A Phylogeny of Beasties
In this exercise, you will reconstruct the evolutionary history of a group of imaginary organisms known
as Beasties. The Beasties are a morphologically diverse group, and your analysis will take advantage of
this diversity. You will infer the most parsimonious (i.e., simplest) phylogenetic tree for the group of
Beasties depicted below. The outgroup taxon is indicated, as are six other Beastie taxa (A-F). Follow the
instructions and refer to the class discussions regarding the use of parsimony in reconstructing
phylogenetic trees.
You need to turn in the following:
 A list of characters used in reconstructing the phylogeny and the proposed character coding
(table 1)
 A complete taxon by character matrix (table 2)
 A tree depicting the most parsimonious estimate of evolutionary relationships for the Beasties
with the characters mapped onto the phylogeny
 The attached worksheet on phylogenetic basics
Page 1 of 4
1. Conduct a character analysis by examining the specimens above. How many characters can you
identify? Make a list of these characters, along with short descriptions of their various states.
Use 1’s and 0’s to indicate for the presence or absence of these characters, respectively.
Remember to code any character state in your outgroup as 0. Once you have these characters,
fill in Table 1.
2. On a scratch piece of paper, fill out a taxon by character matrix similar to the one on Table 2. By
convention characters are listed in columns and taxa in rows.
3. In preparation for determining the most parsimonious tree, organize your matrix in descending
order, starting with those ingroup taxa that are most similar (i.e., share the most character
states) with the outgroup. Enter this organized data into Table 2 – be sure you fill in the entire
table!
4. Use your notes from class as an example on how to reconstruct the phylogeny. The first step is
to identify a homologous trait that distinguishes members of the group of interest from the
outgroup (i.e., a synapomorphy).
5. Once you have determined the phylogeny, make a sketch into the space provided. Make sure
you map the characters onto the tree.
6. Finally, answer the questions regarding the beastie phylogeny.
Table 1. Characters used in the Beastie phylogenetic reconstruction
Character Name
e.g., Ears
0: absent
Coding scheme
1: present
Eye Size
0: small
1: big
Teeth
0: flat
1: sharp
Antenna
0: simple
1: branched
Fin
0: absent
1: present
Feet
0: round
1: pointed
Tail
0: looped
1: brushy
Spots
0: absent
1: present
Beard
0: absent
1: present
Tongue
0: absent
1: present
Page 2 of 4
Table 2. Taxon by character matrix
Characters
Eye Size
Teeth
Antenna
Fin
Feet
Tail
Spots
Beard
Tongue
Outgroup
0
0
0
0
0
0
0
0
0
E
1
0
0
0
0
0
0
0
1
D
1
1
0
0
0
0
1
0
0
B
1
1
0
0
0
0
1
1
0
F
1
1
1
1
0
0
0
0
0
A
1
1
1
1
0
1
0
0
0
C
1
1
1
1
1
1
0
0
0
Taxon
Figure 1. Beastie phylogeny (sketch your phylogenetic tree here).
outgroup
E
D
B
F
A
Beard
C
Pointed Feet
Brushy Tail
Spots
Branched Antenna
Tongue
Fin
Sharp Teeth
Big eyes
Page 3 of 4
Answer the following questions using your Beastie phylogeny:
1. For any monophyletic clade in your phylogeny, indicate the members of the clade and list a
synapomorphy that defines this relationship
(E,D,B,F,A,C): large eyes
(D,B,F,A,C): sharp teeth
(F,A,C): Fin; branched antenna
(D,B): spots
(A,C): brushy tail
2. List two autapomorphic traits and state to which taxon each of these belongs
Taxon B: beard
Taxon C: pointed feet
Taxon E: tongue
3. Based on your tree, circle all the groups in the list that are sister to each other:
C to D
A to C
E to B
(F,A,C )to (D,B)
E to (F,C, A)
E to (D, B, A, C, F)
C to (A,F)
Page 4 of 4