Adapt an Iguana

(Download the MS Word version of this document.)

Purpose

To determine what traits are necessary for survival in particular environments; to explain how traits evolve.

Materials

• colored pencils
• paper and pen
• unlined paper

Background Information

When Charles Darwin visited the Galopagos Islands, he observed many kinds of animals. In addition to finches and land tortoises, he took extensive notes on the indigenous (native) iguanas. One type lives along the shore and eats seaweeds. Another type lives in forests and fields away from the shore. It feeds on leaves, berries, and cactus plants. Yet another is the world's only marine lizard species. It lives in colonies on the lava shores and swims offshore to feed. All types evolved from the same ancestor. The ancestral lizard may have looked like the South American iguana pictured on the next page.

Procedure

1. Working with a partner, trace the ancestral lizard lightly in pencil on the unlined paper. Your group will be assigned one of the following environments: deciduous forest, rainforest canopy, tundra (alpine or Arctic), African savanna, desert, river ecosystem, lake ecosystem, coniferous forest, coral reef, intertidal zone (including tidal pools), estuary or abyssal zone. Identify its habitat on your sketch as a subtitle.
2. Change the traits of the lizard you have traced to show how it has evolved to survive in its new habitat. Make at least three physical changes to its anatomy.
3. Think of at least three behavioral changes that the lizard must make in order to survive in its new environment.
4. Give your iguana at new common name and use this for the title of your sketch.

Questions

Copy the lab title and purpose on a separate sheet of paper. Answer the following questions using complete sentences. Do not use the words "it" or "they" or any other pronoun in your answer (unless it has already been identified in your answer). When you have finished answering the questions, staple them on top of your iguana sketch.

1. List the three physical adaptations to its environment and explain how each helps it to survive.

2. Describe how you think these adaptations must have evolved.

3. List the three behavioral adaptations to its environment and explain how each helps it to survive.

4. Explain the following statement: "Organisms do not adapt in order to survive. Organisms survive because they are already adapted."