Natural and Artificial Selection Gizmo Answer Key

Name: Jaylee Mcmillan Date: 05-15-2022 Student Exploration: Evolution: Natural and Artificial Selection Directions: Follow the instructions to go through the simulation. Respond to the questions and prompts in the orange boxes. Vocabulary: artificial selection, breed, chromosome, evolution, fitness, genotype, mutation, natural selection, phenotype [Note to teachers and students: This Gizmo was designed as a follow-up to the Evolution: Mutation and Selection Gizmo. We recommend doing that activity before trying this one.] Prior Knowledge Question (Do this BEFORE using the Gizmo.) This illustration from an old textbook shows some of the over 150 different dog breeds that can be seen around the world today. How do you think all of these different breeds were developed? The majority of them were crossbred with various varieties. in order to develop different breeds. Gizmo Warm-up Dog breeds and other varieties of domesticated animals were developed through artificial selection. Over many generations, breeders selected which animals to mate in order to select for desired traits. The Evolution: Natural and Artificial Selection Gizmo allows you to try your hand at breeding insects with a variety of colors. To begin, select the Artificial selection option. 1. Drag the 10 insects into the breeding alcoves on the left side of the Gizmo. A. How many breeding pairs are there? 5 pairs B. How many offspring are produced? 20 children total were born to the five breeding partners. 2. Circled insects have mutations, or changes to their DNA. How many of the offspring insects in this generation have mutations? 1 only Activity A: Get the Gizmo ready: Genotype and phenotype ● Select Natural selection. Question: How are genes inherited and modified over many generations? 1. Observe: The fitness of an insect is a measure of how well it is adapted to its environment. A. What is the initial Average fitness of these insects? B. Click Play ( generation? 50% ), and observe the simulation for several generations. What occurs in each Half of each generation is devoured as it is born, but the other half keeps reproducing and the population rises for several generations. C. Increase the Sim. speed by one level. Click Pause ( fitness now? ) after 30 generations. What is the Average 83% 2. Analyze: Set the Sim. speed to its slowest level. Click Play, and then Pause when the offspring appear. Choose a pair of parents in which both parents have a different color. A. Move your cursor over a parent insect. The genes that control color make up an insect’s genotype, while its actual color is its phenotype. Fill in the genotypes and phenotypes of each parent below. Parent 1 genotype Parent 1 phenotype Parent 2 genotype Parent 2 phenotype Red= 85 Red= 85 Green= 255 Green= 213 Blue = 170 Blue = 128 Now list the genotypes of each of the four offspring below. Offspring 1 Offspring 2 Offspring 3 Offspring 4 W G C W G C W G K W G C W G C W G C W G K W G C 3. Explain: Each rod-shaped structure is a chromosome. Real chromosomes contain hundreds or even thousands of genes. The simplified chromosomes shown in this Gizmo only contain genes that determine the insects’ colors. How are the chromosomes of the offspring related to the chromosomes of the parents? Because chromosomes are passed from parents to offspring during reproduction, the chromosomes of the offspring are connected to those of the parents. 4. Investigate: Any insect that has a mutation will be circled. Place your cursor on an insect with a mutation to examine its genotype. (If there are none in this generation, click Play and then Pause when a mutation appears.) A. Examine the genotype of the mutated insect as well as the genotypes of its parents to determine what the mutation is. What new gene appeared? Y B. Do you think this mutation is helpful, harmful, or neutral for the insect? Explain. Helpful,since there would be a chance of not getting eaten by the predator. C. Click Play, and then click Pause after the birds have finished eating. Did the mutated insect survive? Yes, it did 5. Observe: Increase the Sim. speed by two levels. Click Play, and wait for a while. What occurs as time goes by? A bird still consumes an insect with a different mutation. 6. Explain: In wild populations, evolution is often caused by natural selection. Based on what you have observed, how does natural selection occur? For several generations, the cycle repeats itself and offspring with different genes survive and pass them on to subsequent generations. Activity B: Artificial selection Get the Gizmo ready: ● Select Artificial selection. ● Set the Mutation rate to 2.0. Question: How can a species be changed through artificial selection? 1. Set a goal: In this activity, your goal is to develop insects that are any color you would like. What color do you want your insects to be? Blue 2. Make a plan: Follow the directions in the Gizmo to produce five generations of insects. A. How would you describe the process of artificial selection? It's a process where you decide which genotype instinct to combine with to produce a breed with a specific genotype to your preference. B. How will mutations be useful in achieving your goal color? The DNA sequence will change as a result of mutations, allowing the color of the instinct to be altered. C. What strategy will you use to produce insects of your desired color? Artificial selection, as I would like to have a certain type right now. But given that getting there will require natural selection, I'll choose that route. 