Cladistics

SC.912.L.15.6 Discuss distinguishing characteristics of the domains and kingdoms of living organisms. (AA)

Purpose or Problem Statement:

Construct a cladogram.

Properly interpret and analyze cladogram in terms of recognizing the concepts of common ancestry and degrees of evolutionary relationship.

Materials (individual or per group):

Organism Cards and Linnaean Table (in student packet)

Clear (see-through) plastic bags – 7 per group

3 x 5 cards or sticky notes

Scissors

Printer paper

Color pencils or markers

Procedures:

1. Create a set of Name Cards by cutting 3x5 cards into 3 pieces until you have 8 pieces (sticky notes may be used instead).

2. Name each cut piece using the names on the Organism Cards provided

3. Examine the descriptions on the Organism Cards and the Linnaean table in order to select the two most similar organisms.

4. Put their name cards together in plastic bag 1.

5. Select the organism which is most like the ones you chose in step #3 and place this name card in bag 2.

6. Place bag 1, with its two name cards into bag 2.

7. Select the next most similar organism to the organisms in bag 2 and place its name card in bag 3.

8. Then add bag 2 (containing all the previous cards) into bag 3.

9. Repeat step 7 and 8 until all the name cards have been bagged.

10. Final ―nested‖ bags should look like this:

11. Place the 3-D Venn diagram on top of a piece of paper.

12. Record your data: Consider what characteristic is common to all the organisms in the bags. Write this characteristic at the end of a line connecting to the outermost organism. (Characteristic 1 in picture)

13. Consider the remaining bags of organism cards. What do all these organisms have in common? Write down that characteristic on another line connecting to the second largest Venn region.

14. Continue to examine the organisms in your bags and describe a common characteristic of the remaining organisms.

15. When you are done, you will have a branching tree diagram that looks a bit like a bonsai tree.

16. Remove the Name Cards from the bags and place in the appropriate line.

Observations/Conclusions:

1. Why do organisms resemble one another?

2. What does it mean when two organisms are very similar?

3. List and describe at least two ways that similarity between organisms can be

determined.

4. Compare and contrast a cladogram (branching tree diagram) with a pedigree (family tree).