Some of the students are natural "lumpers" and some are natural "splitters." If you approach this chapter with the belief that there is room for both the lumpers and the splitters in the biological world, you can have a very successful experience with this material.
The opening vignette contains both good information and good controversy about taxonomy.
In many ways this is a chapter with more questions than it has answers. Use that to your advantage to show the exciting and challenging frontiers of modern biology. Taxonomic absolutes should not be an objective for your course.
You might wish to copy and distribute to your students the Overview of Chapter Objectives flowchart found at the beginning of this Instructor's Manual Chapter.
** Here is an interesting way to introduce taxonomy to your students, particularly if your course does not include a lab on classification.
Bring into your lecture hall a number of assorted objects such as a pen, pencil, twig, button, coffee cup, paper bag, paper clip, leaf, scissors, etc., etc. Ask the class to write down a grouping scheme for these objects. After a few minutes, state that most people will put the pen and pencil together because they are both writing objects. But, why not put the pencil and the twig together because both are wood? Again, many people would put the coffee cup and the paper bag together because they both hold things. But, why not put the button and the coffee cup together because they are both round? You can keep on going depending on the objects you have brought in.
The whole purpose of the above exercise is to show the students the intricacies of classification.
** Another interesting idea as you begin this section is to ask your class to write down (not to hand in) spontaneous definitions of "Plant", "Animal", and "Fungus." Then ask for volunteers to share their definitions. You will be amazed at the misconceptions.
- I. Think of our need to name people. If someone helps someone else anonymously, the question is always, "Who was that?" We, as humans, are great identifiers; we always want to name and to classify. This is true whether we are lumpers or splitters.
The second paragraph of this section uses the phrase "increasingly restrictive." This is a good phrase but students often confuse the phrases "increasingly restrictive" and "increasingly general." For some reason, they think of species as the most general term, instead of the most specific or restrictive.
At the top of page 427 is a statement about the more taxonomic levels two organisms have in common, the more recently they diverged from a common ancestor. Use a simple cladogram or phylogenetic tree to explain this sentence.
Refer to the Chapter 1 notes on taxonomy.
- II. The last part of this section discusses the uses of taxonomy for ecological predictions. You might ask the class if this is valid.
- IV.A. Aristotle's kingdom concept (in simplified form) looked something like this.
This is basically a two kingdom system with humans at the top.
The naming of all organisms using a Latinized system to designate genus and species is termed the binomial system of nomenclature. The ultimate in Latinizing is the name Carolus Linnaeus. The Swedish botanist, Karl von Linne (1707 - 1778), changed his name to Carolus Linnaeus to match his own identification system.
You may have some students who learned only the two kingdom system (even though it has been over 130 years since Haeckel devised the three kingdom system). Some school districts do not recognize more than two kingdoms so this will be a shock to any students who have not heard of the more complicated kingdom systems.
- IV.B. The question is raised about where taxonomists should place the archaea. One problem you might throw out to your students is how to define Monera. If the Monera are simply prokaryotic and unicellular, then maybe the archaea belong with them. But is the real definition of Monera more restrictive? Obviously the question hasn't been answered yet. You can get around this by accepting the three domains as an evolving concept and using the five kingdoms as a matter of convenience. Figure 21.4 is an excellent diagram for showing possible "inter-kingdom" relationships.
- IV.C. Again you are faced with the concept of "more restrictive." It is common sense, but some will still want to turn it around.
- IV.D. Consider making a short chart showing how mutualism, commensalism, and parasitism are all subdivisions of symbiosis. Bring in any other "-isms" you may think of.
- V.A. Diagram a method or two for estimating biodiversity. Ask whether or not the class considers these methods valid indicators of the numbers of species (or individuals) present.
