Chapter 36 Population Ecology.

Chapter 36 Population Ecology

Biology and Society: Multiplying Like Rabbits
In 1859, 12 pairs of European rabbits were released on a ranch in southern Australia. By 1865, 20,000 rabbits were killed on just that one ranch. By 1900, several hundred million rabbits were distributed over most of the continent. © 2010 Pearson Education, Inc.

Figure Rabbit plague Figure 19.00

The European rabbits Destroyed farming and grazing land Promoted soil erosion Made grazing treacherous for cattle and sheep Competed directly with native marsupials

The European red fox Was introduced to control the rabbits Spread across Australia Ate several species of native birds and small mammals to extinction Had little impact on the rabbit population

Today, rabbits, foxes, and a long list of other non-native animal and plant species are
Still entrenched in Australia Damaging the environment Costing hundreds of millions of dollars in economic losses

Ecology 1. the study of how living things interact with their environment 2. describes the world

Environmentalism 1. is not ecology 2. conservation of natural resources

AN OVERVIEW OF POPULATION ECOLOGY
Population- a group of individuals of a single species that occupy the same area Student Misconceptions and Concerns 1. Students might imagine that the opportunistic life history is risky and might not be successful over time. Plants such as the agave (century plant) risk all of their reproductive effort on a single life-ending event. However, this reproductive strategy has evolved over time because it has been successful (but like investments, past success does not guarantee future success). 2. Many nonmajors have trouble thinking about the evolution of systems. One analogy that can be developed, especially for economically minded students, makes 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 grew exponentially (or so it seemed!) with few density-dependent factors. Today in the United States, McDonald’s restaurants experience competition with each other and many other fast-food restaurants such as Burger King and Taco Bell. The population of McDonald’s restaurants in the United States has somewhat leveled off 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. Consider comparing opportunistic and equilibrial life histories in a table with the following top headings: Type of Survivorship Curve, Age of Maturity, Number of Offspring, Use of Parental Care, Stability of the Population, Is the Population Density Dependent?, and Examples. 2. Your class might get some practice analyzing life histories by describing additional examples. Challenge your students to classify the type of survivorship curve that would be expected. Frogs and fish typically produce hundreds of eggs, leading to type III survivorship curves. Elephants and whales typically produce few offspring in life histories that more likely represent type I survivorship curves. Mice and other small mammals are capable of producing litters of 10 or more offspring a year, over a several year period. These mammals have life histories that may be intermediate, leading to type II survivorship curves. 3. The following Center for Disease Control web site provides information and life tables for people living in the United States. ( 4. Compromise is a key lesson in biology. No adaptation can be perfect, no reproductive strategy can maximize all types of efforts. As the text notes, an organism cannot have many offspring and great amounts of parental care. Resources, including time, are limited. Have students imagine how their life as parents would change with the birth of quadruplet children.

Population ecology focuses on the factors that influence a population’s
Density Structure Size Growth rate Student Misconceptions and Concerns 1. Students might imagine that the opportunistic life history is risky and might not be successful over time. Plants such as the agave (century plant) risk all of their reproductive effort on a single life-ending event. However, this reproductive strategy has evolved over time because it has been successful (but like investments, past success does not guarantee future success). 2. Many nonmajors have trouble thinking about the evolution of systems. One analogy that can be developed, especially for economically minded students, makes 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 grew exponentially (or so it seemed!) with few density-dependent factors. Today in the United States, McDonald’s restaurants experience competition with each other and many other fast-food restaurants such as Burger King and Taco Bell. The population of McDonald’s restaurants in the United States has somewhat leveled off 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. Consider comparing opportunistic and equilibrial life histories in a table with the following top headings: Type of Survivorship Curve, Age of Maturity, Number of Offspring, Use of Parental Care, Stability of the Population, Is the Population Density Dependent?, and Examples. 2. Your class might get some practice analyzing life histories by describing additional examples. Challenge your students to classify the type of survivorship curve that would be expected. Frogs and fish typically produce hundreds of eggs, leading to type III survivorship curves. Elephants and whales typically produce few offspring in life histories that more likely represent type I survivorship curves. Mice and other small mammals are capable of producing litters of 10 or more offspring a year, over a several year period. These mammals have life histories that may be intermediate, leading to type II survivorship curves. 3. The following Center for Disease Control web site provides information and life tables for people living in the United States. ( 4. Compromise is a key lesson in biology. No adaptation can be perfect, no reproductive strategy can maximize all types of efforts. As the text notes, an organism cannot have many offspring and great amounts of parental care. Resources, including time, are limited. Have students imagine how their life as parents would change with the birth of quadruplet children.

Figure 19.1 An ecologist styding a population of black-browed albatross in the Falkland Islands, east of the tip of South America An ecologist studying a population of black-browed albatross in the Falkland Islands, east of the tip of South America Figure 19.1

