Variations in the Clam Species Clamys sweetus

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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”

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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?

5Comment on each statement.Which one do you agree with? Why?

Clamys Sweetus

•Read the Introduction•Descent with modification: natural selection favors some variations resulting in them becoming more common in the next generation.

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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. 8

Clamys Sweetus

•Follow Procedures 1-1 thru 1-6.•Record your results in Chart 2 (1-7)•Put your group’s results on the board.

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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.

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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?

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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!

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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. 17

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 18

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?

• Video20

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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