Now that we have separated the dog and bear from the cat, it is time to separate them from each other.This problem solving activity teaches students how to build a cladogram and reinforces the important concepts of cladograms and cladistics to your biology or life science students in grades I use this activity when teaching my unit on classification and taxonomy, but it would also be appropriate to use during your lessons on evolution and natural selection. Let's separate the bear and dog from the cat by using enhanced sense of smell as a derived characteristic. What makes the organisms in your ingroup different from each other? Now that we have included the bear, dog, and cat in our ingroup, we can begin choosing derived characters to separate them. Doing this makes the rabbit our outgroup. In our example, we could use consumption of meat to separate our bear, dog, and cat from our rabbit. Think of traits that are physical or physiological in nature that are unique to that order or family of organisms. What makes your organisms different from each other?
For example, if you chose a dog, a cat, a bear, and a rabbit, your ancestral trait, the trait they all share, could possibly be hair, or warm-bloodedness endothermy. It also serves as a point of comparison between the them. What do all of the organisms you chose have in common? The purpose of the ancestral characteristic is to link the animal in the outgroup to the other animals. The exception to this could be the organism in the outgroup, as the outgroup is meant to be used as a point of comparison against the other organisms. Make sure that they are within the same order or family.
Pick four to six organisms to be in your cladogram. Did you use this instructable in your classroom?Īdd a Teacher Note to share how you incorporated it into your lesson. Having the skills to construct a cladogram will help your understanding of evolutionary relationships. This instructable will show you step by step how to make one, and how to avoid confusing derived traits with ancestral ones. Nearly every biology student has heard of cladistics and cladograms, however, cladograms can be difficult to construct.
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