1. Ecology

2. Introduction: A Tale of Two Fishes
Population ecology is concerned with
Changes in population size
Factors that regulate populations over time
It helps explain the biodiversity of an environment
Copyright © 2009 Pearson Education, Inc.

3. Introduction: A Tale of Two Fishes
Ecologists learn the structure and dynamics of natural populations
With this information they are better equipped to
Develop sustainable food sources
Assess the impact of human activities
Balance human needs with the conservation of biodiversity and resources
Copyright © 2009 Pearson Education, Inc.

4. 36.4 Idealized models predict patterns of population growth
Exponential growth model
The rate of population increases under ideal conditions
Calculated using the equation G = rN
G is the growth rate of the population
N is the population size
r is the per capita rate of increase
Student Misconceptions and Concerns
1. Many students who are not biology majors have trouble thinking about the evolution of systems. One analogy that can be developed, especially for economically-minded students, is the parallels to the “evolution” of businesses. Consider the introduction and expansion of McDonald’s restaurants in the United States over the last 50 years. When McDonald’s restaurants were just starting out, they experienced little competition, with access to many customers. The “population” of McDonald’s restaurants in the United States grew exponentially (or nearly so), with few density dependent factors. However, today McDonald’s restaurants in the U.S. must compete with each other, as well as with many other fast-food restaurants, such as Burger King and Taco Bell. The population of McDonald’s restaurants in the United States has stabilized because of this competition for customers, a density dependent factor. A graph of the growth of McDonald’s restaurants in the United States would likely resemble the lazy “S” shape.
Teaching Tips
1. Exponential growth in a population is like compounded interest on a bank account. The growth of the account is initially small, but as the interest earns interest, the growth expands. $1,000 invested at 7% interest is worth more than $30,000 in 50 years. Consider assigning students to calculate the value of a simple interest-bearing investment over a set period of years, as in the example just noted. Many online financial calculators can perform this task.
Copyright © 2009 Pearson Education, Inc.

5. 500
450
400
350
300
Population size (N)
250
200
150
Figure 36.4A Exponential growth of rabbits.
100 50 1 2 3 4 5 6 7 8 9 10 11 12
Time (months)

6. 36.4 Idealized models predict patterns of population growth
Logistic growth model
This growth model takes into account limiting factors
Limiting factors are environmental factors that restrict population growth
Formula
Student Misconceptions and Concerns
1. Many students who are not biology majors have trouble thinking about the evolution of systems. One analogy that can be developed, especially for economically-minded students, is the parallels to the “evolution” of businesses. Consider the introduction and expansion of McDonald’s restaurants in the United States over the last 50 years. When McDonald’s restaurants were just starting out, they experienced little competition, with access to many customers. The “population” of McDonald’s restaurants in the United States grew exponentially (or nearly so), with few density dependent factors. However, today McDonald’s restaurants in the U.S. must compete with each other, as well as with many other fast-food restaurants, such as Burger King and Taco Bell. The population of McDonald’s restaurants in the United States has stabilized because of this competition for customers, a density dependent factor. A graph of the growth of McDonald’s restaurants in the United States would likely resemble the lazy “S” shape.
Teaching Tips
1. Exponential growth in a population is like compounded interest on a bank account. The growth of the account is initially small, but as the interest earns interest, the growth expands. $1,000 invested at 7% interest is worth more than $30,000 in 50 years. Consider assigning students to calculate the value of a simple interest-bearing investment over a set period of years, as in the example just noted. Many online financial calculators can perform this task.
Copyright © 2009 Pearson Education, Inc.

7. Breeding male fur seals10 8
Breeding male fur seals
(thousands) 6 4
Figure 36.4B Growth of a population of fur seals. 2
1915
1925
1935
1945
Year

8. Number of individuals (N) K
G = rN
(K – N) K
G = rN
Number of individuals (N) K
Figure 36.4C Logistic growth and exponential growth compared.
Time

9. Annual increase (in millions) Total population (in billions)
100 10
Population increase 80 8 60 6
Annual increase (in millions)
Total population (in billions) 40 4
Total population size 20 2
Figure 36.9A Five centuries of human population growth, projected to 2050.
1500
1550
1600
1650
1700
1750
1800
1850
1900
1950
2000
2050
Year