Population ecology is used to study
How to develop sustainable fisheries How to control pests and pathogens Human population growth Student Misconceptions and Concerns 1. Students might imagine that the opportunistic life history is risky and might not be successful over time. Plants such as the agave (century plant) risk all of their reproductive effort on a single life-ending event. However, this reproductive strategy has evolved over time because it has been successful (but like investments, past success does not guarantee future success). 2. Many nonmajors have trouble thinking about the evolution of systems. One analogy that can be developed, especially for economically minded students, makes 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 grew exponentially (or so it seemed!) with few density-dependent factors. Today in the United States, McDonald’s restaurants experience competition with each other and many other fast-food restaurants such as Burger King and Taco Bell. The population of McDonald’s restaurants in the United States has somewhat leveled off 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. Consider comparing opportunistic and equilibrial life histories in a table with the following top headings: Type of Survivorship Curve, Age of Maturity, Number of Offspring, Use of Parental Care, Stability of the Population, Is the Population Density Dependent?, and Examples. 2. Your class might get some practice analyzing life histories by describing additional examples. Challenge your students to classify the type of survivorship curve that would be expected. Frogs and fish typically produce hundreds of eggs, leading to type III survivorship curves. Elephants and whales typically produce few offspring in life histories that more likely represent type I survivorship curves. Mice and other small mammals are capable of producing litters of 10 or more offspring a year, over a several year period. These mammals have life histories that may be intermediate, leading to type II survivorship curves. 3. The following Center for Disease Control web site provides information and life tables for people living in the United States. ( 4. Compromise is a key lesson in biology. No adaptation can be perfect, no reproductive strategy can maximize all types of efforts. As the text notes, an organism cannot have many offspring and great amounts of parental care. Resources, including time, are limited. Have students imagine how their life as parents would change with the birth of quadruplet children.

Population Density Population density is the number of individuals of a species per unit of area or volume. Examples include The number of largemouth bass per cubic kilometer (km3) of a lake The number of oak trees per square kilometer (km2) in a forest The number of nematodes per cubic meter (m3) in a forest’s soil Student Misconceptions and Concerns 1. Students might imagine that the opportunistic life history is risky and might not be successful over time. Plants such as the agave (century plant) risk all of their reproductive effort on a single life-ending event. However, this reproductive strategy has evolved over time because it has been successful (but like investments, past success does not guarantee future success). 2. Many nonmajors have trouble thinking about the evolution of systems. One analogy that can be developed, especially for economically minded students, makes 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 grew exponentially (or so it seemed!) with few density-dependent factors. Today in the United States, McDonald’s restaurants experience competition with each other and many other fast-food restaurants such as Burger King and Taco Bell. The population of McDonald’s restaurants in the United States has somewhat leveled off 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. Consider comparing opportunistic and equilibrial life histories in a table with the following top headings: Type of Survivorship Curve, Age of Maturity, Number of Offspring, Use of Parental Care, Stability of the Population, Is the Population Density Dependent?, and Examples. 2. Your class might get some practice analyzing life histories by describing additional examples. Challenge your students to classify the type of survivorship curve that would be expected. Frogs and fish typically produce hundreds of eggs, leading to type III survivorship curves. Elephants and whales typically produce few offspring in life histories that more likely represent type I survivorship curves. Mice and other small mammals are capable of producing litters of 10 or more offspring a year, over a several year period. These mammals have life histories that may be intermediate, leading to type II survivorship curves. 3. The following Center for Disease Control web site provides information and life tables for people living in the United States. ( 4. Compromise is a key lesson in biology. No adaptation can be perfect, no reproductive strategy can maximize all types of efforts. As the text notes, an organism cannot have many offspring and great amounts of parental care. Resources, including time, are limited. Have students imagine how their life as parents would change with the birth of quadruplet children.

How do we measure population density?
In most cases, it is impractical or impossible to count all individuals in a population. In some cases, population densities are estimated by indirect indicators, such as Number of bird nests Rodent burrows Student Misconceptions and Concerns 1. Students might imagine that the opportunistic life history is risky and might not be successful over time. Plants such as the agave (century plant) risk all of their reproductive effort on a single life-ending event. However, this reproductive strategy has evolved over time because it has been successful (but like investments, past success does not guarantee future success). 2. Many nonmajors have trouble thinking about the evolution of systems. One analogy that can be developed, especially for economically minded students, makes 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 grew exponentially (or so it seemed!) with few density-dependent factors. Today in the United States, McDonald’s restaurants experience competition with each other and many other fast-food restaurants such as Burger King and Taco Bell. The population of McDonald’s restaurants in the United States has somewhat leveled off 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. Consider comparing opportunistic and equilibrial life histories in a table with the following top headings: Type of Survivorship Curve, Age of Maturity, Number of Offspring, Use of Parental Care, Stability of the Population, Is the Population Density Dependent?, and Examples. 2. Your class might get some practice analyzing life histories by describing additional examples. Challenge your students to classify the type of survivorship curve that would be expected. Frogs and fish typically produce hundreds of eggs, leading to type III survivorship curves. Elephants and whales typically produce few offspring in life histories that more likely represent type I survivorship curves. Mice and other small mammals are capable of producing litters of 10 or more offspring a year, over a several year period. These mammals have life histories that may be intermediate, leading to type II survivorship curves. 3. The following Center for Disease Control web site provides information and life tables for people living in the United States. ( 4. Compromise is a key lesson in biology. No adaptation can be perfect, no reproductive strategy can maximize all types of efforts. As the text notes, an organism cannot have many offspring and great amounts of parental care. Resources, including time, are limited. Have students imagine how their life as parents would change with the birth of quadruplet children.

Figure 19.2 An indirect census of a prairie dog population

POPULATION GROWTH MODELS
Population size fluctuates as individuals Are born Immigrate into an area Emigrate away Die Student Misconceptions and Concerns 1. Students with limited biology backgrounds may unrealistically expect simplistic explanations. When we consider the factors that limit population size, we learn to appreciate the complex nature of biology. As noted in the text, population growth models are approximations and density dependent and density independent factors are usually both involved to some extent. Teaching Tips 1. Exponential growth of 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. For example, $1000 invested at 7% interest is worth more than $30,000 in 50 years. Consider a short assignment to have students calculate the value of a simple interest-bearing investment over a set period of years, similar to the example just noted. 2. It is typically easier to understand a concept when the examples are familiar. Consider the biology of your region and identify a species that is likely to be well known by your students. Perhaps this will be a squirrel population on your campus. Challenge your class to imagine the changes in this squirrel population if a) a strong storm toppled half the trees on campus or b) a large group of dogs moved onto campus for a few weeks. 3. Consider challenging your class to explain why the lynx and hare cycle does not result in the elimination of one or both of the species. Why don’t we see hare’s hunted to extinction? Students may not have considered the difficulty in finding prey when prey populations are low. This challenge permits a recovery of the hare population, which in turn supports the recovery of the lynx population.

