Laboratory Activity #01–The Beaks of Finches

Part A. Student Laboratory Packet
Introduction
Environmental conditions act as selecting agents because they select organisms with the most beneficial traits to become the parents of the next generation. Within a species, individuals with variations that make them better adapted to their environment will survive and reproduce in greater numbers than those without such adaptations. Observations have shown that the offspring of better-adapted individuals inherit many of their parents’ favorable variations.
Finches are small birds found in many locations throughout the world. Charles Darwin used the numerous finch species found on the Galapagos Islands as evidence of natural selection. The great variety of beak adaptations present on the Galapagos is thought to be due to the isolation of bird populations on the islands with different kinds and amounts, of food. Seed-eating finches exhibit a great number of differences in beak shapes and sizes. During ongoing competition for resources. some finches are successful and become more numerous, while less successful finches decrease in number.
In this laboratory activity, you will work with different tools that will serve to model finch “beaks.” The seeds provided represent finch food on a particular island. You will compete with other “finch” species to see which “beak” is best adapted for obtaining a specific food.

Objectives
In this laboratory activity, you will:
• learn how structural differences may affect the survival rate of members within a species
• simulate competition for resources among different species of organisms
• see the role of the environment as a selecting agent

Safety
• You should wear safety goggles for this activity.
• Handle the tools carefully. They may have sharp edges and could cause cuts.
• Be especially careful when two or more of you are reaching for seeds at the same time. The “beak” being used by one student has the potential to strike another student.
• Do not taste or eat any of the seeds.
Important Note: Record all of your data and answers on these laboratory sheets. You will need to keep them for review before the Regents Examination. Later, you will need to transfer your answers to a separate Student Answer Packet. Your teacher will use it in grading your work, and the school will retain it as evidence of your completion of the laboratory requirement for the Living Environment Regents Examination.

Materials for Each Team
• 1 small plastic dish or cup • large seeds (such as lima beans)*
• 1 large nonbreakable dish • small seeds (such as lentils)
• 1 tool to serve as a “beak” • 2 pairs safety goggles
* may be needed depending on results of Round One

Procedures (Answer these questions in your answer packet. Below)
1. Examine the different tools (“beaks”) and seeds provided. Predict which “beak” will be the most successful at picking up small seeds. Give the reasons for your choice.
2. Predict which “beak” will be the least successful at picking up small seeds. Give the reasons for your choice.
3. From this point on, you and your partner will model a finch feeding. The tool you were assigned will be your “beak.” Describe what characteristics it has that make it good for picking up small seeds. In the remaining space or on a separate sheet of paper, draw an outline of your assigned “beak.”
4. Both you and your partner should practice transferring the small seeds quickly from the large dish to the small dish before the competition begins. The large dish of small seeds represents the island environment where you live and feed. The small dish represents a finch stomach. Yot may move only one seed at a time. You will receive credit only for a seed that falls into and stays in the small dish.

Round One: No Competition, Original Island
5. When given the “Round One” signal, one member of your team should use the “beak” to pick up small seeds one at a time from the large dish and place them in the small dish. Repeat this for a total of four trials, two trials for each partner. A timekeeper will tell you when to start and stop each trial. Record your results in the “Round One: Feeding with No Competition” data table.

8. Calculate the average number of seeds obtained during the four trials. Round off to the nearest =
seed. If your team collected an average of 13 seeds or more per trial, you can go on to Round Three. If your team collected fewer than 13 seeds per trial, you and your partner are now eliminated.

Round Three: Increased Competition
During this round, you will be competing with all of the other finch species left alive on your island. In other words. all of the finch teams that were successful at feeding on small seeds will compete at one dish containing small seeds. At the same time, all of the fmches successful at feeding on large seeds during Round Two will compete at one dish of large seeds.
9. In the “Round Three: Feeding with Increased Competition” data table, indicate whether you are feeding on small or large seeds. Complete four trials as before and record the results of each trial and your average.

Analysis Questions
1. What characteristics of your “beak” interfered with feeding success on the original island?
2. Name three traits other than beak characteristics that could contribute to the ability of a finch to compete successfully.
3. It is very unlikely that all of the beaks within a species of finch are exactly alike. Random mutations and new gene combinations resulting from sexual reproduction are the source of beak variations. Describe at least three beak variations that could randomly appear and further improve your species’ chances of survival when feeding on small seeds.
4. Why did some “beak” types survive on the new island (with large seeds) when they could not survive on the original island?
5. Class Activity: Complete the Class Results data table on the last page of this laboratory activity before going on to the remaining questions.
6. Did those who were successful in Round One survive equally well when others were competing for food at the same dish during Round Two? Support your answer with an explanation.
7. Why were there fewer survivors at the end of Round Three?
8. At the end of Round Three, were the types of “beaks” that were successful on the new island the same as the types of beaks that were successful on the original island? Support your answer with an explanation.
9. Explain how this activity simulates each of the concepts listed below as they are involved in the process of natural selection. Describe a specific example from this laboratory for each concept.