Name ___________________________________________________________________________________ Per __________
CLADOGRAM ANALYSIS
What is a cladogram? It is a diagram that depicts evolutionary relationships among groups. It is based on PHYLOGENY, which is the study
of evolutionary relationships. Sometimes a cladogram is called a phylogenetic tree (though technically, there are minor differences
between the two). In the past, biologists would group organisms based solely on their physical appearance. Today, with the advances in
genetics and biochemistry, biologists can look more closely at individuals to discover their pattern of evolution, and group them accordingly
- this strategy is called EVOLUTIONARY CLASSIFICATION
CLADISTICS is form of analysis that looks at features of organisms that are considered "innovations", or newer features that serve some
kind of purpose. (Think about what the word "innovation" means in regular language.) These characteristics appear in later organisms but
not earlier ones and are called DERIVED CHARACTERS.
PART I - Analyze the Cladogram
Examine the sample cladogram, each letter on the diagram points to a derived character, or something different (or newer) than what was
seen in previous groups. Match the letter to its character. Note: this cladogram was created for simplicity and understanding, it does not
represent the established phylogeny for insects and their relatives.
1. ______ Wings
2. ______ 6 Legs
3. ______ Segmented Body
4. ______ Double set of wings
5. ______ Jumping Legs
6. ______ Crushing mouthparts
7. ______ Legs
8. ______ Curly Antennae
PART II - Create Your Own Cladogram
To make a cladogram, you must first look at the animals you are studying and establish characteristics that they share and ones that are
unique to each group. For the animals on the table, if the characteristic is present, place a (1) in the box. If the characteristic is not
present, place a (0) in the box. Based on that chart, create a cladogram like the one pictured above.
DRAWING OF YOUR CLADOGRAM:
Cells
Slug
Catfish
Frog
Tiger
Human
Backbone
Legs
Hair
Opposable
Thumbs
CLADOGRAM PRACTICE
Use this cladogram to answer the questions below.
birds
dinosaurs
crocodiles
turtles,
lizards,
snakes
mammals
11
10
9
amphibians
8
6
fish
5
7
4
3
2
??
Key:
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
vertebrate
tetrapod
amniotic egg
hair or fur
produces milk
warm blooded
scaly skin
parental care
bipedalism
asymmetrical feathers
warm-blooded (avian)
1
1. According to the cladogram, what characteristic do all of these organisms have in common? _______________________
2. Which of the following is NOT a characteristic of birds? ______
a. amniotic egg
b. scaly skin
c. hair or fur
d. parental care
e. tetrapod
3. What organism is the closest relative to birds? ___________________________________
4. What characteristic(s) do crocodiles and mammals share? ___________________________________________
5. What derived character distinguishes crocodiles from lizards? ____________________________________________
6. What characteristics are common only to mammals? ____________________________________________________
7. Which derived character(s) distinguishes birds and dinosaurs? _____________________________________________
8. What derived character(s) do fish and amphibians share? __________________________________________________
9. Who is more closely related… birds and crocodiles or birds and amphibians? Explain. ___________________________
_________________________________________________________________________________________________
10. What type of organism would fit best in the box with the question marks? Explain what trait it would have.
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