The Exponential Growth Model: The Ideal of an Unlimited Environment
Exponential population growth (J shaped growth curve)- slow growth at first followed by increasingly faster rates of growth describes the expansion of a population in an ideal and unlimited environment. Student Misconceptions and Concerns 1. Students with limited biology backgrounds may unrealistically expect simplistic explanations. When we consider the factors that limit population size, we learn to appreciate the complex nature of biology. As noted in the text, population growth models are approximations and density dependent and density independent factors are usually both involved to some extent. Teaching Tips 1. Exponential growth of 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. For example, $1000 invested at 7% interest is worth more than $30,000 in 50 years. Consider a short assignment to have students calculate the value of a simple interest-bearing investment over a set period of years, similar to the example just noted. 2. It is typically easier to understand a concept when the examples are familiar. Consider the biology of your region and identify a species that is likely to be well known by your students. Perhaps this will be a squirrel population on your campus. Challenge your class to imagine the changes in this squirrel population if a) a strong storm toppled half the trees on campus or b) a large group of dogs moved onto campus for a few weeks. 3. Consider challenging your class to explain why the lynx and hare cycle does not result in the elimination of one or both of the species. Why don’t we see hare’s hunted to extinction? Students may not have considered the difficulty in finding prey when prey populations are low. This challenge permits a recovery of the hare population, which in turn supports the recovery of the lynx population. © 2010 Pearson Education, Inc.

Population size (N) Time (months) 500 450 400 350 300 250 200 150 100
Figure 19.5 Exponential growth of a rabbit population 50 1 2 3 4 5 6 7 8 9 10 11 12 Time (months) Figure 19.5

Figure 19.5a Exponential growth of a rabbit population

Exponential growth explains how
A few dozen rabbits can multiple into millions In certain circumstances following disasters, organisms that have opportunistic life history patterns can rapidly recolonize a habitat Student Misconceptions and Concerns 1. Students with limited biology backgrounds may unrealistically expect simplistic explanations. When we consider the factors that limit population size, we learn to appreciate the complex nature of biology. As noted in the text, population growth models are approximations and density dependent and density independent factors are usually both involved to some extent. Teaching Tips 1. Exponential growth of 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. For example, $1000 invested at 7% interest is worth more than $30,000 in 50 years. Consider a short assignment to have students calculate the value of a simple interest-bearing investment over a set period of years, similar to the example just noted. 2. It is typically easier to understand a concept when the examples are familiar. Consider the biology of your region and identify a species that is likely to be well known by your students. Perhaps this will be a squirrel population on your campus. Challenge your class to imagine the changes in this squirrel population if a) a strong storm toppled half the trees on campus or b) a large group of dogs moved onto campus for a few weeks. 3. Consider challenging your class to explain why the lynx and hare cycle does not result in the elimination of one or both of the species. Why don’t we see hare’s hunted to extinction? Students may not have considered the difficulty in finding prey when prey populations are low. This challenge permits a recovery of the hare population, which in turn supports the recovery of the lynx population.

Table 36.4A Exponential Growth of Rabbits, r = 0.3.

The Logistic Growth Model: The Reality of a Limited Environment
Limiting factors environmental factors that hold population growth in check restrict the number of individuals that can occupy a habitat Student Misconceptions and Concerns 1. Students with limited biology backgrounds may unrealistically expect simplistic explanations. When we consider the factors that limit population size, we learn to appreciate the complex nature of biology. As noted in the text, population growth models are approximations and density dependent and density independent factors are usually both involved to some extent. Teaching Tips 1. Exponential growth of 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. For example, $1000 invested at 7% interest is worth more than $30,000 in 50 years. Consider a short assignment to have students calculate the value of a simple interest-bearing investment over a set period of years, similar to the example just noted. 2. It is typically easier to understand a concept when the examples are familiar. Consider the biology of your region and identify a species that is likely to be well known by your students. Perhaps this will be a squirrel population on your campus. Challenge your class to imagine the changes in this squirrel population if a) a strong storm toppled half the trees on campus or b) a large group of dogs moved onto campus for a few weeks. 3. Consider challenging your class to explain why the lynx and hare cycle does not result in the elimination of one or both of the species. Why don’t we see hare’s hunted to extinction? Students may not have considered the difficulty in finding prey when prey populations are low. This challenge permits a recovery of the hare population, which in turn supports the recovery of the lynx population. © 2010 Pearson Education, Inc.

