STUDENT PACKET # 6 Student Exploration: Rabbit Population by Season

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1 STUDENT PACKET # 6 Student Exploration: Rabbit Population by Season Name_ Date Big Idea 17: Interdependence Benchmark: SC.7.L.17.2: Compare and contrast the relationships among organisms such as mutualism, predation, parasitism, competition, and commensalism. (Also Assesses SC.7.L.17.1, SC.7.L.17.3) VOCABULARY: population, equilibrium, carrying capacity Winter can be a difficult time. The weather gets colder, days are shorter, and food is scarce. Many parts of North America get snow and ice during the winter. Even with warm clothing and a heated place to live, many people dread the cold of winter and flee south to avoid it. Imagine what it would be like if you were an animal living outside during the winter no heat, no clothing, and little shelter. It can be a challenge for many animals to survive the cold months, and not all animals make it to the spring. When spring comes, it is a time for rebirth. Babies are born, food is again plentiful, and populations rebound from their wintertime lows. The challenges of winter and the bounties of spring are part of a yearly cycle for many animals. Land and Rabbit Population In this activity, you will examine how the amount of land available to rabbits affects the size of the rabbit population. 1. In the Gizmo, look at the Overhead view of land. This is the land that is available for a population of rabbits to live on. Under Land, select Moderate, and be sure that all of the weather Conditions are unchecked. On the DESCRIPTION pane, set the Simulation speed slider to Fast. A. Select the BAR CHART tab. According to the chart, what is the initial population of rabbits? B. Select the GRAPH tab. Click Play ( ), let the simulation run for at least 7 or 8 years, and click Pause ( ). Use the + or - zoom controls to the right of the graph to view the whole graph. What sort of regular yearly pattern do you see in the graph of rabbit population? C. At what time of year does the population decrease? D. At what time of year does it increase? E. Why do you think these annual fluctuations occur? (Note in this simulation, each year begins with spring and ends with winter.) Science Saturday Enrichment Tutorial Page 1

2 F. After 7 or 8 years have gone by, would you say the rabbit population, overall, is increasing, decreasing, or staying about constant? Explain your answer. G. If a population is in equilibrium, it won't show any long-term changes over the years. Is the rabbit population currently in equilibrium? Why or why not? _ G. What appears to be the approximate average rabbit population when the land available to them is moderately sized? _ I. Click Pause and then select the TABLE tab. Scroll through some of the values in the table. Do these values support your earlier answers? If so, how? 2. Under Land, select Little. Return to the GRAPH pane and click Play. A. What changed in the overhead view of land when you changed the land available to the rabbits? B. What happened to the rabbit population when their land was reduced? C. The carrying capacity of an ecosystem is the maximum number of individuals of a species the ecosystem can support. How does reducing the amount of land affect the carrying capacity of this ecosystem? Why do you think this is? D. Watch the population graph for at least 5 or 6 more years. Does the population change appear to be permanent? Why? Science Saturday Enrichment Tutorial Page 2

3 E. What is the approximate average rabbit population on Little land? 3. With the simulation still running and with the GRAPH pane still visible, change the Land setting to Ample. A. What happens to the rabbit population? B. After the population settles (after 5 years or so), what is the approximate average rabbit population? _ C. How did increasing the available land affect the carrying capacity of the ecosystem? Why do you think this is? D. Across the world, the human populations of many countries are rising. What consequences will this have on the land available to wildlife? _ What consequences will this have on the plants and animals that live there? Weather and Rabbit Population In this activity, you will explore how unusual weather conditions affect the rabbit population. 1. Click Reset ( ). Under Land, select Moderate. With the GRAPH pane visible, click Play. A. After the simulation has run for about 5 years, under Conditions, check Harsh winter, What effect does a harsh winter have on the rabbit population? B. Uncheck Harsh winter and let the simulation run until the old equilibrium has been reestablished. Now check Cold spring. What normally happens to the rabbit population in the spring? C. How does a cold spring affect that? Science Saturday Enrichment Tutorial Page 3

4 D. Uncheck Cold spring, let the simulation play for a few years, and then check Hot summer. Describe the effect of a hot summer on the rabbits. E. Uncheck all of the weather conditions and watch the population graph. When the weather returns to normal, does the population rebound to previous levels or does it stay low? Explain. 2. Continue to experiment with various combinations of available land and unusual weather. As you look at the results of each experiment, consider the following questions. A. What type of weather condition or available land setting seems to affect the rabbit population the most? Why do you think this? B. In the long term, which will have a greater affect on rabbit populations, a reduction in land, or a single season of harsh weather? Explain your answer. C. Suppose you were a biologist investigating an endangered species, Based on what you have seen in this Gizmo, what would be the most important thing you could do to increase the population of the species? If possible, discuss your answer with your classmates and teacher Science Saturday Enrichment Tutorial Page 4

