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Introduction to Adaptation

Mary Jo Osborn



ABSTRACT

The purpose of this hands on, inquiry activity is to introduce the students to concepts used in evolution by making observations and comparisons of organisms. Students observe collections of specimens and discuss answers to open-ended questions in a cooperative learning format. Students learn about the concepts of common ancestry, homology, analogy, adaptive radiation, and evolution, while formulating creative answers based on their observations. This activity can be adapted for whatever specimens are available to the class. While this lab was designed for 10th grade introductory Biology students, it is easily adapted for use at any level in which the concepts are studied. It also gives you a way to use those specimens you inherited with your room and the "finds" the students drag in!

INFORMATION FOR THE TEACHER

MATERIALS

Each student group needs:
  • Textbook ( for checking definitions)
  • Notebook paper
  • Pen
  • The classroom is set up as 6 large tables (or push desks together), each containing a group of specimens and a list of questions for each table.

    Table 1: Bat wing, bird wing, large moth, and dragon fly.
    Table 2: Specimens of vertebrate hind feet, turtle, cat, human, frog, etc.
    Table 3: Skulls with beaks and taxidermied birds, owl, chicken, duck, pigeon, robin.
    Table 4: Hands, forelimbs of cat, human, frog, bat.
    Table 5: Skulls of human, dog, cat, sheep, rabbit.
    Table 6: Branches of assorted conifers.

    It is important to note here that the teacher should adapt the specimens to what is available. Some other specimens which could be used are exoskeletons, shells, lea ves, fruits, insect or leaf collections.

    TEACHING STRATEGY

    1. Have the tables set up with specimens and questions when the students enter the room. It generates curiosity if they see the specimens when they enter.

    2. Divide the class into groups of four or five. If the class is too small to have a group at each table, it is better to have empty tables than to have the groups too small to generate ideas.

    3. Student groups can be seated at any table and can progress to any table in any order as space opens up. Each group will have a person who acts as recorder to write the group's answers. The recorder will write the names of the students in the group at the top of a sheet of notebook paper and label each set of answers with the appropriate table number. As the group finishes one table, they move on to another.

    4. It is very important that the teacher allows the students to generate their own answers to the questions. A textbook is available to each group for checking definitions, but most of the answers rely on creative thinking and observations. If students are allowed to arrive at their own answers, they often think of things that the teacher might not anticipate.

    5. Depending on the size of the class and their rate of activity, the teacher may wish to set a time limit at each table and have all tables switch at the same time. I prefer to let the groups work at their own pace and handle stragglers individually.

    6. When all groups have completed all tables (usually one and a half class periods) students give class reports. Each group chooses a member to act as a reporter and the group is assigned to a table. The reporter describes the group's answers for their assigned table to the rest of the class. The reporter then leads a class discussion and calls on other students to add ideas. When each group has reported about their table, the answer sheets are passed in to the teacher.

    QUESTIONS FOR STUDENTS

    TABLE 1: FLIGHT STRUCTURES

    The structures on this table are all used for flight and are analogous.
    1. Define the term analogous.

    2. Which animals have an internal skeleton in their wings?

    3. Which animals seem most closely related?

    4. For each animal wing, list a feature which is characteristic of only that wing.

    5. Choose a wing. Explain the advantages of that wing over the others.

    TABLE 2: HIND FEET

    The structures on this table are hind feet and they are homologous.
    1. Define homologous .

    2. For each animal, list the main function that the hind foot serves.

    3. For each foot describe the special features that suit the form to its function.

    4. List three similarities and three differences between the skeleton of the frog foot and the human foot.

    TABLE 3: BEAKS

    The structures here are all bird beaks and exhibit adaptive radiation.
    1. Define adaptive radiation.

    2. For each bird, describe the structure of its beak.

    3. Relate the size and shape of each beak to the type of food each bird would eat.

    4. How do differences in beak structure limit competition for food among these birds?

    TABLE 4: FORELIMBS, HANDS

    1. Are these structures analogous or homologous? Explain your answer.

    2. Compare the skeletal structure of all four animals. List five similarities between the animals.

    3. For each animal describe the main function of the hand.

    4. For each hand, describe one feature that makes the hand well suited for its function.

    TABLE 5: SKULLS

    1. Are these structures analogous or homologous? Explain your answer.

    2. List five functions of a skull.

    3. List five ways these skulls differ.

    4. For each skull, list a special feature of the skull and explain how it relates to one of the functions listed in question 2.

    5. Identify the animals.

    TABLE 6: CONIFERS

    These plants belong to a group called conifers. They exhibit adaptive radiation.
    1. Describe five differences you see among the needles.

    2. How are these plants suited for low temperatures?

    3. Which plant can best withstand harsh winds?

    4. What is the advantage of long needles? Disadvantage?

    5. How are needles advantageous to broad leaves?

    SUMMARY

    Students have told me that the value of this activity lies in the fact that they were allowed to draw conclusions about relationships of organisms and adaptation by observation rather than being "lead" to specific examples. I find it valuable because students are required to look at organisms, evaluate the adaptive advantage of their features, and think in new ways.


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