Cladogram Activity – Classifying Fruits
Name: ______________________ Class:___
Content and Process Unit Targets
IV. I will use evidence from embryology, anatomy (homologous structures & vestigial structures),
molecular biology, paleontology, and physiology to support the theory of evolution by natural
selection and classification by common ancestry (descent with modification).
C. Evaluate evidence provided by a data set in conjunction with a cladogram to determine evolutionary
history and speciation and or draw a cladogram given shared & derived characters.
Complete the sentences below as you watch the animation about how to construct a cladogram.:
http://ccl.northwestern.edu/simevolution/obonu/cladograms/Open-This-File.swf
1. The first step for constructing a cladogram is to choose a set of _o__________________.
2. Observe the organisms and list how the organisms are _d_________________ and how they are
_a__________________.
3. Construct a table to the list the character _s________________ of each organism.
4. Sort organisms into _b___________ using information from data table.
5. The sorting processes generates a __V____________ _d_______________ which is used to
build a _c______________.
Now, it’s YOUR turn to make a cladogram of the five different types of fruit specimens.
1. Complete the data table below as you make observations about the different fruits:
Derived character
CANTALOUPE
CUCUMBER
APPLE
PEACH
ACORN
(Mark X if character is present)
Is a fruit
Is a fleshy fruit (lacks a shell)
Has many small seeds
Is a large-sized fruit
2. Complete the Venn Diagram below using the evidence in your data table:
3. Use the Venn Diagram to make your cladogram. Label derived characters (dots) and fruit type (box).
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Cladograms, Clades, and Characters:
Adapted from Campbell Biology 8th edition, AP edition pages 538 – 548
The evolutionary history of organisms can be represented in a branching diagram called a
phylogenetic tree or cladogram. Dichotomies or two-way branching points represent the evolutionary
relationships between organisms. Each branch point represents divergence from a common ancestor.
Examine the cladogram in Figure 1 below. Branch point (node) #1 represents the common
ancestor to taxa A, B, and C. Node #2 represents the common ancestor for all organisms in taxa A – F
shown on the cladogram. Therefore, the cladogram, read from left to right, indicates passage of time with
modern, extant organisms listed on the far right side. Node #4 is a more recent common ancestor between
taxa B & C compared to the common ancestor indicated at node #1. Please understand that taxon C did
not evolve from taxon B or vice versa. Node #4 implies that taxa B & C share a common ancestor. Node
#3 does not follow the dichotomous nature of a cladogram because three taxa diverge from this node.
Therefore, the evolutionary relationships between taxa D, E, and F has not been determined.
Figure 1
Evolutionary relationships are inferred from morphological and molecular evidence. Homologies
are similar structures in related organisms due to shared ancestry. A common morphological homology is
the similar pattern of bones in the forelimbs of mammals including humans, whales, dogs, and bats. Be
careful to not confuse homologous similarities caused by divergent evolution with analogous similarities
due to similar selection pressure (convergent evolution). An example of an analogy is the hydrodynamic
shape of a penguin and a shark. Both organisms hunt their prey in water and a streamlined body shape
allows them to move through the water efficiently. The water environment over time selected for both
sharks and penguins with an efficient swimming body shape. However, sharks and penguins DO NOT
share a recent common ancestor. Their morphological similarity is due to a environmental selection
pressure and not decent from a common ancestor.
The more similar the DNA base sequences between two organisms, the more recently these
organisms share a common evolutionary ancestor. We’ll discuss molecular homologies in a later activity.
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Homologies are used to infer evolutionary relationships. Phylogentic trees called cladograms use
homologies to illustrate these evolutionary relationships. Biologists place organisms into clades that
include an ancestral species and all of its descendants. The phylogenetic tree on the previous page used the
term taxon and here you’re introduced to the term clade. What’s the difference? A taxon is a general term
used to describe an organism’s unit of classification such as phylum, order, or family. A clade is a group
of species and their common ancestor. The terms clade and taxon can be used as synonyms if the taxon is
monophyletic. Examine Figure 2 and its descriptions.
Figure 2
Group I is considered a monophyletic group (clade). Group I is composed of organisms A, B, C,
and their common ancestor.
Group II is a paraphyletic group. Group II is composed of organisms D, E, F and their common
ancestor. However, since organism G is not included within the group, Group II is not monophyletic.
