Download Variations in the Clam Species Clamys sweetus

Variations in the
Clam Species Clamys
sweetus
1
Learning Target
• I can describe how natural
selection preserves favorable
traits
• Create a new title/thread “Clamys
sweetus”
• Update your table of contents
2
Entry Task
•In your notebook, write 5
words or phrases that
come to mind when you
hear the term “Natural
Selection”
3
Entry Task
•In groups of 4, take turns
sharing your lists.
•Describe why you chose
each word/phrase.
•Choose two words/phrases
to share with the class.
4
What is the role of natural
selection in evolution?
Comment on each statement.
Which one do you agree with?
Why?
5
Clamys Sweetus
•Read the Introduction
•Descent with modification:
natural selection favors some
variations resulting in them
becoming more common in
the next generation.
6
Clamys Sweetus
•Without opening the bags, and
without squeezing the clams,
observe the two strains of
clamys sweetus.
•Answer #1,2,3 in your packet.
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Clamys Sweetus
•Read “Observations of Clamys
sweetus” p. 2
•Using Chart 1, you will be
comparing pairs of clams (1
strain R and 1 strain M) to
determine if one clam has a
stronger shell.
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Clamys Sweetus
•Follow Procedures 1-1 thru 16.
•Record your results in Chart 2
(1-7)
•Put your group’s results on the
board.
9
Clamys Sweetus
•Using the class data, complete
the Analysis section (steps
4,5,6)
•Read “Setting the Scene”
•Answer step 7
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Clamys Sweetus
•Step 5: Why is it important to use
class data and not just the data
obtained by an individual team?
Class results are more reliable
because there are more trials. A
larger sample size leads to
increased precision and more
accurate data.
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Clamys Sweetus
•Step 6: Is there a difference in
shell strength between the two
varieties? Support your
answer with data.
12
Clamys Sweetus
•Step 7a: The arthropod is able
to crack open only relatively
weak clam shells. Which
variety might the arthropod
seek out as it hunts for food?
13
Clamys Sweetus
•Step 7b: How might this
feeding preference affect the
numbers of the two varieties in
this and future populations of
C.sweetus?
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Wrap-Up
• What trait was “selected for” in this
activity?
• How does this activity relate to our
learning target?
• How do you think this learning target
fits in with our chapter goal of
answering the question “What are
the underlying biological
mechanisms of evolution?”
15
Exit Ticket
• Complete and return the exit
ticket before you leave!
16
Clamys Sweetus Day 2
•We are going to investigate the
hypothesis that shell color and
hardness are related.
•Follow 2-1 thru 2-3 to gather
data
•Put your data on the board.
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Clamys Sweetus Day 3
• A new color variation of Clamys Sweetus has
appeared – Brown
• Formulate a hypothesis about the ability of
brown clams to survive predation by the
predatory arthropod.
• Design an experiment to test your hypothesis.
• This is very similar to the type of prompt you
will see on the EOC!
• Complete #13 and #14
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Clamys Sweetus Day 3
• Question:
Could the presence of a few brown clams
eventually lead to a population that is
mostly brown clams?
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Clamys Sweetus Day 3
• Pocketmouse video
• Does fur color influence which pocket mouse
survives and which does not?
• Could the pocket mouse information apply to
C. sweetus?
• What do you need to know to make this
decision?
• Video
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Clamys Sweetus Day 3
 Could the pocket mouse information apply
to C. sweetus?
 If it does, what caused the brown color to
appear in the clam population?
 Complete the rest of the packet.
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