carrying capacity- maximum population size that can be sustained in an area
Student Misconceptions and Concerns 1. Students with limited biology backgrounds may unrealistically expect simplistic explanations. When we consider the factors that limit population size, we learn to appreciate the complex nature of biology. As noted in the text, population growth models are approximations and density dependent and density independent factors are usually both involved to some extent. Teaching Tips 1. Exponential growth of 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. For example, $1000 invested at 7% interest is worth more than $30,000 in 50 years. Consider a short assignment to have students calculate the value of a simple interest-bearing investment over a set period of years, similar to the example just noted. 2. It is typically easier to understand a concept when the examples are familiar. Consider the biology of your region and identify a species that is likely to be well known by your students. Perhaps this will be a squirrel population on your campus. Challenge your class to imagine the changes in this squirrel population if a) a strong storm toppled half the trees on campus or b) a large group of dogs moved onto campus for a few weeks. 3. Consider challenging your class to explain why the lynx and hare cycle does not result in the elimination of one or both of the species. Why don’t we see hare’s hunted to extinction? Students may not have considered the difficulty in finding prey when prey populations are low. This challenge permits a recovery of the hare population, which in turn supports the recovery of the lynx population.

logistic population growth (S shaped growth curve)- growth rate decreases as the population size approaches carrying capacity Student Misconceptions and Concerns 1. Students with limited biology backgrounds may unrealistically expect simplistic explanations. When we consider the factors that limit population size, we learn to appreciate the complex nature of biology. As noted in the text, population growth models are approximations and density dependent and density independent factors are usually both involved to some extent. Teaching Tips 1. Exponential growth of 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. For example, $1000 invested at 7% interest is worth more than $30,000 in 50 years. Consider a short assignment to have students calculate the value of a simple interest-bearing investment over a set period of years, similar to the example just noted. 2. It is typically easier to understand a concept when the examples are familiar. Consider the biology of your region and identify a species that is likely to be well known by your students. Perhaps this will be a squirrel population on your campus. Challenge your class to imagine the changes in this squirrel population if a) a strong storm toppled half the trees on campus or b) a large group of dogs moved onto campus for a few weeks. 3. Consider challenging your class to explain why the lynx and hare cycle does not result in the elimination of one or both of the species. Why don’t we see hare’s hunted to extinction? Students may not have considered the difficulty in finding prey when prey populations are low. This challenge permits a recovery of the hare population, which in turn supports the recovery of the lynx population.

Figure 36.4B Growth of a population of fur seals.

Breeding male fur seals
10 8 Breeding male fur seals (thousands) 6 4 2 Figure 36.4B Growth of a population of fur seals. 1915 1925 1935 1945 Year

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.

Table 36.4B Effect of K on Growth Rate as N Approaches K, K = 1,000, r = 0.1.

The carrying capacity for a population varies, depending on
The species The resources available in the habitat Student Misconceptions and Concerns 1. Students with limited biology backgrounds may unrealistically expect simplistic explanations. When we consider the factors that limit population size, we learn to appreciate the complex nature of biology. As noted in the text, population growth models are approximations and density dependent and density independent factors are usually both involved to some extent. Teaching Tips 1. Exponential growth of 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. For example, $1000 invested at 7% interest is worth more than $30,000 in 50 years. Consider a short assignment to have students calculate the value of a simple interest-bearing investment over a set period of years, similar to the example just noted. 2. It is typically easier to understand a concept when the examples are familiar. Consider the biology of your region and identify a species that is likely to be well known by your students. Perhaps this will be a squirrel population on your campus. Challenge your class to imagine the changes in this squirrel population if a) a strong storm toppled half the trees on campus or b) a large group of dogs moved onto campus for a few weeks. 3. Consider challenging your class to explain why the lynx and hare cycle does not result in the elimination of one or both of the species. Why don’t we see hare’s hunted to extinction? Students may not have considered the difficulty in finding prey when prey populations are low. This challenge permits a recovery of the hare population, which in turn supports the recovery of the lynx population.

Organisms exhibiting equilibrial life history patterns occur in environments where the population size is at or near carrying capacity. Student Misconceptions and Concerns 1. Students with limited biology backgrounds may unrealistically expect simplistic explanations. When we consider the factors that limit population size, we learn to appreciate the complex nature of biology. As noted in the text, population growth models are approximations and density dependent and density independent factors are usually both involved to some extent. Teaching Tips 1. Exponential growth of 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. For example, $1000 invested at 7% interest is worth more than $30,000 in 50 years. Consider a short assignment to have students calculate the value of a simple interest-bearing investment over a set period of years, similar to the example just noted. 2. It is typically easier to understand a concept when the examples are familiar. Consider the biology of your region and identify a species that is likely to be well known by your students. Perhaps this will be a squirrel population on your campus. Challenge your class to imagine the changes in this squirrel population if a) a strong storm toppled half the trees on campus or b) a large group of dogs moved onto campus for a few weeks. 3. Consider challenging your class to explain why the lynx and hare cycle does not result in the elimination of one or both of the species. Why don’t we see hare’s hunted to extinction? Students may not have considered the difficulty in finding prey when prey populations are low. This challenge permits a recovery of the hare population, which in turn supports the recovery of the lynx population.

No natural population fits either one perfectly.
The logistic model and the exponential model are theoretical ideals of population growth. No natural population fits either one perfectly. Student Misconceptions and Concerns 1. Students with limited biology backgrounds may unrealistically expect simplistic explanations. When we consider the factors that limit population size, we learn to appreciate the complex nature of biology. As noted in the text, population growth models are approximations and density dependent and density independent factors are usually both involved to some extent. Teaching Tips 1. Exponential growth of 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. For example, $1000 invested at 7% interest is worth more than $30,000 in 50 years. Consider a short assignment to have students calculate the value of a simple interest-bearing investment over a set period of years, similar to the example just noted. 2. It is typically easier to understand a concept when the examples are familiar. Consider the biology of your region and identify a species that is likely to be well known by your students. Perhaps this will be a squirrel population on your campus. Challenge your class to imagine the changes in this squirrel population if a) a strong storm toppled half the trees on campus or b) a large group of dogs moved onto campus for a few weeks. 3. Consider challenging your class to explain why the lynx and hare cycle does not result in the elimination of one or both of the species. Why don’t we see hare’s hunted to extinction? Students may not have considered the difficulty in finding prey when prey populations are low. This challenge permits a recovery of the hare population, which in turn supports the recovery of the lynx population.

