Build a Cladogram
CLASS SET
Purpose: Use derived characters to build a cladogram.
Investigative Question: What are the evolutionary relationships between a coyote, fish, frog, hawk, human, lizard, rabbit, and
snake?
Introduction:
Evolution biologists use derived characters, traits shared by some groups of organisms, to build cladograms. Cladograms are used
like family trees to show the evolutionary relationship between many extant species.
This is done by creating a table of traits, and comparing the traits of various extant species. The number of shared characteristics
indicates how closely related the species are to one another. This number can then be used to build a cladogram.
In this lab you will be presented with pieces of evidence for Cetacean Evolution in all 8 categories. You will then use this evidence to
support a claim about the evolution of aquatic mammals.
Procedure:
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Read the lab introduction.
Complete the pre-lab.
Get the pre-lab checked off.
Complete the derived characters table.
Get eh derived characters table checked off.
Complete the Venn diagram.
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It has been started for you, continue drawing circles to indicate the derived characters.
Get the Venn diagram checked off.
Draw a cladogram.
Get the cladogram checked off.
Complete the “Analysis” section of the answer sheet.
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Be as specific and detailed as possible.
Names: _______________________
Building a Cladogram- Answer Sheet
Period: _______________________
Pre-Lab: Make sure that you have read the lab introduction.
1.
What is a derived character?
2. What are the two parts of a cladogram, and what do they represent?
Derived Characters: Indicate which species have the following traits, then total up the total number of derived characters:
Trait
Coyote
Fish
Frog
Hawk
Spinal Cord
Four Limbs
Claws/Nails
Calcified Eggs
Feathers
Hair
Canine Teeth
Bipedal
Total Traits
Venn Diagram: Continue the Venn diagram that has been started for you.
Spinal Cord
Four limbs
Human
Lizard
Rabbit
Snake
Cladogram: Using the Venn diagram you created above draw a cladogram to demonstrate the relationship between a coyote,
fish, frog, hawk, human, lizard, rabbit, and snake:
Analysis:
1.
What is the outgroup on this cladogram? How many derived characters did this group share with the others?
2. Which two species are the most distantly related? How can you tell?
3. Which species are most closely related on this cladogram? How can you tell? (HINT: there are two sets)
4. Which species share the derived character of calcified eggs?
5. What selective pressure may have caused the development of calcified eggshells? Explain what caused this selective
pressure, and why it selected for calcified eggshells.