Life Science Ursinologist _______________________ Cladogram Activity A cladogram is a diagram based upon similar traits found in organisms. Cladograms show evolutionary relationships among groups of organisms. Scientists use the fossil record, structural comparisons, and molecular comparisons (proteins, DNA, and RNA) to construct cladograms. Organisms that are located in close proximity to one another on a cladogram share similar evolutionary characteristics and are, therefore, more closely related. That is, they share a more recent common ancestor. 1. Which organisms are most closely related? a. 5 & 6 or b. 6 & 7 2. Which organism is the common ancestor for 6, 7, & 8? ___________________________ 3. What is the common ancestor for all organisms in this cladogram? __________________ 4. Underline the conclusion that best supports the data given in this cladogram: a. The short-faced bear (4) was the ancestor of the black bear. b. Present day bear species are more closely related than their ancestors were. c. Modern bears evolved from species that are now extinct. d. Natural selection favored the brown bear over the American black bear. 5a. You are a scientist that has discovered an extinct member of the bear family that is most closely related to the American Black Bear (7). Add this organism to the cladogram, using an “X” to show the placement of the bear. 5b. Give the bear you discovered a name, both common and scientific. Common name:
Scientific name: 6. DRAW Ursus minimus (3) the extinct ancestor of modern bears. What characteristics do you think this organism would have? Drawing: Characteristics: ______________________________________
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______________________________________ 7. Build your own cladogram using the following shapes. Hint: try to group the shapes into similar categories then build your cladogram. Use a straight line as the common ancestor. Have fun and be creative! ☺ Triangle Hexagon Trapezoid Parallelogram Square Pentagon Rectangle Rounded Rectangle Octagon Oval Donut Circle