Exponential growth Number of individuals Carrying capacity
Logistic growth Figure 19.7 Comparison of exponential and logistic growth Time Figure 19.7

opportunistic life history take advantage of favorable conditions
small, short lived organisms Student Misconceptions and Concerns 1. Students might imagine that the opportunistic life history is risky and might not be successful over time. Plants such as the agave (century plant) risk all of their reproductive effort on a single life-ending event. However, this reproductive strategy has evolved over time because it has been successful (but like investments, past success does not guarantee future success). 2. Many nonmajors have trouble thinking about the evolution of systems. One analogy that can be developed, especially for economically minded students, makes 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 grew exponentially (or so it seemed!) with few density-dependent factors. Today in the United States, McDonald’s restaurants experience competition with each other and many other fast-food restaurants such as Burger King and Taco Bell. The population of McDonald’s restaurants in the United States has somewhat leveled off 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. Consider comparing opportunistic and equilibrial life histories in a table with the following top headings: Type of Survivorship Curve, Age of Maturity, Number of Offspring, Use of Parental Care, Stability of the Population, Is the Population Density Dependent?, and Examples. 2. Your class might get some practice analyzing life histories by describing additional examples. Challenge your students to classify the type of survivorship curve that would be expected. Frogs and fish typically produce hundreds of eggs, leading to type III survivorship curves. Elephants and whales typically produce few offspring in life histories that more likely represent type I survivorship curves. Mice and other small mammals are capable of producing litters of 10 or more offspring a year, over a several year period. These mammals have life histories that may be intermediate, leading to type II survivorship curves. 3. The following Center for Disease Control web site provides information and life tables for people living in the United States. ( 4. Compromise is a key lesson in biology. No adaptation can be perfect, no reproductive strategy can maximize all types of efforts. As the text notes, an organism cannot have many offspring and great amounts of parental care. Resources, including time, are limited. Have students imagine how their life as parents would change with the birth of quadruplet children.

Dandelions have an opportunistic life history
Table 19.2a Some Life History Characteristics of Opportunistic and Equilibrial Populations Dandelions have an opportunistic life history Table 19.2a

equilibrial life history reach sexual maturity slowly
produce few, well cared for offspring larger, longer lived organisms Student Misconceptions and Concerns 1. Students might imagine that the opportunistic life history is risky and might not be successful over time. Plants such as the agave (century plant) risk all of their reproductive effort on a single life-ending event. However, this reproductive strategy has evolved over time because it has been successful (but like investments, past success does not guarantee future success). 2. Many nonmajors have trouble thinking about the evolution of systems. One analogy that can be developed, especially for economically minded students, makes 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 grew exponentially (or so it seemed!) with few density-dependent factors. Today in the United States, McDonald’s restaurants experience competition with each other and many other fast-food restaurants such as Burger King and Taco Bell. The population of McDonald’s restaurants in the United States has somewhat leveled off 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. Consider comparing opportunistic and equilibrial life histories in a table with the following top headings: Type of Survivorship Curve, Age of Maturity, Number of Offspring, Use of Parental Care, Stability of the Population, Is the Population Density Dependent?, and Examples. 2. Your class might get some practice analyzing life histories by describing additional examples. Challenge your students to classify the type of survivorship curve that would be expected. Frogs and fish typically produce hundreds of eggs, leading to type III survivorship curves. Elephants and whales typically produce few offspring in life histories that more likely represent type I survivorship curves. Mice and other small mammals are capable of producing litters of 10 or more offspring a year, over a several year period. These mammals have life histories that may be intermediate, leading to type II survivorship curves. 3. The following Center for Disease Control web site provides information and life tables for people living in the United States. ( 4. Compromise is a key lesson in biology. No adaptation can be perfect, no reproductive strategy can maximize all types of efforts. As the text notes, an organism cannot have many offspring and great amounts of parental care. Resources, including time, are limited. Have students imagine how their life as parents would change with the birth of quadruplet children.

Elephants have an equilibrial life history
Table 19.2b Some Life History Characteristics of Opportunistic and Equilibrial Populations Elephants have an equilibrial life history Table 19.2b

Table 19.2 Some Life History Characteristics of Opportunistic and Equilibrial Populations

Regulation of Population Growth Density-Dependent Factors
The logistic model is a description of interspecific competition. interspecific competition- competition between individuals of the same species for the same limited resources Student Misconceptions and Concerns 1. Students with limited biology backgrounds may unrealistically expect simplistic explanations. When we consider the factors that limit population size, we learn to appreciate the complex nature of biology. As noted in the text, population growth models are approximations and density dependent and density independent factors are usually both involved to some extent. Teaching Tips 1. Exponential growth of 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. For example, $1000 invested at 7% interest is worth more than $30,000 in 50 years. Consider a short assignment to have students calculate the value of a simple interest-bearing investment over a set period of years, similar to the example just noted. 2. It is typically easier to understand a concept when the examples are familiar. Consider the biology of your region and identify a species that is likely to be well known by your students. Perhaps this will be a squirrel population on your campus. Challenge your class to imagine the changes in this squirrel population if a) a strong storm toppled half the trees on campus or b) a large group of dogs moved onto campus for a few weeks. 3. Consider challenging your class to explain why the lynx and hare cycle does not result in the elimination of one or both of the species. Why don’t we see hare’s hunted to extinction? Students may not have considered the difficulty in finding prey when prey populations are low. This challenge permits a recovery of the hare population, which in turn supports the recovery of the lynx population. © 2010 Pearson Education, Inc.