5 EXTENSION Lesson of the Kaibab Adapted from an activity at M. Poarch Purpose: 1) To Graph data on the Kaibab deer population of Arizona from 1905 to ) Determine factors responsible for the changing populations. 3) Determine the carrying capacity of the Kaibab Plateau. Background Information: The environment may be altered by forces within the biotic community, as well as by relationships between organisms and the physical environment. The carrying capacity of an ecosystem is the maximum number of organisms that an area can support on a sustained basis. The density of a population may produce such profound changes in the environment that the environment becomes unsuitable for the survival of that species. For instance, overgrazing of land may make the land unable to support the grazing of animals that lived there. Before 1905, the deer on the Kaibab Plateau were estimated to number about The average carrying capacity of the range was then estimated to be about 30,000 deer. On November 28th, 1906, President Theodore Roosevelt created the Grand Canyon National Game Preserve to protect the "finest deer herd in America." Unfortunately, by this time the Kaibab forest area had already been overgrazed by sheep, cattle, and horses. Most of the tall grasses had been eliminated. The first step to protect the deer was to ban all hunting. In addition, in 1907, The Forest Service tried to exterminate the predators of the deer. Between 1907 and 1939, 816 mountain lions, 20 wolves, 7388 coyotes and more than 500 bobcats were killed. Signs that the deer population was out of control began to appear as early as the range was beginning to deteriorate rapidly. The Forest Service reduced the number of livestock grazing permits. By 1923, the deer were reported to be on the verge of starvation and the range conditions were described as "deplorable." The Kaibab Deer Investigating Committee recommended that all livestock not owned by local residents be removed immediately from the range and that the number of deer be cut in half as quickly as possible. Hunting was reopened, and during the fall of 1924, 675 deer were killed by hunters. However, these deer represented only one-tenth the numbers of deer that had been born that spring. Over the next two winters, it is estimated that 60,000 deer starved to death. Today, the Arizona Game Commission carefully manages the Kaibab area with regulations geared to specific local needs. Hunting permits are issued to keep the deer in balance with their range. Predators are protected to help keep herds in balance with food supplies. Tragic winter losses can be checked by keeping the number of deer near the carrying capacity of the range. Procedure: Science Saturday Enrichment Tutorial Page 5

6 1. Graph the deer population data. Place time on the X axis and "number of deer" on the Y axis. DATA TABLE YEAR DEER POPULATION YEAR DEER POPULATION , , , , , , , , , , ,000 Data Analysis: Describe the relationship between the variables: Questions & Conclusions: 1. During 1906 and 1907, what two methods did the Forest Service use to protect the Kaibab deer? 2. Were these methods successful? Use the data from your graph to support your answer. 3. Why do you suppose the population of deer declined in 1925, although the elimination of predators occurred? 4. Why do you think the deer population size in 1900 was 4,000 when it is estimated that the plateau has a carrying capacity of 30,000? 5. Why did the deer population decline after 1924? _ Science Saturday Enrichment Tutorial Page 6

7 ASSESSMENT Big Idea 17: Interdependence Benchmark: SC.7.L.17.2: Compare and contrast the relationships among organisms such as mutualism, predation, parasitism, competition, and commensalism. (Also Assesses SC.7.L.17.1, SC.7.L.17.3) Multiple Choice:Identify the choice that best completes the statement or answers the question. 1 Cleaner fish feed on parasites in a shark's mouth and gills. Which of the following best describes the relationship between the cleaner fish and the shark? A competitive. B mutualistic. C Nonexistent. D parasitic. 2 Some animals in the northern latitudes have to migrate south in order to survive. What abiotic factor causes the animals to annually leave their ecosystems? F heavy rains G less oxygen H cold weather J increased sunlight 3 The removal of plant material, such as grass clippings, would MOST likely affect an ecosystem by A decreasing the potential for soil erosion. B increasing the food available for consumers. C decreasing the nutrients available for new plants. D increasing the accumulation of organic materials. 4 Scientists have discovered that there has been a reduction in the butterfly population in an ecosystem. After much research, they have identified that the carrying capacity for butterflies has been decreased. If the scientists want to increase the butterfly population, which action should they recommend? F removing primary producers G spraying of insecticides H increasing runoff J planting flowers 5 In 1989, an oil spill off the coast of Alaska led to a decline in the population of many organisms. Which other population was MOST likely affected by the drop in population of the fish, otters, and seals? A Deer B Eagles C Frogs D Snakes Science Saturday Enrichment Tutorial Page 7

8 6 In the geologic past, abiotic factors such as volcanic eruptions have had an impact on the availability of resources. How can volcanic eruptions impact the availability of resources? F carbon dioxide G minerals H sunlight J water 7 In any ecosystem, the survival of a species depends on the resources that are available. Beneath the tree canopy in a tropical rainforest, growth of some plant species may be limited. The availability of which of these resources most likely limits the growth of plants on the ground level in this ecosystem? A Less solar radiation would enter the region. B Larger plants and trees would take over the region. C The region would become a habitat for large and small sea organisms. D The primary producers in the region would have less ability to recycle carbon. 8 Wildcats, such as the lynx, are predators of rabbits. Which will MOST likely occur if a new, aggressive species of wolf is introduced into the ecosystem that is a predator of the lynx? F The new species population will consume the food that the rabbits eat. G The population of the rabbits in the ecosystem will increase. H The new species population will be consumed by the lynx. J The population of the lynx in the ecosystem will increase. 9 In a grassland ecosystem, organisms of the same species eat the same food. When there is a lack of rain, which is MOST likely increased? A carrying capacity B population density C competition for space D competition for resources 10 Wolves, which are top predators, were eliminated from Yellowstone National Park in the 1930s. In 1995, wolves were reintroduced into Yellowstone. During the period in which wolves were absent from Yellowstone, which MOST likely occurred? F an increase in competition for food resources among small prey G a greater opportunity for primary producers to flourish H an increase in the population of tertiary consumers J a greater balance of predator-prey relationships 11 Which of the following is an example of parasitism? A. bees and flowers B. a tick on a dog C. barnacles attached to a whale D. a wolf and a rabbit Science Saturday Enrichment Tutorial Page 8