Group III is a polyphyletic group. Group III is composed of organisms that have different
common ancestors. Node #1 is the common ancestor for organism C (and A & B). Organisms D, E, F, G,
have node #2 as their common ancestor. Therefore, multiple phylogenetic groups are included within this
grouping.
Homologies help biologists begin to construct cladograms and infer evolutionary relationships.
Organisms both share characteristics with their ancestor and differ from their ancestor. All members of a
cladogram have characters in common due to their divergence from a common ancestor. Shared
ancestral characters (plesiomorphy) are those that originated in the ancestral species of a clade. Shared
derived characters (apomorphy) distinguish how later species diverged to differ from their ancestral
species and related taxa. A character table is useful to begin to infer evolutionary relationships between
organisms. See the character table and resulting cladogram in Figure 3.
Figure 3
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Use the phylogenies and questions on the attached pages to evaluate your understanding for how to
construct and interpret cladograms.
Examine the cladogram below:
• Shade, USING GREEN COLORED PENCIL, the two organisms that belong to a clade that does
not include the third organism. Shade, USING RED COLORED PENCIL, the organism that does
not belong to the clade.
• Circle the point on the cladogram that shows the most recent common ancestor of the crab and the
barnacle.
• Mark an X on the point on the cladogram that shows the most recent common ancestor of mollusks
and crustaceans.
• Draw a box around the characteristic that all three organisms have in common.
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Use the figure to answer the questions below.
1. According to the figure, which species is most closely related to red pandas?
2. Although giant pandas and raccoons share some distinct anatomical similarities, they are in different clades.
What type of evidence do you think was used !"!!
to #construct
this diagram?
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3. Biologists had previously classified giant pandas together with raccoons and red pandas. What did DNA
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4. _____Which of the following is the
! closest extinct
relative of species C and D?
a. A
b. B
c. C
d. D
5. _____Which of the following is the closest living
relative of species C and D?
a. A
b. B
c. E
d. 2
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The diagram below shows the relationship between four types of plants. Use the diagram to answer
questions the questions
6. _____ Which derived character is shared by pine trees and flowering plants but not ferns?
a. flowers
b. mosses
c. vascular tissue
d. seeds
7. _____ Which of the following pairs of plant groups share the most recent common ancestor?
a. ferns and pine trees
b. mosses and ferns
c. pine trees and flowering plants
d. mosses and flowering plants
8. _____What is the name of the domain that contains all of the organisms shown in the diagram?
a. Eubacteria
b. Archaebacteria
c. Algae
d. Eukarya
9. _____Which group of plants evolved first (is the oldest)?
a. Mosses
b. Ferns
c. Pines
d. Flowering plants
_____What derived character is exclusive to flowering plants?
a. vascular tissue
b. flowers
c. mosses
d. seeds
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Look at the diagram below of a proposed evolutionary tree to answer questions.
10. _____The seven modern groups of animals evolved from what common ancestor?
a. Therapsids
c. Diapsids
b. Cotylosaurs
d. Dinosaurs
11._____This diagram suggests that crocodiles and birds evolved from
a. Tuatara
c. Therapsids
b. Thecodonts
d. Archaeopteryx
12._____ Of the five major groups that evolved from cotylosaurs, which two groups have no living
descendants?
a. Pelycosaurs and Diapsids
c. Diapsids and Turtles
b. Ichthyosaurs and Plesiosaurs
d. Ichthyosaurs and Pelycosaurs
13. _____Of the five major groups that evolved from cotylosaurs, which has shown the least evolutionary
change in its living representatives today?
a. Turtles
c. Ichthyosaurs
b. Diapsids
d. Pelycosaurs
14. _____According to this diagram, which group listed below is the most closely related to the birds?
a. mammals
c. lizards
b. turtles
d. dinosaurs
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Use the cladogram to answer the questions #15-17 below:
15. What five probable ancestors of the modern bird (robin) are shown on the cladogram?
16. Which dinosaur is probably the most recent common ancestor of Velociraptor and Archaeopteryx?
17. Which traits shown on the cladogram are shared by Archaeopteryx and modern birds?
Use the cladogram to answer the questions 18-21 below:
18. Which node occurred earliest in time?
19. Which node represents the most recent common ancestor of terminal taxa B and C?
20. Which node represents the most recent common ancestor of terminal taxa A and B?
21. Which species are extant (currently living on Earth)?
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22. Of the cladograms shown below, which one shows a different evolutionary history from the others?
Identify the shaded groups as: monophyletic,
paraphyletic, or polyphyletic
23.
24.
25.
26.
27.
28.
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