As population size increases Competition becomes more intense
The growth rate declines in proportion to the intensity of competition Student Misconceptions and Concerns 1. Students with limited biology backgrounds may unrealistically expect simplistic explanations. When we consider the factors that limit population size, we learn to appreciate the complex nature of biology. As noted in the text, population growth models are approximations and density dependent and density independent factors are usually both involved to some extent. Teaching Tips 1. Exponential growth of 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. For example, $1000 invested at 7% interest is worth more than $30,000 in 50 years. Consider a short assignment to have students calculate the value of a simple interest-bearing investment over a set period of years, similar to the example just noted. 2. It is typically easier to understand a concept when the examples are familiar. Consider the biology of your region and identify a species that is likely to be well known by your students. Perhaps this will be a squirrel population on your campus. Challenge your class to imagine the changes in this squirrel population if a) a strong storm toppled half the trees on campus or b) a large group of dogs moved onto campus for a few weeks. 3. Consider challenging your class to explain why the lynx and hare cycle does not result in the elimination of one or both of the species. Why don’t we see hare’s hunted to extinction? Students may not have considered the difficulty in finding prey when prey populations are low. This challenge permits a recovery of the hare population, which in turn supports the recovery of the lynx population.

density-dependent factor- a population-limiting factor whose effects intensify as the population increases in density Student Misconceptions and Concerns 1. Students with limited biology backgrounds may unrealistically expect simplistic explanations. When we consider the factors that limit population size, we learn to appreciate the complex nature of biology. As noted in the text, population growth models are approximations and density dependent and density independent factors are usually both involved to some extent. Teaching Tips 1. Exponential growth of 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. For example, $1000 invested at 7% interest is worth more than $30,000 in 50 years. Consider a short assignment to have students calculate the value of a simple interest-bearing investment over a set period of years, similar to the example just noted. 2. It is typically easier to understand a concept when the examples are familiar. Consider the biology of your region and identify a species that is likely to be well known by your students. Perhaps this will be a squirrel population on your campus. Challenge your class to imagine the changes in this squirrel population if a) a strong storm toppled half the trees on campus or b) a large group of dogs moved onto campus for a few weeks. 3. Consider challenging your class to explain why the lynx and hare cycle does not result in the elimination of one or both of the species. Why don’t we see hare’s hunted to extinction? Students may not have considered the difficulty in finding prey when prey populations are low. This challenge permits a recovery of the hare population, which in turn supports the recovery of the lynx population.

Number of breeding pairs
12 11 10 Average clutch size 9 8 Figure 19.8a Density-dependent regulation of population growth 10 20 30 40 50 60 70 80 90 Number of breeding pairs (a) Decreasing birth rate with increasing density in a population of great tits Figure 19.8a

Density (beetles/0.5 g flour)
100 80 60 Survivors (%) 40 20 Figure 19.8b Density-dependent regulation of population growth 20 40 60 80 100 120 Density (beetles/0.5 g flour) (b) Decreasing survival rates with increasing density in a population of flour beetles Figure 19.8b

Density-dependent factors
1. Accumulation of toxic wastes 2. Limited food supply 3. Limited territory Student Misconceptions and Concerns 1. Students with limited biology backgrounds may unrealistically expect simplistic explanations. When we consider the factors that limit population size, we learn to appreciate the complex nature of biology. As noted in the text, population growth models are approximations and density dependent and density independent factors are usually both involved to some extent. Teaching Tips 1. Exponential growth of 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. For example, $1000 invested at 7% interest is worth more than $30,000 in 50 years. Consider a short assignment to have students calculate the value of a simple interest-bearing investment over a set period of years, similar to the example just noted. 2. It is typically easier to understand a concept when the examples are familiar. Consider the biology of your region and identify a species that is likely to be well known by your students. Perhaps this will be a squirrel population on your campus. Challenge your class to imagine the changes in this squirrel population if a) a strong storm toppled half the trees on campus or b) a large group of dogs moved onto campus for a few weeks. 3. Consider challenging your class to explain why the lynx and hare cycle does not result in the elimination of one or both of the species. Why don’t we see hare’s hunted to extinction? Students may not have considered the difficulty in finding prey when prey populations are low. This challenge permits a recovery of the hare population, which in turn supports the recovery of the lynx population.

Figure 19.9 Space as a limiting resource in a population of gannets

Density-Independent Factors
1. population-limiting factors whose intensity is unrelated to population density 2. abiotic factors: fires, floods, storms Student Misconceptions and Concerns 1. Students with limited biology backgrounds may unrealistically expect simplistic explanations. When we consider the factors that limit population size, we learn to appreciate the complex nature of biology. As noted in the text, population growth models are approximations and density dependent and density independent factors are usually both involved to some extent. Teaching Tips 1. Exponential growth of 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. For example, $1000 invested at 7% interest is worth more than $30,000 in 50 years. Consider a short assignment to have students calculate the value of a simple interest-bearing investment over a set period of years, similar to the example just noted. 2. It is typically easier to understand a concept when the examples are familiar. Consider the biology of your region and identify a species that is likely to be well known by your students. Perhaps this will be a squirrel population on your campus. Challenge your class to imagine the changes in this squirrel population if a) a strong storm toppled half the trees on campus or b) a large group of dogs moved onto campus for a few weeks. 3. Consider challenging your class to explain why the lynx and hare cycle does not result in the elimination of one or both of the species. Why don’t we see hare’s hunted to extinction? Students may not have considered the difficulty in finding prey when prey populations are low. This challenge permits a recovery of the hare population, which in turn supports the recovery of the lynx population.

