Exercise 2 - Thinking About Classification and
Individuals
Sometimes it is difficult to know whether you are looking at a
species of plant or animal as it typically exists, as it has been
deformed in some way, or as it exists in only one stage of its
life. Some small change may be indicative of a new species, or it
may merely be a blemish or temporary condition. In this exercise
you will think about these possibilities using the figures shown
above and the three slides entitled "All Individuals Within a
Species Are Not Alike," located on page
18.
Questions
1. Suppose that when you first see shape 28 it looks like the
shape in Figure 2. The next day you come to class and shape 28 now
looks like 28b in Figure 3. The shape is the same size, but the
upper appendage is missing. List some possibilities for explaining
the missing appendage.
2. After few weeks figure 28b loses its lower appendage and the
shape looks like 28c in Figure 4. What might explain this new
change? Can you eliminate any of the possibilities you listed in
Question 1, above?
3. A few weeks after changing to 28c, the shape dies. What, if
anything, can you conclude from this?
4. One day you are out in the woods and you see a group of
shapes. You pick up a sample and take it back to your laboratory.
You find that you have about equal numbers of shapes 28, 28b, and
28c. Of the many reasons that explain individual variation, which
ones probably don’t apply to the shapes you found? Be sure to
explain why they probably don’t apply.
5. Having found equal numbers of shapes 28, 28b and 28c, come
up with a hypothesis that might explain the variation. How would
you design an experiment to test your hypothesis?
6. During spring break you travel to South America. You find
some shapes and take them to a laboratory. Out of the 20 shapes
you took, 18 look like shape 28b, one looks like 28c and one looks
like 28. What might explain the variations seen in shapes 28 and
28c?
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