10. 37.1 A community includes all the organisms inhabiting a particular area
Biological community
An assemblage of populations living close enough together for potential interaction
Described by its species composition
Boundaries of the community vary with research questions
Can be a pond
Can be the intestinal microbes of a pond organism
Student Misconceptions and Concerns
1. For many students, understanding ecosystems is like appreciating art. Although both are visible to the naked eye, in each case some background is required to understand the method of composition, the significance of components, and the nature of interactions. The fundamentals introduced in this chapter are new ways to see generally familiar systems.
Teaching Tips
1. Many students have been exposed to diverse ecosystems only through television and movies, which have likely focused on a few species. Before discussing this chapter, consider showing the class a good video (it need not be long) about an ecosystem. The video can then serve as a shared recent experience to which you can relate the content of this chapter. Alternately, you can relate some of the basics of this chapter to a local or regional example with which most students are familiar. There may even be a distinct community on your campus, such as a pond, wooded area, etc., that students could visit and return from with new insights.
2. In human society, a community might be roughly equivalent to a local population, perhaps all the people living in a town or city. The definition of a biological community is more inclusive, comprising all of the populations of organisms living close enough together for potential interaction.
Copyright © 2009 Pearson Education, Inc.

11. 37.2 Interspecific interactions are fundamental to community structure
Interspecific interactions
Relationships with other species in the community
Interspecific competition
Two different species compete for the same limited resource
Squirrels and black bears
Compete for acorns
Student Misconceptions and Concerns
1. For many students, understanding ecosystems is like appreciating art. Although both are visible to the naked eye, in each case some background is required to understand the method of composition, the significance of components, and the nature of interactions. The fundamentals introduced in this chapter are new ways to see generally familiar systems.
Teaching Tips
1. Many students have been exposed to diverse ecosystems only through television and movies, which have likely focused on a few species. Before discussing this chapter, consider showing the class a good video (it need not be long) about an ecosystem. The video can then serve as a shared recent experience to which you can relate the content of this chapter. Alternately, you can relate some of the basics of this chapter to a local or regional example with which most students are familiar. There may even be a distinct community on your campus, such as a pond, wooded area, etc., that students could visit and return from with new insights.
2. In human society, a community might be roughly equivalent to a local population, perhaps all the people living in a town or city. The definition of a biological community is more inclusive, comprising all of the populations of organisms living close enough together for potential interaction.
Copyright © 2009 Pearson Education, Inc.

12. Table 37.2 Interspecific Interactions.

13. 37.3 Competition may occur when a shared resource is limited
Ecological niche
Sum of an organism’s use of biotic and abiotic resources
Interspecific competition occurs when the niches of two populations overlap
Competition lowers the carrying capacity of competing populations
Student Misconceptions and Concerns
1. For many students, understanding ecosystems is like appreciating art. Although both are visible to the naked eye, in each case some background is required to understand the method of composition, the significance of components, and the nature of interactions. The fundamentals introduced in this chapter are new ways to see generally familiar systems.
2. The concept of an ecological niche can be confusing. Ecologist Eugene Odum has suggested that an ecological niche is like an organism’s habitat (address) and its occupation combined.
Teaching Tips
1. Many students have been exposed to diverse ecosystems only through television and movies, which have likely focused on a few species. Before discussing this chapter, consider showing the class a good video (it need not be long) about an ecosystem. The video can then serve as a shared recent experience to which you can relate the content of this chapter. Alternately, you can relate some of the basics of this chapter to a local or regional example with which most students are familiar. There may even be a distinct community on your campus, such as a pond, wooded area, etc., that students could visit and return from with new insights.
2. If your class includes students with business interests, they may enjoy the following analogy. To better understand competition, students might think about fast-food restaurants in your region. Challenge your students to identify the strategies employed by these restaurants to compete with each other. As each restaurant makes changes, does the other restaurant respond? Restaurants changing strategies in response to each other is analogous to coevolution.
Copyright © 2009 Pearson Education, Inc.