Exponential growth Sudden decline Number of aphids Figure Weather change as a density-independent factor limiting growth of an aphid population Apr May Jun Jul Aug Sep Oct Nov Dec Weather change as a density-independent factor limiting growth of an aphid population Figure 19.10

Density-independent factors Density-dependent factors
In many natural populations, density-independent factors limit population size before density-dependent factors become important. Over the long term, most populations are probably regulated by a mixture of Density-independent factors Density-dependent factors Student Misconceptions and Concerns 1. Students with limited biology backgrounds may unrealistically expect simplistic explanations. When we consider the factors that limit population size, we learn to appreciate the complex nature of biology. As noted in the text, population growth models are approximations and density dependent and density independent factors are usually both involved to some extent. Teaching Tips 1. Exponential growth of 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. For example, $1000 invested at 7% interest is worth more than $30,000 in 50 years. Consider a short assignment to have students calculate the value of a simple interest-bearing investment over a set period of years, similar to the example just noted. 2. It is typically easier to understand a concept when the examples are familiar. Consider the biology of your region and identify a species that is likely to be well known by your students. Perhaps this will be a squirrel population on your campus. Challenge your class to imagine the changes in this squirrel population if a) a strong storm toppled half the trees on campus or b) a large group of dogs moved onto campus for a few weeks. 3. Consider challenging your class to explain why the lynx and hare cycle does not result in the elimination of one or both of the species. Why don’t we see hare’s hunted to extinction? Students may not have considered the difficulty in finding prey when prey populations are low. This challenge permits a recovery of the hare population, which in turn supports the recovery of the lynx population.

Population Cycles Some populations have regular boom-and-bust cycles characterized by periods of rapid growth followed by steep population declines. Student Misconceptions and Concerns 1. Students with limited biology backgrounds may unrealistically expect simplistic explanations. When we consider the factors that limit population size, we learn to appreciate the complex nature of biology. As noted in the text, population growth models are approximations and density dependent and density independent factors are usually both involved to some extent. Teaching Tips 1. Exponential growth of 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. For example, $1000 invested at 7% interest is worth more than $30,000 in 50 years. Consider a short assignment to have students calculate the value of a simple interest-bearing investment over a set period of years, similar to the example just noted. 2. It is typically easier to understand a concept when the examples are familiar. Consider the biology of your region and identify a species that is likely to be well known by your students. Perhaps this will be a squirrel population on your campus. Challenge your class to imagine the changes in this squirrel population if a) a strong storm toppled half the trees on campus or b) a large group of dogs moved onto campus for a few weeks. 3. Consider challenging your class to explain why the lynx and hare cycle does not result in the elimination of one or both of the species. Why don’t we see hare’s hunted to extinction? Students may not have considered the difficulty in finding prey when prey populations are low. This challenge permits a recovery of the hare population, which in turn supports the recovery of the lynx population.

A well studied example of boom and bust cycles are the cycles of
Snowshoe hares One of the hares’ predators, the lynx Student Misconceptions and Concerns 1. Students with limited biology backgrounds may unrealistically expect simplistic explanations. When we consider the factors that limit population size, we learn to appreciate the complex nature of biology. As noted in the text, population growth models are approximations and density dependent and density independent factors are usually both involved to some extent. Teaching Tips 1. Exponential growth of 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. For example, $1000 invested at 7% interest is worth more than $30,000 in 50 years. Consider a short assignment to have students calculate the value of a simple interest-bearing investment over a set period of years, similar to the example just noted. 2. It is typically easier to understand a concept when the examples are familiar. Consider the biology of your region and identify a species that is likely to be well known by your students. Perhaps this will be a squirrel population on your campus. Challenge your class to imagine the changes in this squirrel population if a) a strong storm toppled half the trees on campus or b) a large group of dogs moved onto campus for a few weeks. 3. Consider challenging your class to explain why the lynx and hare cycle does not result in the elimination of one or both of the species. Why don’t we see hare’s hunted to extinction? Students may not have considered the difficulty in finding prey when prey populations are low. This challenge permits a recovery of the hare population, which in turn supports the recovery of the lynx population.

Figure 19.11 Snowshoe hare Lynx Hare population (thousands)
160 Hare population (thousands) Lynx population (thousands) 120 9 80 6 40 3 1850 1900 Year Figure Population cycles of the snowshoe hare and the lynx Figure 19.11

The cause of these hare and lynx cycles may be
Winter food shortages for the hares Overexploitation of hares by lynx A combination of both of these mechanisms Student Misconceptions and Concerns 1. Students with limited biology backgrounds may unrealistically expect simplistic explanations. When we consider the factors that limit population size, we learn to appreciate the complex nature of biology. As noted in the text, population growth models are approximations and density dependent and density independent factors are usually both involved to some extent. Teaching Tips 1. Exponential growth of 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. For example, $1000 invested at 7% interest is worth more than $30,000 in 50 years. Consider a short assignment to have students calculate the value of a simple interest-bearing investment over a set period of years, similar to the example just noted. 2. It is typically easier to understand a concept when the examples are familiar. Consider the biology of your region and identify a species that is likely to be well known by your students. Perhaps this will be a squirrel population on your campus. Challenge your class to imagine the changes in this squirrel population if a) a strong storm toppled half the trees on campus or b) a large group of dogs moved onto campus for a few weeks. 3. Consider challenging your class to explain why the lynx and hare cycle does not result in the elimination of one or both of the species. Why don’t we see hare’s hunted to extinction? Students may not have considered the difficulty in finding prey when prey populations are low. This challenge permits a recovery of the hare population, which in turn supports the recovery of the lynx population.

