconstructing Evolutionary History
V.
Evolutionary Patterns and Extinction
a. Irreversibility of Evolution
b. Convergent Evolution
c. Adaptive Radiations
d. Increase in Body Size
e. Heterochrony
f. Assymetry
g. Extinction
Key Terms:
evolution
natural selection
homologous structures
vestigial structures
adaptation
genetics
DNA (deoxyribonucleic acid)
genes
molecular clock
phylogeny
phyletic gradualism
punctuated equilibrium
cladogram
synapomorphies
adaptive radiation
mass extinctions
In-Class Activities:
Instructor Notes for In-Class Activity 1
Title:
How fast does evolution proceed? Phyletic Gradualism vs. Punctuated
Equilibrium.
Time:
5-10 minutes prep; 45– 60 minutes in class (or can assign research
between class periods)
Materials:
Internet required. Print worksheets as handouts.
Handouts:
A list of questions for students to research and discuss. Information on
Phyletic Gradualism and Punctuated Equilibria can be found in their
textbook and at the following websites.
http://www.youtube.com/watch?v=fVPadCMKJ_8
http://www.blackwellpublishing.com/ridley/a-z/Phyletic_gradualism.asp
http://pespmc1.vub.ac.be/Punctueq.html
Procedures:
A list of questions for students to research and discuss using
recommended websites.
First, have the students read the section in their textbook titled
“Speciation Rates” to contrast and compare the models of Phyletic
Gradualism vs. Punctuated Equilibrium.
Next, ask the students in groups of 3-4 watch the following video clip to
strengthen their knowledge of the differences between Phyletic
Gradualism vs. Punctuated Equilibrium.
http://www.youtube.com/watch?v=fVPadCMKJ_8
At this point the students should have a general idea as to the differences
between the two models for speciation. Have the students in groups of 34 discuss, answer and write down their answers for the following three
questions. Students can use websites such as the following as references.
http://www.blackwellpublishing.com/ridley/a-z/Phyletic_gradualism.asp
http://pespmc1.vub.ac.be/Punctueq.html
1) How does the Punctuated Equilibrium model differ from that of
Phyletic Gradualism in terms of rates of speciation?
2) How can the Punctuated Equlibrium model help explain the
existence of missing links in the fossil record?
3) Would Charles Darwin support the model of Punctuated
Equilibrium or Phyletic Gradualism?
Next, have the students watch the following two videoclips:
http://www.youtube.com/watch?v=GOKW_7KajCU
http://www.youtube.com/watch?v=I2C-3PjNGok
Have the students answer the following questions:
4) Charles Darwin predicted that transitional fossils would be
discovered. Does the fossil record for fish and whales confirm or
reject Darwin’s prediction?
5) In the 2nd video clip a wolf-like creature (with a complete set of
leg bones) was found with a whale-like ear. What did the
scientist, Dr. Gingrich feel is the best explanation for this fossil
find?
6) Does the discovery of more and more transitional fossils in the
rock record support the model of Punctuated Equilibrium or
Phyletic Gradualism, or both?
7) Do whales and fish swim in the same way? Why?
Student
Instructions: See above.
Specific
Suggestions:
The instructor should emphasize that students must be able to
differentiate between the models of Phyletic Gradualism and Punctuated
Equlibrium to perform well on a future test.
Objectives:
Students should be able to:
Clearly and concisely describe the differences between the Punctuated
Equilibrium and Phyletic Gradualism models of speciation.
Compare and contrast the Punctuated Equilibrium and Phyletic
Gradualism models of speciation predictions pertaining to “missing links
or transitional fossils”.
In-Class Activity 1: Handout
In the late 1800’s, Charles Darwin wrote that he believed evolution occurred slowly as a result of
a gradual accumulation of changes from one generation to another. He predicted that more and
more missing links would be found to support his view. This model of speciation, is known as
“Phyletic Gradualism”. In the early 1970’s a newer model for speciation called “Punctuated
Equilibrium” was introduced to the scientific mainstream by Niles Eldredge and Stephen Jay
Gould. Your goal today is to compare and contrast the two models, and to determine the
significance of the recent discoveries of the walking ancestors of fish and whales in terms of
supporting or debunking Darwin’s predictions that transitional fossils would be found.
First, read the section in your textbook titled “Speciation Rates” to contrast and compare the
models of Phyletic Gradualism vs. Punctuated Equilibrium.
Next, in groups of 3-4, watch the following video clip to strengthen your knowledge of the
differences between Phyletic Gradualism vs. Punctuated Equilibrium.
http://www.youtube.com/watch?v=fVPadCMKJ_8
At this point you should have a general idea as to the differences between the two models for
speciation. Discuss, answer and write down your group’s answers to the following three
questions. Students can use websites such as the following, as references.
http://www.blackwellpublishing.com/ridley/a-z/Phyletic_gradualism.asp
http://pespmc1.vub.ac.be/Punctueq.html
1) How does the Punctuated Equilibrium model differ from that of Phyletic Gradualism in
terms of rates of speciation?
2) How can the Punctuated Equlibrium model help explain the existence of missing links in
the fossil record?
3) Would Charles Darwin support the model of Punctuated Equilibrium or Phyletic
Gradualism?
