Understanding Population Ecology: Wolves, Moose, and Distribution Patterns

Study Guide Chapter 20: Population Ecology On the Tracks of Wolves and Moose: Ecologists learn big lessons from a small island Driving Question 1: What is ecology, and what do ecologists study? Why should you care? The study of ecology is becoming increasingly important as concern grows about the effect of environmental degradation on human health and well-being. Ecology is studied at many different levels; knowing the difference between the levels of ecology will help you understand and interpret ecological information. Have you ever looked at a photo of North America at night? If you have, you might have noticed that there is an interesting pattern of lights: all of the coasts are outlined; there’s a scattering of lights throughout the eastern half of the continent; and most of the western interior is dark. The superficial reason for this pattern is immediately apparent—the lights indicate where the biggest populations of people live. However, the deeper questions of what historical, cultural, economic, and geographical factors have caused this distribution of people are much more complex. Just as a sociologist might want to study the distribution of people, ecologists often need to study the distribution pattern of various organisms; they tailor their studies to the nature of the organisms, so that they can learn the right questions to ask about why those organisms live where they do. Understanding how organisms distribute themselves reveals how they interact. Think again of human interactions: how would four strangers arrange themselves in an elevator? Would you expect them to bunch up in the same corner or distribute themselves uniformly into each corner of the space? People tend to want to give each other space in close quarters. If you increase the scale, however, to human interactions at the neighborhood or town level, you will see that their distribution tends to be clumped: there are subdivisions, apartment complexes, and town homes. This tends to occur because of the distribution of suitable land for housing, utilities, and the zoning restrictions put in place by local governments. Just as much can be learned from the way people arrange themselves, much can also be learned about the way other organisms are distributed. What should you know? To fully answer this Driving Question, you should be able to: 1. Diagram the nested levels of interactions in ecology. 2. Explain how distribution patterns may affect population sampling methods. 3. Explain the differences among random, clumped, and uniform distribution patterns. 4. Explain what factors create distribution patterns.

Infographic Focus: The infographics most pertinent to the Driving Question are 20.1, 20.2, and 20.3. 1. Diagram the nested levels of interactions in ecology. The different levels of ecology can be thought of as nested within each other. In each of the circles below, arrange the following levels from most inclusive in the largest circle to least inclusive in the smallest circle: ● Community ● Ecosystem ● Individual ● Population Then, draw a line to connect each level to the best example of how an ecologist might conduct research at that level.  Studying how a white oak tree deals with water stress  Studying how white oak trees, squirrels, and birds interact with each other and deal with a drought  Studying how a group of white oak trees compete with each other for space and light in a forest  Studying how white oak trees manage to reproduce despite heavy seed predation from squirrels. ECOSYTEM Community POPULATION INDIVIDUAL

2. Explain how distribution patterns may affect population sampling methods. Distribution patterns may cause sampling methods to be easier or harder. Why is it more difficult to spot moose than wolves on Isle Royale? Moose are usually solitary and are distributed randomly on Isle Royale. Compare and contrast the methods used by researchers to study moose populations to the methods used to study wolf populations. Since wolves travel in packs it’s easy to spot and count them individually however moose are randomly distributed causing them to only be able to be counted in a series of plots of land and then be averaged out to get a total number. 3. Explain the differences among random, clumped, and uniform distribution patterns. Random distribution means individuals can be anywhere within an area, Clumped distribution means they go wherever the resources are, Uniform distribution means individuals are strategically separated. Using dots, flowers, or animals, draw the difference between distribution patterns. Random Clumped Uniform 4. Explain what factors create distribution patterns. The way resources are distributed across an area as well as interactions among the members of the population create distribution patterns. Propose an example of organisms that would display the following patterns: Random: Moose Clumped: School of fish Uniform: Penguins

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version

Access to all documents
Unlimited textbook solutions
24/7 expert homework help

Review Questions 1. True or False: Ecologists may study the effect of environment on a single organism as well as an entire community of species. True 2. An underwater animal population that relies on touch to exchange chemical signals among individuals in the population would likely be distributed in this pattern: A. Random B. Clumped C. Uniform 3. True or False : Changes (i.e., genetic, environmental, etc.) at the individual level do not affect the ecosystem. 4. True or False : Changes (i.e., genetic, environmental, etc.) at the population level do not affect the ecosystem. 5. True or False : Changes (i.e., genetic, environmental, etc.) at the community level do not affect the ecosystem. Driving Question 2: What are the different types of population growth? Why should you care? All organisms experience population growth and have upper limits to their population size . . . including humans. The global human population has been growing exponentially for the last century, and evidence suggests that we are approaching the upper limit of sustainable population. Learning about population growth and carrying capacity in other organisms will help you understand what humans are facing. For populations of predators such as the wolves on Isle Royale to continue to exist, they must have an adequate supply of prey. If they were to eat all the moose and other prey animals on the island, they would die out. Instead, populations of wolves and moose periodically oscillate. Studying why and how this happens may help humans continue to exist. A central truth in ecology is that everything is connected. We often forget that we are part of nature, not outside of it. Just as ants modify their environment by building colonies, we modify our environment by creating cities. The level and complexity of how we change the world to suit our purposes may be greater than most animals, but we are still animals living and affecting nature. Realizing that we are still connected to the environment is important. What should you know?

