How to Make a
Cladogram
(Adapted from ENSI/SENSI lesson plan: Making Cladograms
http://www.indiana.edu/~ensiweb/home.html)
Cladograms are diagrams which depict the relationships between different groups of taxa called “clades”.
By depicting these relationships, cladograms reconstruct the evolutionary history (phylogeny) of the taxa.
Cladograms can also be called “phylogenies” or “trees”.
Cladograms are constructed by grouping organisms together based on their shared derived
characteristics.
Example:
1. Given these characters and taxa:
Taxa
Characters
Vertebrae
Two pairs of
limbs
Mammary glands
Shark
X
Bullfrog
X
X
Kangaroo
X
X
Human
X
X
X
X
Placenta
X
Sponge
Jellyfish
Flatworm
Earthworm
Snail
Fruitfly
Starfish
Human
2. Characters
Draw a Venn diagram. Start with the character that is shared by all the taxa on the outside. Inside each
box,
write
the taxa that
Cells
with
X have only
X that set ofXcharacters. X
X
X
X
X
flagella
Symmetry
X
X
X
X
X
X
X
Bilateral
X
X
X
X
(X)
X
symmetry
Mesoderm
X
X
X
X
X
Head
X
X
X
develops
first
Anus
X
X
develops
first
Segmented
X like so:
X
3. Convert the Venn diagram into a cladogram
body
Calcified
X
Shell
Chitonous
X
Exoskeleton
WaterX
vascular
system
Vertebrae
X
Name:
Construct a Cladogram
Convert the following data table into a Venn diagram, and then into a cladogram:
Characters
Shark
Bullfrog
Kangaroo
Vertebrae
X
X
X
Two pairs of
X
X
limbs
Mammary glands
X
Placenta
Characters
Cells with
flagella
Symmetry
Bilateral
symmetry
Mesoderm
Head
develops
first
Anus
develops
first
Segmented
body
Calcified
Shell
Chitonous
Exoskeleton
Watervascular
system
Vertebrae
Human
X
X
X
X
Sponge
Jellyfish
Flatworm
Earthworm
Snail
Fruitfly
Starfish
Human
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
(X)
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Understanding phylogenies - Cladograms
Understanding a phylogeny is a lot like reading a family tree. The root of the tree represents the ancestral lineage, and the tips of
the branches represent the descendents of that ancestor. As you move from the root to the tips, you are moving forward in time.
When a lineage splits (speciation), it is represented as branching on a phylogeny. When a speciation event occurs, a single
ancestral lineage gives rise to two or more daughter lineages.
Phylogenies trace patterns of shared ancestry between lineages. Each lineage has a part of its history that is unique to it alone
and parts that are shared with other lineages.
Similarly, each lineage has ancestors that are unique to that lineage and ancestors that are shared with other lineages — common
ancestors.
Venn Diagram (Draw your cladogram on the back):
Misconceptions about humans
The points described above cause the most problems when it comes to human evolution. It is
important to remember that:
1. Humans did not evolve from chimpanzees. Humans and chimpanzees are evolutionary cousins
and share a recent common ancestor that was neither chimpanzee nor human.
2. Humans are not "higher" or "more evolved" than other living lineages. Since our lineages split,
humans and chimpanzees have each evolved traits unique to our own lineages.