The Caminalcules

(Image from Robert P. Gendron's Evolution of Caminacules web site).

Summary

This exercise introduces the problem of classification, relationship, character coding, and parsimony. It is intended partly as fun, partly to get you thinking about some basic issues in phylogenetic analysis. In the next session you will analyse relationships among the Caminalcules using computer programs, but first we will get familar with the creatures and speculate on their phylogeny.

Aims

After this exercise you should

• understand that there are many possible classifications
• be thinking about characters and how they relate to classifications
• have a good grasp of parsimony

The Caminalcules

The Caminalcules are artificial animals created by the late Professor Joseph Camin of the University of Kansas as part of a study of how taxonomists classify real organisms. Sokal (1983) describes the complete set of Caminalcules, then spent much time seeing whether existing methods of phylogenetic nference could reconstruct the "actual" tree for the group, which Camin made up as he developed the Caminalcules. In this practical we will use the Caminalcules to explore the problem of classification, with emphasis on using the principle of parsimony to find the best tree.

Related sites

Caminalcules, Snouters and Other Unusual Creatures

View the Caminacule movie created by Robert P. Gendron (AVI format, 3.9 Mb)

The "recent" Caminacules...

Creating a classification

You have all 29 "recent" Caminalcules on individual cardboard cut-outs.

To do: Produce a classification of the Caminalcules.

This may take any form you desire, but be prepared to explain why you chose the kind of classification you did, and how you produced it. Draw your classification here:

Q: What does your classification represent?

Q. If two Caminalcules are related in your classification, or appear close together, what does that mean?

Creating a data matrix

In order to be rigorous we need to be explicit about what information we use to construct our classifications.

Q: What is a character? What is a character state?

To do: 1. List some characters and their states for the Caminalcules:

2. Now, score each Caminalcule for each character and enter in this matrix. Give each character state a number (e.g., absence = 0, presence = 1).

                        Caminalcule
                    1 11111 11112 22222 2222
Character 12345 67890 12345 67890 12345 6789
---------------------------------------------
1
2
3
 

Q: Some characters may occur only in some Caminalcules. How would you code these characters in your matrix?

As an example, think of the character "fusion of eyes". Divide the Caminalcules into two piles, those with fused eyes and those without fused eyes. What will you do with the eyeless Caminalcules?

Finding the most parsimonious tree by hand

Given this data matrix, what do you think is the cladogram for the Caminicules? Caminalcule 23 is the outgroup.