📷 3. Run Gizmo: Use the Gizmo to produce insects that match your goal color. (This will take patience!) When you are satisfied, click the camera ( ) to take a screenshot. Right-click the image and choose Copy Image, and then paste the image below. How many generations did it take for you to develop your insects? 1403 4. Compare: If possible, compare your insects to the insects developed by your classmates. What different colors of insects can be developed using artificial selection? Everyone is unique. 5. Explain: One of the tallest dog breeds is the Great Dane, which stands over a meter tall. One of the shortest is the Pomeranian, which stands about 20 centimeters tall. Based on what you have learned about artificial selection, how were these two breeds developed? Must select parents who have the proper variances. For example, if you wanted to develop a small dog breed, you would simply breed your smaller dogs, then select their smallest children to breed the following generation, and so on until you had the size you wanted. 6. Collect data: Use the Red, Green, and Blue sliders to match the Background color as closely as possible to phenotype of the insects. Select Natural selection. Click Play, and then click Pause when the Average fitness first exceeds 90%. Record the number of generations in the table below, and then repeat for a total of five trials. Trial 1 2 3 4 5 Mean Number of generations to achieve 90% fitness Blue 57 Green 107 Purple 77 Yellow 81 Pink 53 75 7. Calculate: Add up the number of generations and divide by five to find the mean number of generations required to reach at least 90% fitness. Fill in the last column of the table. 8. Analyze: Which process tends to occur more quickly, natural selection or artificial selection? Why do you think this is so? Natural selection, since I have the power to alter the color of nature, as opposed to artificial selection, which would have required several generations to change. However, I would have the power to alter the DNA of the species, which would have required only a few generations. 9. Summarize: How are the processes of natural selection and artificial selection similar? How are they different? If possible, discuss your answer with your classmates and teacher. Changes in plants and animals can result from both natural and artificial selection. Natural selection takes place naturally, whereas artificial selection only happens when humans get involved. Activity C: Get the Gizmo ready: ● Click Reset ( ). Be sure Natural selection is selected. ● Set Red to 100, Green to 255, and Blue to 50. Mutation rates Question: How does the mutation rate affect a population’s ability to adapt to its environment? 1. Gather data: Change the Mutation rate to 0.1 and the Sim. speed slider to its lowest setting. Click Play, and then click Pause when the offspring appear. Record the number of mutations (circled offspring), and then repeat for two more trials. Do this for each mutation rate listed in the table, then calculate the mean number of mutations for each mutation rate. Mutation rate 0.1 Trial 1 0 Trial 2 0 Trial 3 0 Mean 0 1.0 0 1 1 0.66 10.0 13 12 10 11.66 How does the mutation rate relate to the number of mutations in each generation? They are about the same number where the mutation is 0.1 the end result is 0. 2. Form hypothesis: How do you expect the rate of mutations to affect the ability of the bug population to adapt to its environment? Since the number of distinct children depends on the rate of mutation, it will have an impact. 3. Gather data: Click Reset. Set the Mutation rate to 0.1, and move the Sim. speed slider to a faster setting. Click Play, and then click Pause when the Average fitness is 90% or greater. Record the number of generations required to reach 90% fitness in the table below. Mutation rate 0.1 Number of generations to 90% average fitness Trial 1 Trial 2 Trial 3 261 651 991 Mean 634 0.3 241 231 461 311 0.5 221 171 291 227.66 1.0 121 161 161 147.66 3.0 131 101 151 94 5.0 121 121 141 94.33 10.0 131 141 141 137 4. Analyze: How does the mutation rate affect the speed at which a population adapts to its environment? To reach the Average fitness, fewer generations are required. 5. Think and discuss: You may have noticed that above a certain mutation rate the time required for a population to adapt to its background may increase. Why do you think this is so? If possible, discuss your answer with your classmates and teacher. Not all bugs can adjust to new environments or ways of life. Additionally, these bugs are hunted by predators, which reduces their abundance. It ultimately results in a slow increase in population. 6. Apply: Scientists doing artificial breeding experiments often use radiation or other methods to increase the mutation rate. Why is a high mutation rate useful? High mutation is advantageous because features will emerge and integrate into the population's genetic makeup. 7. Investigate: Use the Gizmo to develop a population of insects that are well adapted to their environment. (Average fitness is above 90%.) Change the Mutation rate to 0.1, and run the simulation. Then, observe the population with a Mutation rate of 10.0. A. What do you notice? That whereas it takes a long time for the mutation rate to reach the average fitness and never exceeds 90%, it happens quite quickly for the mutation rate of 0.1. B. If a population is already well-adapted to its environment, will most mutations be helpful or harmful? Explain. It will be helpful because the adaption is already adapted to its environment. But if changes where to be made to the environment the bug will more likely not survive and the population will go down eventually.