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. ______ Cerci (abdomenal appendages)
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, indicate whether the characteristic is present or not. Based on that chart, create a
cladogram like the one pictured above.
Cells
Backbone
Legs
Slug
Catfish
Frog
Tiger
Human
DRAWING OF YOUR CLADOGRAM
Hair
Opposable Thumbs
Constructing a Cladogram
Objective: Students will construct a cladogram using descriptions and information about 7
imaginary animals. Students will determine which traits are derived traits, and identify
synapomorphy and automorphy of characteristics.
Tips for constructing your cladogram
1. Use the times to determine the positioning of the species. Older organisms will appear first on
the cladogram
2. Determine features that are shared among organisms - these are synapomorphies - Place an S
on these features to help you keep track
3. Determine features that are unique to organisms - these are automorphies - Place an A on these
features
4. There may be several ways to represent this cladogram, remember that cladistics and
systematics is inexact, do not worry if yours looks different from others.
Description of Species
Species 1 - Fossils of this species date back to
30,000 years ago. The organism has a single
antenna that is branched (like a Y). It has two
eyes positioned on top of the head a non
segmented body
Species 2 - Fossils of this species date back to
8,000 years ago. This organism has branched
antennae, 3 body segments, the middle segment
has fleshy appendages with a bendable joint.
Species 3 - Fossils of this species date back to
25,000 years ago. The organism has a branched
antenna (like a Y), body is divided into 2
segments, and eyes positioned on the top of the
head. In addition, the last segment of the body
has a long curley tail.
Picture
Species 4 - Fossils of this species date back to
10,000 years ago. This organism has branched
antennae, 2 body segments, eyes positioned on
the top of the head, fleshy appendages on the last
segment have a bendable joint.
Species 5 - Fossils of this species date back to
50,000 years ago. The organism has a single
antennae, two eyes positioned on top of a head
and a non segmented body.
Species 6 - Fossils of this species date back to
20,000 years ago. This organism has branched
antennae, 2 body segments, eyes positioned on
the top of the head, and small flesh appendages
on the last segment. This organism also has a
ridge of spines on the last segment.
Species 7 - Fossils of this species date back to
31,000 years ago. The organism has a single
branched antennae (like a Y) and a club like
structure at the end of the branches of the
antennae. It has two eyes positioned on top of the
head and a non segmented body.