Next, with your fellow group members, watch the following two videoclips:
http://www.youtube.com/watch?v=GOKW_7KajCU
http://www.youtube.com/watch?v=I2C-3PjNGok
Discuss and write down your groups answers to the following questions.
4) Charles Darwin predicted that transitional fossils would be discovered. Does the fossil
record for fish and whales confirm or reject Darwin’s prediction?
5) In the 2nd video clip a wolf-like creature (with a complete set of leg bones) was found
with a whale-like ear. What did the scientist, Dr. Gingrich feel is the best explanation for
this fossil find?
6) Does the discovery of more and more transitional fossils in the rock record support the
model of Punctuated Equilibrium or Phyletic Gradualism, or both?
7) Do whales and fish swim in the same way? Why?
Submit your answers to the seven questions to your instructor for grading. Your graded answers
will be handed back to you next week. Carefully go over your graded lab next week to prepare
for a test in the near future.
Instructor Notes for In-Class Activity 2
Title:
Evidence for Evolution: Vestigial Structures, Homologous Structures and
Analagous Structures.
Time:
5 – 10 Minutes prep; 40 – 60 minutes in class (or can assign research
between class periods)
Materials:
Print instruction sheets as handouts.
Handouts:
A list of questions for students to answer and discuss and recommended
websites. Information pertaining to vestigial structures, homologous
structures and analogous structures can be found at the following
websites.
http://www.bookrags.com/research/vestigial-structures-wap
http://www.talkorigins.org/faqs/comdesc/section2.html
http://bioweb.cs.earlham.edu/9-12/evolution/HTML/live.html
http://encarta.msn.com/media_461553540_761554675_1_1/analogous_and_homologous_structures.html
http://web1.d25.k12.id.us/home/staff/rudeer/homoanalvestig.html
The section on “Darwinian Synthesis” in the textbook is also an excellent
reference for completing the questions contained within this in-class
exercise.
Procedures:
Hand out instruction sheets to students. Using the websites listed above
and the section on “Darwinian Synthesis” in the textbook to answer the
following questions.
1. Define the term “vestigial structures”. Do vestigial structures by
definition have absolutely no function for modern day organisms?
2. List five examples of vestigial structures. How do these
structures support the theory or evolution (that species change
with time)?
3. In humans, are men’s nipples and men and woman’s navels
considered to be vestigial structures? Explain your answer.
4. In humans, list two examples of vestigial structures that point to
our ancestor’s herbivorous ancestry.
5. In humans, what is a coccyx, and how might it be considered to
be a vestigial structure?
6. What are homologous structures? What are analogous structures?
How are they different?
7. Why are homologous and analogous organs thought to be
evidence for evolution?
8. Both penguins and seals have streamlined bodies; is this an
example of homologous or analogous structures? Explain.
9. From an evolutionary perspective, why do dogs, whales and
humans have the same arm bone structure?
10. Why do some whales have pelvises?
Afterwards have the students discuss how analogous organs, homologous
organs and vestigial structures can be used to support the theory of
evolution.
Student
Instructions: See above
Specific
Suggestions:
Objectives:
The instructor should emphasize that vestigial structures, homologous
organs, and analogous organs are important supporting evidence for
evolution, and that students should be familiar with several examples of
each. Knowledge of these will help students prepare for a future quiz or
exam.
Students should be able to:
List 2-3 examples of homologous organs, analogous organs and vestigial
structures.
Describe how homologous organs, analogous organs and vestigial
structures can be used to support the theory of evolution.
Describe two types of vestigial structures in humans, and their
evolutionary significance.
In-Class Activity 2: Handout
Vestigial structures, homologous organs and analogous organs are used to support the theory of
evolution. The purpose of this in-class exercise is for you to become familiar with the
definitions of these terms, examples of each, and the reasons why they support the theory of
evolution. The section of your book called “Darwinian Synthesis” is an excellent reference
when answering the following 10 questions. Also, the following websites are also useful
references.
http://www.bookrags.com/research/vestigial-structures-wap
http://www.talkorigins.org/faqs/comdesc/section2.html
http://bioweb.cs.earlham.edu/9-12/evolution/HTML/live.html
http://encarta.msn.com/media_461553540_761554675_1_1/analogous_and_homologous_structures.html
http://web1.d25.k12.id.us/home/staff/rudeer/homoanalvestig.html
Using the above references, answer the following questions.
1) Define the term “vestigial structures”. Do vestigial structures by definition have
absolutely no function for modern day organisms?
2) List five examples of vestigial structures. How do these structures support the theory or
evolution (that species change with time)?
3) In humans, are men’s nipples and men and woman’s navels considered to be vestigial
structures? Explain your answer.
4) In humans, list two examples of vestigial structures that point to our ancestor’s
herbivorous ancestry.
5) In humans, what is a coccyx, and how might it be considered to be a vestigial structure?
6) What are homologous structures? What are analogous structures? How are they
different?
7) Why are homologous and analogous organs thought to be evidence for evolution?
8) Both penguins and seals have streamlined bodies, is this an example of homologous or
analogous structures? Explain.
9) From an evolutionary perspective, why do dogs, whales and humans have the same arm
bone structure?
10) Why do some whales have pelvises?
In your own time today, when you are online, you may want to do a Google search and read
about additional examples of homologous organs, analogous organs and vestigial structures.
Spending a little time doing this today may help you to prepare for a quiz next week.