DO PANDAS REALLY EXIST? STUDENT HANDOUT
1. What question were scientists trying to answer?
2. Below are the three possible phylogenetic trees that scientists have proposed for the
raccoons, bears, and pandas. A phylogenetic tree shows how closely different species are
related to each other. The closer two branches are to each other on the tree, the more
closely the species are related to each other. For example, all three of these trees show that
the raccoon (Procyon lotor) is very closely related to the coatimundi (Nasua nasua), which
are both members of the raccoon family (procyonidae).
a. According to these phylogenetic trees, what other two species are closely related to
each other? _________________________________________
b. To which family do these two species belong? _____________________
c. According to the background information (in “Do Pandas Really Exist?”), fill in the option
numbers for each of the phylogenetic trees.
d. According to the background information on each of the proposed relationships, fill in the
“red panda” and the “giant panda” on the phylogenetic trees.
Option # _____
Option # _____
Procyon lotor
Procyon lotor
Nasua nasua
Nasua nasua
Option # _____
Procyon lotor
Nasua nasua
Ursus arctos
Ursus arctos
Ursus arctos
Ursus malayanus
Ursus malayanus
Ursus malayanus
3. Look at the biogeographical information that has been provided.
a. Which option (1, 2, or 3) does this information support? _____
b. Explain your answer.
4. Look at the fossil information that has been provided. If raccoons first appeared in North
America some 20 million years ago, and the red panda is a descendant of these original
raccoons, how could they have ended up in China? (Hint: look at the map that shows how
the continents have moved over time.)
5. Read the behavioral information that has been provided.
a. Which option (1, 2, or 3) does this information support? _____
b. Explain your answer.
6. Look at the information that has been provided about the size of the animals in Table 1.
a. Which option (1, 2, or 3) does this information support? _____
b. Explain your answer.
7. Table 1 includes the dental formulas for each species. A dental formula shows how many
of each type of tooth a species has on one half of the mouth (I = incisor, C = canine, P =
premolar, and M = molar). The number in the numerator is how many they have in the upper
jaw, and the number in the denominator is how many they have in the lower jaw. The
number after the “=” is the total number of teeth the animal has. For example, the in just the
left or right side of their mouth the raccoon (Procyon lotor) has 3 incisors in the upper and 3
in the lower jaw, 1 canine in the upper and 1 in the lower jaw, 4 premolars in the upper and
4 in the lower jaw, and 2 molars in the upper and 2 in the lower jaw. If you add all of these
up and multiply by 2, you will see that the raccoon has a total of 40 teeth.
a. Which option (1, 2, or 3) is supported by the dental formulas? _______
b. Explain your answer.
8. It is very difficult for a large animal like the giant panda to get enough calories from eating
bamboo shoots. Yet, they manage to do it with the help of their “thumb” (see Figures 11
and 12). Fill in the table below to explain how the giant panda ended up with this interesting
adaptation. Be sure to use the word “sesamoid bone” in your answer.
Steps to getting adaptation
The panda’s “thumb”
1.
2.
3.
4.
9. Now let’s summarize the conclusions you
have drawn so far.
a. Place a checkmark beneath the option
# that is best supported by the
evidence.
b. Add up the total number of
checkmarks in each column and write
them down as totals.
c. Based on your evidence so far, how
do you think the two
panda species are
related to the raccoon
and bear families?
Type of
evidence
Biogeography
Fossil Record
Behavior
Diet
Size
Dental Formula
Total =
Option
1
Option
2
Option
3
10. DNA Evidence. In the 1980s and 1990s scientists compared the DNA of various raccoons,
bears, and pandas. By looking at a particular sequence of nucleotide bases (A, T, C, and G)
they were able to compare their similarities and differences across species. The idea is that
the more similar the DNA sequences are to each other, the more closely related the species
are. Also, the more different the DNA sequences between species, the more distantly
related the species are. Below is a representation of what they found:
Species
Raccoon (Procyon lotor)
Coatimundi (Nasua
nasua)
Grizzly Bear (Ursus
arctos)
Sun Bear (Ursos
malayanus)
Red Panda (Ailurus
fulgens)
Giant Panda (Ailuropoda
melanoleuca)
DNA Sequence
A T A T A
A T A T A
A
C
A
A
A
G
T
T
A
A
A
A
G
G
A
A
T
T
A
A
C
C
C
C
A
A
C
C
G
G
C
T
G
T
A
C
C
A
T
A
C
C
A
T
A
C
C
C
C
C
C
A
G
T
A
C
C
A
T
A
C
C
A
T
A
C
C
C
C
C
C
A
G
T
A
C
C
A
A
T
A
T
A
T
A
C
C
A
C
G
C
A
G
T
A
C
C
A
T
A
C
C
A
T
A
C
C
A
C
G
Raccoon (Procyon lotor)
Coatimundi (Nasua nasua)
Grizzly Bear (Ursus arctos)
Sun Bear (Ursos malayanus)
Red Panda (Ailurus fulgens)
Giant Panda (Ailuropoda melanoleuca)
Giant Panda
Red Panda
Sun Bear
Grizzly Bear
Coatimundi
Raccoon
11. Look at the DNA sequences above (it is helpful if you have an extra copy that you can cut
out). Figure out how many nucleotide base differences there are between all of the
combination of different species and fill in the table below. Fill in the number of nucleotide
base differences between each pair of species.
-------------------
12. DNA evidence.
a. Which option (1, 2, or 3) does the DNA evidence support? ______
b. Explain your answer.
13. How did the DNA sequences become different from each other in the first place?
14. Like DNA, proteins can also be compared to determine relatedness.
a. Explain how you think scientists could compare proteins of different species.
15. What other information would have been helpful to you in this investigation?