Why tax?

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Why tax?

				"Descriptive" zoology or the classification of animals is the foundation of zoology just as classification in general is the foundation of biological (and any) science. What is molecular biology but a classification of molecules and their functions? The functional equivalent at the organismal level is ecology. How good would organic chemists or molecular biologists be if they knew all about the kinds of reactions but nothing of the molecules themselves and their categories? It reminds me of the graduate student (in what was then a botany department dedicated mainly to cell biology and the characterization of lipids) who lost her research because she thought all spinach was the same. She took no account of the different varieties she was buying from the grocery store (there was, by some miracle, a plant taxonomist on her committee). What often passes as pure physiology or ecology is actually a pinnacle resting on a solid foundation of taxonomy and classification. How can we find what is new unless we are well acquainted with what is old? Witness the recent "rediscovery" of filament formation in Saccharomyces in Science. It seems to me that classification is the first activity of the human mind--as in the two taxa: mother and not mother. How can we count if we have no classification? How/Where does descriptive zoology "fit" into general biology? May I suggest that you start with kingdoms, symbiosis, and traditional notions of "protozoa" and see where it goes from there. Sorry to ramble so. Just a few crumbs as food for thought. Dave Williams ProfDHW@aol.com Science Division Anne Arundel Community College Arnold, MD 2101

				I agree that knowledge of diversity is important. Learning names and characteristics of taxonomic groups is also important. The question is, in what conceptual framework will this material be presented? A classic approach would be to take each group, describe it, draw some specimens, and memorize the info. My personal opinion is that, while this may be useful, it makes the least use of the information. A more "modern", functional approach would be to think about taxonomy in terms of, say, design. In our introductory biology course, for example, students learn the major invertebrate phyla within the framework of "solutions to design problems" (mechanical support, transport, reproduction, etc.). I'm sure many others use this approach also. In addition, we address general issues of taxonomy and systematics in the laboratory by giving the students a set of live echinoderms (everything but crinoids) and asking them to describe the animals, choose dichotomous characters that they can enter into the program MacClade, and construct phylogenetic trees using the program. They do this without first knowing much about the animals themselves, so that they have to confront issues like "what's a taxonomically reliable character?" The general point is that students will forget the specifics. The lasting thing we can do for our students is to teach them ways of looking at the world and to give them models for assimilating new information once they have left the classroom. But you probably all know that already. Sara Hiebert Biology Department Swarthmore College Swarthmore, PA 19081 610-328-8053

				This is exactly the approach we use here, except that we give different collections of "crittters" to each lab group and they present their phylogenic tree and choice of taxonomic characters to the rest of the lab. This works well and I can recommend MacClade as a great piece of software. Graham R. Kent Dept. of Biology Smith College Northampton, MA 01063

				I agree completely--in fact I have a personal fascination with knowing the names of organisms, being able to identify them, and being able to recite the characteristics of the taxa into which they fall. I also think that simply sitting down and drawing a specimen is a wonderful laboratory exercise in itself. I just wouldn't want to do all of that in the absence of a broader conceptual framework that conceives of organisms as solutions (in fascinating variety!) to common design problems. As for the use of McClade, Graham Kent has pointed out another of the many possible ways in which this tool can be used to good effect. By having each group work on a different set of organisms, each group has to forge its own way. By having each group work on the same organisms, you can teach other concepts: 1) The characters you choose influence the form of the tree 2) It is possible to get identical trees from different sets of characters, and identical trees with different treelengths 3) Absolute treelengths are difficult to compare if different sets of characters are used 4) Using the same characters may result in different trees of equal lengths. How do we decide which one is the "better" tree? This is all a little disconcerting for freshmen, since they of course want to know the "right" answer at the end of the lab. To answer this question, we show them 5 different recently published trees to demonstrate that systematics is a living, breathing field in which people continue to invest intellectual energy (sometimes they even throw food, or stand up on chairs and yell at each other). Sara Hiebert Biology Department Swarthmore College Swarthmore, PA 19081 610-328-8053