"Caminalcules" are a group of imaginary animals first created by evolutionary biologist Joseph H. Camin at the University of Kansas. A combination of his last name of "Camin" and "animalcules", Caminmalcules are drawings of animal-like creatures that have been used in evolution education to teach various subjects, including how to make phylogenetic trees. In this lab, students will determine the evolutionary history of the Caminalcules using "fossils" and other evidence such as convergent evolution and vestigial structures.
Not only does the taxonomy of a species need to be descriptive of the traits the species has, it also needs to reflect the evolutionary history of that species. This type of classification can be as broad as Phylum Chordata for all vertebrate species or as specific as Genus Panthera for large cats. These categories reflect the evolutionary history of species through their descent with modification from a common ancestor. The more taxonomic categories two species have in common, the more recently they diverged from their common ancestor. This means that large cats in Genus Panthera are much more closely related than species that only have Phylum Chordata in common.
One way evolutionary relationships between organisms can be graphically shown is in the form of a phylogenetic tree. The fossil record, along with similarities in DNA and other anatomical evidence can give clues as to how recently species diverged from their common ancestors. Phylogenetic trees consist of branching lines that diverge as species diverge relative to the common ancestor.
Constructing Phylogenetic Trees for Caminalcules
- Get a large sheet of paper or poster board to draw the Caminalcule phylogenetic tree.
- Use a meter stick to draw 20 equally spaced horizontal lines on the paper. Each line represents a time span of one million years.
- Label each line so that the one at the bottom of the paper represents an age of 19 million years and the top line represents the present (0 years).
- Print and cut out all the Caminalcules in the pictures on this page (including the living species). Put them in piles according to their age (the number in parentheses).
- Beginning with the oldest fossils, arrange the Caminalcules according to their evolutionary relationship.
- Use a pencil to draw lines at first to indicate the path of evolution. Don't darken the lines or glue down the Caminmalcules until the path is certain to be correct.
- Branching should involve only two lines at a time. That means there should not be three or more lines touching at any one point.
- Some living forms are also found in the fossil record. Identifying these can help figure out when others diverged.
- Just like with real life species, there are gaps in the fossil record for some lineages of Caminalcules. Also, keep in mind that some species went extinct and do not have branches off of them.
- The Caminalcules numbering is random. The numbers do not give hints to evolutionary relationships.
- There is only one correct phylogenetic tree possible. Joseph Camin purposefully made his imaginary animals this way. He started with the most primitive form (#73) and gradually modified it using a process that mimics evolution in real organisms.
- Some lineages (for example, the descendants of species 56) branched many times and have many living species. Describe some of the ecological conditions that may have contributed to the rapid branching of some lineages.
- Some lineages (for example, the descendants of species 58) changed very little over time. Why do you think this is? Give some ecological conditions that may keep some lineages stable and unchanging.
- Some Caminalcules went extinct without leaving additional lines. What are some factors that might increase or decrease the probability of a species going extinct?
- Find two examples of convergent evolution among the Caminalcules. What are some reasons convergent evolution of these lines may have occurred?
- Describe two examples of vestigial structures that you can find among the Caminalcules and why these structures may no longer be useful.