14. 37.4 Mutualism benefits both partners
Reef-building corals require mutualism
Photosynthetic dinoflagellates
Live in the cells of each coral polyp
Produce sugars used by the polyps
Provide at least half of the energy used by the coral animals
Student Misconceptions and Concerns
1. For many students, understanding ecosystems is like appreciating art. Although both are visible to the naked eye, in each case some background is required to understand the method of composition, the significance of components, and the nature of interactions. The fundamentals introduced in this chapter are new ways to see generally familiar systems.
Teaching Tips
1. Many students have been exposed to diverse ecosystems only through television and movies, which have likely focused on a few species. Before discussing this chapter, consider showing the class a good video (it need not be long) about an ecosystem. The video can then serve as a shared recent experience to which you can relate the content of this chapter. Alternately, you can relate some of the basics of this chapter to a local or regional example with which most students are familiar. There may even be a distinct community on your campus, such as a pond, wooded area, etc., that students could visit and return from with new insights.
2. Students who are business-oriented may also enjoy this analogy. Many corporate leaders describe the best business deals as mutualistic, fostering a win-win relationship. For example, perhaps a new company creates a marketable product from another company’s wastes.
Video: Clownfish and Anemone
Copyright © 2009 Pearson Education, Inc.

15. Figure 37.4 Coral polyps.

16. 37.7 Parasites and pathogens can affect community composition
A parasite lives on or in a host from which it obtains nourishment
Internal parasites include nematodes and tapeworms
External parasites include mosquitoes and ticks
Pathogens are disease-causing parasites
Pathogens can be bacteria, viruses, fungi, or protists
Student Misconceptions and Concerns
1. For many students, understanding ecosystems is like appreciating art. Although both are visible to the naked eye, in each case some background is required to understand the method of composition, the significance of components, and the nature of interactions. The fundamentals introduced in this chapter are new ways to see generally familiar systems.
Teaching Tips
1. Many students have been exposed to diverse ecosystems only through television and movies, which have likely focused on a few species. Before discussing this chapter, consider showing the class a good video (it need not be long) about an ecosystem. The video can then serve as a shared recent experience to which you can relate the content of this chapter. Alternately, you can relate some of the basics of this chapter to a local or regional example with which most students are familiar. There may even be a distinct community on your campus, such as a pond, wooded area, etc., that students could visit and return from with new insights.
2. Pathogens are probably what most people refer to as germs. Students might believe that these terms refer to some specific type of organism.
Copyright © 2009 Pearson Education, Inc.

17. Figure 37.7 Aphids parasitizing a plant.

18. 37.11 Keystone species have a disproportionate impact on diversity
Keystone species
A species whose impact on its community is larger than its biomass or abundance indicates
Occupies a niche that holds the rest of its community in place
Student Misconceptions and Concerns
1. For many students, understanding ecosystems is like appreciating art. Although both are visible to the naked eye, in each case some background is required to understand the method of composition, the significance of components, and the nature of interactions. The fundamentals introduced in this chapter are new ways to see generally familiar systems.
Teaching Tips
1. Many students have been exposed to diverse ecosystems only through television and movies, which have likely focused on a few species. Before discussing this chapter, consider showing the class a good video (it need not be long) about an ecosystem. The video can then serve as a shared recent experience to which you can relate the content of this chapter. Alternately, you can relate some of the basics of this chapter to a local or regional example with which most students are familiar. There may even be a distinct community on your campus, such as a pond, wooded area, etc., that students could visit and return from with new insights.
2. Many keystone species have been identified in ecosystems, including sea otters, elephants, freshwater bass, and Pisaster, a sea star noted in Figure Challenge your class to explain how the concept of keystone species impacts the efforts of conservation biologists. Why might some species be more important to conserve?
Copyright © 2009 Pearson Education, Inc.

19. Keystone Keystone absent
Figure 37.11A Arch collapse with removal of keystone.

20. Figure 37.11B A Pisaster sea star, a keystone species, eating a mussel.

21. Figure 37.11C Diadema sea urchins grazing on reef.

22. Figure 37.11D Reef overgrown by fleshy seaweeds.

23. 37.12 Disturbance is a prominent feature of most communities
Disturbances
Events that damage biological communities
Storms, fire, floods, droughts, overgrazing, or human activity
The types, frequency, and severity of disturbances vary from community to community
Student Misconceptions and Concerns
1. For many students, understanding ecosystems is like appreciating art. Although both are visible to the naked eye, in each case some background is required to understand the method of composition, the significance of components, and the nature of interactions. The fundamentals introduced in this chapter are new ways to see generally familiar systems.
2. The idea that ecosystems are relatively stable is common. Natural disturbances of any sort (fires, earthquakes, floods, or strong storms) are typically viewed as tragic and damaging to ecosystems. Before beginning the topic of ecological disturbances, consider asking your students to briefly respond to news that a state or federal park has (a) been burned, (b) been struck by high winds and/or lightning, or (c) been temporarily flooded. In addition, consider asking what, if anything, should be done to prevent or repair this damage?
Teaching Tips
1. Many students have been exposed to diverse ecosystems only through television and movies, which have likely focused on a few species. Before discussing this chapter, consider showing the class a good video (it need not be long) about an ecosystem. The video can then serve as a shared recent experience to which you can relate the content of this chapter. Alternately, you can relate some of the basics of this chapter to a local or regional example with which most students are familiar. There may even be a distinct community on your campus, such as a pond, wooded area, etc., that students could visit and return from with new insights.
2. Before and after images of the impact and recovery of an ecosystem from a natural disaster can be more powerful than any verbal explanation of the process.
3. Depending upon your location and its circumstances, consider a short field trip on or near your campus to show disturbed regions and signs of recovery.
Copyright © 2009 Pearson Education, Inc.

