Transcript Assessment - What Evidence do You Accept?

Natural Selection Problem
Goals: Students will be able to
1. Design a testable hypothesis
2. Analyze and interpret a simulation
about an ecological problem
3. explain how evolution actually works.
Hummingbird Video
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What are the four
processes required
for natural selection?
Sex and the Single Guppy
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Introduction to the Question
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

In pools with many predators, male
guppies are drab colored.
In pools with few predators, male
guppies have bright coloration.
Why is there a difference?
Guppy Gallery
Design a Testable Hypothesis


In your groups, develop a hypothesis
to explain the observed pattern of
fish coloration in the pools.
Design an experiment to test your
hypothesis.
Experimental Simulation


Before each simulation begins, predict
what will happen, based on your
hypothesis.
As the simulation is running, your
group will record data for each
generation.
Simulation 1
Results - Simulation 1
Data Table - Simulation 1
Simulation 2
Results - Simulation 2
Data Table - Simulation 2
Data Analysis
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On your carbonless paper, plot a line graph
of the changing proportions of color
pattern over time.
What is the independent variable? Which
axis should you plot it on?
Which is the dependent variable? Which
axis should you plot it on?
Low Predation
High Predation
Analysis
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Do these data match your prediction
(support your hypothesis)?
Why or why not?
Questions for Discussion
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What determines the color pattern of an
individual guppy?
What role(s) does color play in guppy
survival and reproduction?
Explain the results in terms of fitness and
natural selection. Describe how sexual
selection and natural selection push in
opposite directions.
Questions for Assessment
(from Anderson et al., 2002)
A typical natural population of guppies consists of hundreds
of guppies. Which statement best describes the guppies of
a single species in an isolated population?
a.
b.
c.
d.
The guppies share all of the same characteristics and
are identical to each other.
The guppies share all of the essential characteristics
of the species; the minor variations they display don’t
affect survival
The guppies are all identical on the inside, but have
many differences in appearance.
The guppies share many essential characteristics, but
also vary in many features.
Student Responses on Midterm
(n=176)
70
60
% of Students
50
40
30
20
10
0
a
b
c
A nswer Choice
d
Questions for Assessment
(from Anderson et al., 2002)
Fitness is a term often used by biologists to explain the
evolutionary success of certain organisms. Which feature
would a biologist consider to be most important in
determining which guppies were the “most fit”?
a.
b.
c.
d.
large body size and ability to swim quickly away from predators
excellent ability to compete for food
high number of offspring that survived to reproductive age
high number of matings with many different females
Student Responses on Midterm
(n=176)
90
80
% of Students
70
60
50
40
30
20
10
0
a
b
c
A nswer Choice
d
Questions for Assessment
(from Anderson et al., 2002)
In guppy populations, what are the primary changes that
occur gradually over time?
a.
b.
c.
d.
The traits of each individual guppy within a population
gradually change.
The proportions of guppies having different traits within a
population change.
Successful behaviors learned by certain guppies are
passed on to offspring.
Mutations occur to meet the needs of the guppies as the
environment changes.
Student Responses on Midterm
(n=176)
80
70
% of Students
60
50
40
30
20
10
0
a
b
c
A nswer Choice
d