Student Exploration: Cladograms
Vocabulary: adaptation, amino acid, amnion, artiodactyla, bipedal, clade, cladistics, cladogram, convergent evolution, evolution, flower, mammary glands, molecular, morphological, multicellular, parsimony, sagittal crest, phloem, selenodont teeth, SNP, xylem
Prior Knowledge Questions (Do these BEFORE using the Gizmo.)
Look at the images below. Which two organisms do you think are most closely related?
Worm Deer Turtle
Why do you think so?
Cladistics is a method of hypothesizing the evolutionary relationships between species. A cladogram is a branching diagram that illustrates these relationships. For example, the cladogram on the right shows that deer are more closely related to turtles than to worms. In the Cladograms Gizmo, you will use morphological(physical characteristics) and molecular data to create cladograms.
To begin, make sure Plants is selected for the Organism group and Morphological is selected for the Data type. Click on one of the characteristics to the left of the table on the TABLE tab. Information about the characteristic will be shown on the ORGANISM tab.
Using the information on the ORGANISM tab, describe each of the characteristics below.
Xylem and phloem:
Get the Gizmo ready:
Check that Plants and Morphological are still selected for the group and data type.
Question: How do you build a simple cladogram based on physical characteristics?
Fill in: Using what you learned in the warm-up, fill in the table. Clicking one of the boxes of the table will add a check mark to indicate the presence of a characteristic. Then, select Check table and adjust any of the boxes you may have filled in incorrectly.
Which organism has the fewest shared characteristics?
Organize: Now you are ready to organize the table.
How many characteristics (check marks) does each organism have?