Investigation Bird Beak Adaptations Lab Activity

Transcription

1 Investigation Bird Beak Adaptations Lab Activity Name Date Period Score 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 s 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. Each island has its specific food. 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 Procedure: You and your classmates will represent four different types of birds. Along one of your many journeys, you discover a variety of islands. After closer inspection, you notice that each island contains a different type of food for birds. It is up to you to visit each island, compete with various structures of beaks, and then relate their structure to their function. Each test will allow you to see how different bird beaks are adapted to their food source. 1. There are 4 different islands. Each has a unique environment, and in turn, has a unique food source for birds: a. Aquatic Vegetations c. Seeds b. Worms d. Nectar 2. All 4 types of bird beaks will be tested at each island a. s b. s c. d. Test tube holders 3. You will be divided into groups of 4 Part 1: Predict and Hypothesize 4. Begin at one of the four islands. Note the type of food at each island and hypothesize what bird or beak would be best suited for this particular island. Explain your reasoning Record your information in Data Table 1 5. Repeat step 4 for each island 1

2 Table 1: Predictions Type of food What will a bird have to do to obtain food? 1 Which beak will work the best in obtaining the food? Explain Why Part 2: The Best Beak Competition 6. Go back to your first 7. Each has specific rules for obtaining food. Make sure you read each one and follow the directions carefully 8. The competition: On person in the group will use one of the four beaks to consume as much food in 15 seconds as possible. It does not matter what beak you start out with. 9. Make sure to record each bird s consumption of food in 15 seconds in Data Table Replenish the food after each trial. 11. Three trials will be performed using each beak following the procedure described above. 12. After completing the three trails per beak, calculate the average of the three trials in order to determine the average amount of each food consumed. 13. Perform one competition round for each ; use all 4 beaks in one 20 second round 14. Once your data is complete, you can determine which beak was best suited for the food on each island. Record your decisions in Table Discuss the structural advantage of the best beak on each island and why it was best suited. Record in Table 2. 2

3 Table 2: Observations Beak Type Trial 1 Trial 2 Trial 3 Average Competition Round Which "beak" worked the best? Describe the structural advantage #1: Aquatic Vegetation #2: Worms #3: Seeds #4: Nectar Analysis Questions 1. What characteristics of your "beak" interfered with feeding success on an island in which your beak was outcompeted? 2. Name three traits other than beak characteristics that could contribute to the ability of a finch to compete successfully. 3

4 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 seeds, worms, aquatic vegetation, and nectar. 4. Why did some beak types survive on one island when they could not survive on another? 5. Were those who were successful on #2 equally successful on #3? Support your answer with an explanation. 6. 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. variation: competition: struggle for survival: adaptation: environment: selecting agent: 4

5 Base your answers to questions 6-8 on Figure 1, which shows various finches found on the Galapagos s, and on your knowledge of biology. 7. Predict which species of finch would be most likely to survive if the weather on the Galapagos s gradually changed and the seeds available to the finches became larger with heavier coverings. Support your answer with an explanation. 8. One island is populated by two species Ground Finches and Small Tree Finches. a. What two types of food would you expect to be available on this island? Support your answer with an explanation. 5

6 b. Would you expect the two species to compete for food on this island? Support your answer with an explanation. c. How might the two native finch populations be affected if several dozen Sharp-billed, Ground finches were to migrate to the island and survive? Support your answer with an explanation. 9. a. Explain how an island could support large populations of both Large Ground Finches and Small Ground Finches. b. How could you use the materials provided in this lab to test your explanation. 6

7 Teacher Set up and Directions for Students #1 Aquatic Vegetation: Corks floating in water Students pick up corks one at a time and place them in their dish Measurement: number of corks Put food back after each trial #2 Worms Cut up pipe cleaners scattered on and in potting soil Students pick up pipe cleaners one at a time and place them in their dish Measurement: number of pipe cleaners Put food back after each trial put some into the soil and on top #3 Seeds Beans in an aluminum pan Students pick up beans one at a time and place them in their dish Measurement: # beans Put food back after each trial #4 Nectar Colored water in a bowl or large beaker Students pick up as much water as they can and pour it into a graduated cylinder Measurement: volume of colored water in graduated cylinder Pour water back after each trial 7