24. 37.12 Disturbance is a prominent feature of most communities
Communities change drastically following a severe disturbance
Ecological succession
Colonization by a variety of species
A success of change gradually replaces other species
Student Misconceptions and Concerns
1. For many students, understanding ecosystems is like appreciating art. Although both are visible to the naked eye, in each case some background is required to understand the method of composition, the significance of components, and the nature of interactions. The fundamentals introduced in this chapter are new ways to see generally familiar systems.
2. The idea that ecosystems are relatively stable is common. Natural disturbances of any sort (fires, earthquakes, floods, or strong storms) are typically viewed as tragic and damaging to ecosystems. Before beginning the topic of ecological disturbances, consider asking your students to briefly respond to news that a state or federal park has (a) been burned, (b) been struck by high winds and/or lightning, or (c) been temporarily flooded. In addition, consider asking what, if anything, should be done to prevent or repair this damage?
Teaching Tips
1. Many students have been exposed to diverse ecosystems only through television and movies, which have likely focused on a few species. Before discussing this chapter, consider showing the class a good video (it need not be long) about an ecosystem. The video can then serve as a shared recent experience to which you can relate the content of this chapter. Alternately, you can relate some of the basics of this chapter to a local or regional example with which most students are familiar. There may even be a distinct community on your campus, such as a pond, wooded area, etc., that students could visit and return from with new insights.
2. Before and after images of the impact and recovery of an ecosystem from a natural disaster can be more powerful than any verbal explanation of the process.
3. Depending upon your location and its circumstances, consider a short field trip on or near your campus to show disturbed regions and signs of recovery.
Copyright © 2009 Pearson Education, Inc.

25. 37.12 Disturbance is a prominent feature of most communities
Primary succession
Begins in a virtually lifeless area with no soil
Secondary succession
When a disturbance destroyed an existing community but left the soil intact
Student Misconceptions and Concerns
1. For many students, understanding ecosystems is like appreciating art. Although both are visible to the naked eye, in each case some background is required to understand the method of composition, the significance of components, and the nature of interactions. The fundamentals introduced in this chapter are new ways to see generally familiar systems.
2. The idea that ecosystems are relatively stable is common. Natural disturbances of any sort (fires, earthquakes, floods, or strong storms) are typically viewed as tragic and damaging to ecosystems. Before beginning the topic of ecological disturbances, consider asking your students to briefly respond to news that a state or federal park has (a) been burned, (b) been struck by high winds and/or lightning, or (c) been temporarily flooded. In addition, consider asking what, if anything, should be done to prevent or repair this damage?
Teaching Tips
1. Many students have been exposed to diverse ecosystems only through television and movies, which have likely focused on a few species. Before discussing this chapter, consider showing the class a good video (it need not be long) about an ecosystem. The video can then serve as a shared recent experience to which you can relate the content of this chapter. Alternately, you can relate some of the basics of this chapter to a local or regional example with which most students are familiar. There may even be a distinct community on your campus, such as a pond, wooded area, etc., that students could visit and return from with new insights.
2. Before and after images of the impact and recovery of an ecosystem from a natural disaster can be more powerful than any verbal explanation of the process.
3. Depending upon your location and its circumstances, consider a short field trip on or near your campus to show disturbed regions and signs of recovery.
Copyright © 2009 Pearson Education, Inc.

26. Annual plants Perennial plants and grasses Shrubs Softwood trees
Figure Stages in secondary succession of abandoned farm field.
Annual
plants
Perennial
plants and
grasses
Shrubs
Softwood trees
such as pines
Hardwood
trees
Time