Student Exploration Rabbit Population by Season

Name: Date: Student Exploration: Rabbit Population by Season Directions: Follow the instructions to go through the simulation. Respond to the questions and prompts in the orange boxes. Vocabulary: carrying capacity, density-dependent limiting factor, density-independent limiting factor, limiting factor, population, population density Prior Knowledge Questions (Do these BEFORE using the Gizmo.) 1. Suppose you had a pet rabbit. What would the rabbit need to stay alive and healthy? The rabbit would need fresh food and water every day as well as a clean shelter with a survivable temperature. 2. A female rabbit can give birth to over 40 baby rabbits a year. Suppose all of her offspring survived and reproduced, all of their offspring survived and reproduced, and so on. If that happened, in only eight years the mass of rabbits would exceed the mass of Earth! So, why aren’t we overrun with rabbits? What keeps the rabbit population in check? Rabbits are lower on the food chain because they are prey to animals like hawks, owls, and eagles which keep their population in check. Gizmo Warm-up A population is a group of individuals of the same species that live in the same area. The size of a population is determined by many factors. In the Rabbit Population by Season Gizmo, you will see how different factors influence how a rabbit population grows and changes. 1. Select the BAR CHART tab. What is the size of the initial rabbit population? 40 2. Select the TABLE tab. Click Play ( one year. ), and allow the simulation to run for A. In which season did the rabbit population increase the most? Spring B. In which season did the rabbit population increase the least? Winter Activity A: Carrying capacity Get the Gizmo ready: ● Click Reset ( ). Question: What determines how large a population can grow? 1. Think about it: A limiting factor is any factor that controls the growth of a population. What do you think are some of the limiting factors for the rabbit population? The amount of food available and the rabbits’ predators. 2. Run Gizmo: Select the DESCRIPTION tab. Set the Simulation speed to Fast. Select the GRAPH tab. Click Play, and allow the simulation to run for at least 10 years. (Note: You can use the zoom controls on the right to see the whole graph.) A. Describe how the rabbit population changed over the course of 10 years. The population steadily grew for over half of the 10 years but then began to decline at a constant rate. B. What pattern did you see repeated every year? In the spring, the population grew exponentially before declining in winter. C. How could you explain this pattern? Food becomes scarcer for rabbits in winter so their population declines, 3. Analyze: The carrying capacity is the maximum number of individuals of a particular species that an environment can support. All environments have carrying capacities. A. What is this environment’s approximate carrying capacity for rabbits? (Note: Average the summer and winter carrying capacities.) The total average is 384 with 426 during the summer and 342 during the winter. B. When did the rabbit population reach carrying capacity? Explain how you know. The rabbit population hit carrying capacity during the summer and spring months, because the population stopped rising and stayed constant. Activity B: Get the Gizmo ready: Density-dependent limiting factors ● Click Reset. ● On the SIMULATION pane, make sure Ample is selected for the amount of LAND available. Introduction: Population density is the number of individuals in a population per unit of area. Some limiting factors only affect a population when its density reaches a certain level. These limiting factors are known as density-dependent limiting factors. Question: How does a density-dependent limiting factor affect carrying capacity? 1. Think about it: What do you think some density-dependent limiting factors might be? Food availability, shelter, predators 2. Predict: Suppose a shopping mall is built near a rabbit warren, leaving less land available for rabbits. How will this affect the environment’s carrying capacity? Less land would mean less food and shelter and resources for the rabbits, so the population will decline 3. Experiment: Use the Gizmo to find the carrying capacity with Ample, Moderate, and Little land. List the carrying capacities below. Ample: 402 300 Moderate: 109 Little: 4. Analyze: How did the amount of space available to the rabbits affect how many individuals the environment could support? More space available supported a larger population. 5. Infer: Why do you think limiting a population’s space decreases the carrying capacity? It changes the food availability. 6. Challenge yourself: Other than space, what might be another density-dependent limiting factor? Explain. Predators are another density-dependent limiting factor because competition between predators causes them to fight for food and fight for resources to stay alive. Activity C: Density-independent limiting factors Get the Gizmo ready: ● Click Reset. ● On the SIMULATION pane, select Ample for the amount of LAND available. Introduction: Not all limiting factors are related to a population’s density. Density-independent limiting factors affect a population regardless of its size and density. Question: How do density-independent limiting factors affect how a population grows? 1. Think about it: What do you think some density-independent limiting factors might be? Weather conditions, environmental pollution, temperature 2. Gather data: Click Play. Allow the population to reach carrying capacity. Click Pause ( ). Select the GRAPH tab and click the camera ( ) to take a snapshot of the graph. Right click the image and paste the snapshot into the box below. Label the graph “Normal Weather.” Normal weather 3. Predict: How do you think a period of harsh winters will affect the rabbit population? It will cause the rabbit population to decrease. 4. Investigate: Click Reset. Select Harsh winter from the CONDITIONS listed on the SIMULATION pane. Click Play, and observe how the population changes over five years. Paste a snapshot of the graph in the box below. Label the graph “Harsh Winter.” Harsh winter A. How does the Harsh Winter graph differ from the Normal Weather graph? The values in the Normal Weather graph fluctuate between relatively constant values while the Harsh Winter graph shows an increase over time with a drastic decrease in the winter season, B. What do you think most likely caused the differences seen in the two graphs? Food is scarce in winter so the population decreases. 5. Predict: Rabbits reproduce in the spring. How do you think a period of cold springs will affect the rabbit population? It will cause it to decrease drastically. 6. Investigate: Deselect Harsh winter. Select Cold spring. Click Play, and observe how the population changes over a period of five years. Paste a snapshot of the graph in the box below and label the graph “Cold Spring.” Cold spring A. How does the Cold Spring graph differ from the Normal Weather graph? The Cold Spring graph shows an increase over time with a short decrease while the Normal Graph is more constant. B. What do you think most likely caused the differences seen in the two graphs? Weather and food availability 7. Predict: How do you think a period of hot summers will affect the rabbit population? There will be a steady increase with a small decrease during the winter months. 8. Investigate: Deselect Cold spring. Select Hot summer. Click Play, and observe the how the population changes over a period of five years. Paste a snapshot of the graph in the box below. Label the graph “Hot Summer.” Hot summer A. How does the Hot Summer graph differ from the Normal Weather graph? The hot summer graph increases greatly compared to the normal graph. B. What do you think most likely caused the differences seen in the two graphs? There is greater food availability in the hot summer months than in the colder months. 9. Think and discuss: Other than unusual weather, what might be another density-independent limiting factor that could affect the rabbit population? If possible, discuss your answer with your classmates and teacher. Another density-independent factor could be pollutants in the environment or even air quality or soil nutrition.