Bibliography

The paper by Singer et al. is one of two papers (the other is: Giese AR. 2005. Using inquiry and phylogeny to teach comparative morphology.The American Biology Teacher 67: 412 – 417.) whose methods we merged to create our own laboratory stream.  One goal of this work was to have students learn that phylogenetic trees are graphical representations of hypotheses about evolution.  The authors also point out that practicing phylogenetic analysis provides practice in critical thinking, strengthening students' logical and mathematical abilities, and their problem-posing and problem-solving skills.  Singer et al. provided skeletons of five animals (opossum, dog, cat, rat and rabbit) to their students, who were then asked to generate a character matrix based on observations of these skeletons.  Using this matrix, and other information on the anatomy, physiology, behavior and ecology of these animals, students were asked to propose a hypothesis of evolutionary relationship, using the extinct Megazostrodon as an outgroup (there are 105 possible hypotheses).  Students then tested this "tentative statement" using DNA sequence data to infer a phylogeny of these five animal group, showing the students that hypothesis are tentative statements that are open to testing and revision using additional data or data from a different source.  In our own work, we have used the opossum as outgroup, and then show the students that there are only 15 possible phylogenies.  Our students are given two of these 15 trees, and then asked to develop an explanation of why one is better than the other by mapping individual characters onto their trees and applying the principle of parsimony.