To fully answer this Driving Question, you should be able to: 1. Compare and contrast exponential and logistic population growth. 2. Demonstrate how population growth rate is calculated. 3. Define and explain the role of carrying capacity in the growth of populations. Infographic Focus: The infographic most pertinent to the Driving Question is 20.4. Test Your Vocabulary: [GROWTH RATE] Difference between the birth rate and death rate [IMMIGRATION] Movements of individuals into a population [EMIGRATION] Movement out of a population [EXPONENTIAL GROWTH] Unrestricted growth of a population that is increasing at a constant rate [HABITAT] The physical environment in which an animal lives [LOGISTIC GROWTH] Starts off fast and then levels off due to environmental factors and the ability to reproduce [CARRYING CAPACITY] The maximum number of individuals an environment can support. 1. Compare and contrast exponential and logistic population growth. Exponential means that the population is growing at a fixed percentage every generation whereas logistic population growth starts rapidly and then slows down Draw an exponential population growth curve and a logistic population growth curve in the spaces below. Be sure to label both axes appropriately. Exponential Growth Logistic Growth

In what conditions would you expect to find exponential growth occurring? And logistic growth? If a population does not have a limit on resources then exponential growth will occur. If a population does have a limit on resources then logistic growth will occur. 2. Demonstrate how the population growth rate is calculated. Birth rate minus Death rate Fill in the boxes below to describe the relationship of birth rate and death rate to total population growth rate, assuming immigration and emigration are not occurring. - = Explain the equation in your own words. If the birth rate and death rate are equal, we have no growth, If more people are born then those who die will equal a positive growth rate. If more people die than are born equals a negative birth rate 3. Define and explain the role of carrying capacity in the growth of populations. Carrying capacity is the maximum number of individuals a population can have based on resources. What is carrying capacity in terms of population growth? Carrying capacity is how large a population can grow based off of resources and food availability. Growth rate Death Rate Birth Rate

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version

Access to all documents
Unlimited textbook solutions
24/7 expert homework help

What factors do you think can influence the total number of wolves on Isle Royale? Availability of food, the environment and disease What factors do you think can influence the total number of moose on Isle Royale? Predation from wolves and availability of food Why do you think the line of the logistic population graph wavers back and forth at the carrying capacity? Because a population should be at or below carrying capacity. Thought Question: Do you think the human population is below, at, or above its carrying capacity? Why ? I think humans are above its carrying capacity because there are not enough natural resources to support us Review Questions 1. In the absence of immigration and emigration, a growth rate of zero means that the: A. birth rate is zero. B. death rate is zero. C. population is not affected by environmental factors. D. birth rate and death rate are equal. 2. True or False : A population with a logistic growth rate will grow indefinitely.

Driving Question 3: What factors influence population growth and population size? Why should you care? Both living and nonliving conditions can influence the populations of an organism, whether they are wolves, trees, moose, or people. In humans, abiotic factors that affect population growth are natural disasters, climate, and availability of resources such as clean water. Biotic factors include diseases, birth rates, and death rates. Global climate change is accepted by most scientists, especially ecologists, and ecologists are especially concerned about the effects of changing climate on ecosystems. Why should you care? Some of the predicted effects include the proliferation of organisms that spread disease, such as mosquitoes that carry malaria. What should you know? To fully answer this Driving Question, you should be able to: 1. Interpret fluctuating patterns of prey and predator populations over time. 2. Explain the interrelationships among predator population size, prey population size, and prey food source abundance, using an example from the text. 3. Explain the various ways the health of study animals can be assessed indirectly from their scat, urine, and blood. 4. Explain how abiotic and biotic factors influence predator and prey population size. 5. Differentiate between density-dependent and density-independent influences on predator and prey population sizes. Infographic Focus: The infographics most pertinent to the Driving Question are 20.5, 20.6, 20.7, 20.8, and 20.9. Test Your Vocabulary: [POPULATION DENSITY] Number of organisms per given area [DENSITY-DEPENDENT FACTOR] A factor that influences population size and growth depends on the number and crowding of individuals in the population [BIOTIC] Living components of an environment [DENSITY-INDEPENDENT FACTOR] A factor that influences population size and growth regardless [ABIOTIC] nonliving components of an environment

1. Interpret fluctuating patterns of prey and predator populations over time. Examine Infographic 20.5; describe any patterns that you see in the populations of wolves and moose. It’s clear that whenever the wolves’ population is high moose population is low but when the moose population is high wolves’ population is low. Can you think of any reasons for the patterns you described? Disease, Lack of food , inbreeding and climate change has brought the wolf population down. 2. Explain the interrelationships among predator population size, prey population size, and prey food source abundance, using an example from the text. Examine Infographic 20.6. Add notes to each arrow below, describing how trees, wolves, and moose affect each other’s populations. 3. Wolves Moose Trees

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version

Access to all documents
Unlimited textbook solutions
24/7 expert homework help

3. Explain the various ways the health of study animals can be assessed indirectly from their scat, urine, and blood. What information can be gathered from the droppings of wolves and moose? DNA , Genetic profile , What they are eating. What information can be determined from urine? Nutritional Health What information about a moose’s health can be determined from their bones? The presence of arthritis and osteoporosis, nutritional health 4. Differentiate between density-dependent and density-independent influences on predator and prey population sizes. Describe the difference between a density-dependent and a density-independent control on a population. A density-dependent control depends on the number and crowding of individuals in the population whereas density-independent control does not. Thought Question: Can humans have an effect on abiotic factors? Why or why not? Yes humans can have an effect on abiotic factors because of our contribution to climate change Review Questions 1. True or False : In the long-term, it is better for the moose population to exist in high- density numbers, so that they may protect themselves from wolf attacks. 2. Which of these is NOT an abiotic factor that influences moose populations? A. climate B. temperature C. availability of fresh leaves D. availability of water E. neither climate nor temperature

3. True or False: Trees on Isle Royale do not typically grow as much in years that the wolf population is down.

shuster_bcw4e_chapter_20_Study Guide (1)

Related Documents