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Natural Selection of Lepidopterans Objectives: To study a population that shows phenotypic and genotypic variation. To see how natural selection can cause adaptive changes in the population. To simulate adaptations that affect a predator’s ability to capture prey. To observe how color affects an organism’s ability to survive in certain environments. Georgia Performance Standards: SB4f. Relate animal adaptations, including behaviors, to the ability to survive stressful environmental conditions. SB5d. Relate natural selection to changes in organisms (changes in a species’ population). PreLab Questions (Background Information for your lab report. Remember to use complete sentences!): 1. What is meant by phenotype? What is meant by genotype? 2. Explain how natural selection is the driving force for evolution. 3. What traits or characteristics would make a bird a successful predator? What traits or characteristics would enable a butterfly to successfully avoid becoming a bird’s prey? 4. Give an example of, or describe what a population would look like, with little or no genetic variation. Under what conditions would this low genetic variability prove detrimental (harmful) to the population? 5. What is the advantage for a population that has several different phenotypes due to a relatively large genetic variability among the members? 6. Formulate two separate hypotheses using the “If…then…because…” format. One hypothesis should predict which hunting adaptation will be most successful for the birds. The second hypothesis should predict which color of Yarn Butterfly will survive best in which habitat. Background Information about this lab: In this lab, students will study the effects of predator adaptations on a population of butterflies and the effects of coloration on natural selection. Students will simulate three different habitats found on an island (volcanic rock, sandy beach, and forest) using construction paper (black and white) and newspaper. Students will investigate one particular species of Yarn Butterfly (prey) which shows at least 5 different phenotypes in wing color. In addition, students will simulate a species of bird (predator) with 2 different hunting adaptations (spoon and fork). Phenotypic variation is an important factor influencing natural selection. Darwin used the term natural selection to indicate that nature (the environment) selects for traits in individuals and those traits which are best suited for the environment enable the organism to survive and reproduce, thereby passing those ‘best suited traits’ on to the next generation. In this way, the frequency of traits within a population can fluctuate over time because some organisms have greater reproductive success than others. Hypotheses: See #5 above Materials: construction paper (black & white), newspaper, timer, plastic fork & spoon, yarn butterflies (10 each of 5 different colors) Procedure: 1. Place all 50 yarn butterflies on your “background” construction paper. 2. Have a group member act as a bird that eats butterflies (the “predator”). Hold the plastic spoon in one hand while sitting on the other hand, capture as many butterflies as possible within a 15 second time period. Remember, the bird can only catch one butterfly at a time. 3. At the end of the 15 second time period, record the number of each of the different colored butterflies captured. 4. Repeat steps 1-3 using black construction paper for the volcanic rock, white for the beach, and newspaper for the forested area. 5. Repeat steps 1-4 using a plastic fork instead of the spoon. Data Record data on the data tables provided Data Analysis Determine which type of graph would display your data best and graph the data. Remember, you can use the free Create-a-Graph tool: (http://nces.ed.gov/nceskids/createagraph/) Conclusion (Answer these questions in the conclusion part of your lab report. Your answers should be supported by the data you collected. Give detailed explanations!) 1. Which hunting adaptation made the birds successful predators? Does your data support your hypothesis? Why or Why not? 2. What could happen to the birds with the less successful adaptation? Explain your answer. 3. What traits (besides using the spoon or fork) could affect the hunting success of the student who was roleplaying the bird? 4. Which butterfly color provided the best protection on the volcanic rock? On the beach? In the forest setting? Does your data support your hypothesis? Were you surprised by the outcome? Why or why not? 5. Why is genetic variation important for a real population? 6. If the volcano on the island undergoes a major eruption and 90% of the forest is destroyed, which color of Yarn Butterfly will be most vulnerable to predation? Explain your answer. 7. How does the scenario played out in this lab help your understanding of natural selection? Data Tables Phenotypic Varieties of Yarn Butterfly Habitat Record quantity of butterflies caught successfully with a spoon! Sunshine Yellow Rockin’ Red Glamorous Green Boisterous Beige Seafoam Green Volcanic Rock Sandy Beach Forest Phenotypic Varieties of Yarn Butterfly Habitat Record quantity of butterflies caught successfully with a fork! Sunshine Yellow Volcanic Rock Sandy Beach Forest Rockin’ Red Glamorous Green Boisterous Beige Seafoam Green