APPLICATIONS OF POPULATION ECOLOGY
Population ecology is used to Increase populations of organisms we wish to harvest Decrease populations of pests Save populations of organisms threatened with extinction Student Misconceptions and Concerns 1. Most students do not understand the dangers of relocating wildlife or letting their pet loose in a park or non-native environment. As noted in the text, the consequences of accidental or deliberate introductions costs the United States more than $130 billion a year. What might seem like a kind gesture to your students is a very dangerous activity, little understood by the public. 2. The history of the widespread abuse of pesticides in North America occurred before most of your students were born. Yet, the lessons of this recent history remind us of the potential consequences. Rachel Carson’s book Silent Spring, or passages from it, might be a good assignment for your class. Teaching Tips 1. Students are likely to expect that spraying insecticides or using various killing devices (such as bug zappers) will make a significant impact in a pest population. However, many pesticides kill pests and their predators. Further, most pest populations are capable of recovering quickly, perhaps faster than their predators. The complexity of life histories and population dynamics help to illustrate the complexities inherent to biological systems and the unexpected consequences. 2. Coevolution is illustrated by organisms that exhibit reciprocal evolutionary adaptations. Challenge students to explain how rewarding a pollinator with nectar has benefited some plants. Why would plants that have adaptations for only certain pollinators have an advantage? In many cases, pollinators that are restricted to certain species are more likely to transport pollen between members of that species, instead of wasting pollen by taking it to different species. 3. The United States Department of Agriculture sponsors the National Invasive Species Information Center, which has a web site at ( 4. Consider a class assignment to explore the collapse of the northern cod fishery and to identify other fish species in danger of over harvesting. Shark populations may be experiencing such a decline. As emphasized in the text, harvesting a population down to intermediate levels maximizes the sustained yield.

Conservation of Endangered Species
The U.S. Endangered Species Act defines endangered species- species that is in danger of extinction threatened species- species that is likely to become endangered Student Misconceptions and Concerns 1. Most students do not understand the dangers of relocating wildlife or letting their pet loose in a park or non-native environment. As noted in the text, the consequences of accidental or deliberate introductions costs the United States more than $130 billion a year. What might seem like a kind gesture to your students is a very dangerous activity, little understood by the public. 2. The history of the widespread abuse of pesticides in North America occurred before most of your students were born. Yet, the lessons of this recent history remind us of the potential consequences. Rachel Carson’s book Silent Spring, or passages from it, might be a good assignment for your class. Teaching Tips 1. Students are likely to expect that spraying insecticides or using various killing devices (such as bug zappers) will make a significant impact in a pest population. However, many pesticides kill pests and their predators. Further, most pest populations are capable of recovering quickly, perhaps faster than their predators. The complexity of life histories and population dynamics help to illustrate the complexities inherent to biological systems and the unexpected consequences. 2. Coevolution is illustrated by organisms that exhibit reciprocal evolutionary adaptations. Challenge students to explain how rewarding a pollinator with nectar has benefited some plants. Why would plants that have adaptations for only certain pollinators have an advantage? In many cases, pollinators that are restricted to certain species are more likely to transport pollen between members of that species, instead of wasting pollen by taking it to different species. 3. The United States Department of Agriculture sponsors the National Invasive Species Information Center, which has a web site at ( 4. Consider a class assignment to explore the collapse of the northern cod fishery and to identify other fish species in danger of over harvesting. Shark populations may be experiencing such a decline. As emphasized in the text, harvesting a population down to intermediate levels maximizes the sustained yield.

A major factor in population decline is habitat destruction or modification.
Student Misconceptions and Concerns 1. Most students do not understand the dangers of relocating wildlife or letting their pet loose in a park or non-native environment. As noted in the text, the consequences of accidental or deliberate introductions costs the United States more than $130 billion a year. What might seem like a kind gesture to your students is a very dangerous activity, little understood by the public. 2. The history of the widespread abuse of pesticides in North America occurred before most of your students were born. Yet, the lessons of this recent history remind us of the potential consequences. Rachel Carson’s book Silent Spring, or passages from it, might be a good assignment for your class. Teaching Tips 1. Students are likely to expect that spraying insecticides or using various killing devices (such as bug zappers) will make a significant impact in a pest population. However, many pesticides kill pests and their predators. Further, most pest populations are capable of recovering quickly, perhaps faster than their predators. The complexity of life histories and population dynamics help to illustrate the complexities inherent to biological systems and the unexpected consequences. 2. Coevolution is illustrated by organisms that exhibit reciprocal evolutionary adaptations. Challenge students to explain how rewarding a pollinator with nectar has benefited some plants. Why would plants that have adaptations for only certain pollinators have an advantage? In many cases, pollinators that are restricted to certain species are more likely to transport pollen between members of that species, instead of wasting pollen by taking it to different species. 3. The United States Department of Agriculture sponsors the National Invasive Species Information Center, which has a web site at ( 4. Consider a class assignment to explore the collapse of the northern cod fishery and to identify other fish species in danger of over harvesting. Shark populations may be experiencing such a decline. As emphasized in the text, harvesting a population down to intermediate levels maximizes the sustained yield.

The red-cockaded woodpecker
Requires longleaf pine forests with clear flight paths between trees Suffered from fire suppression, increasing the height of the vegetation on the forest floor Recovered from near-extinction to sustainable populations due to controlled burning and other management methods Student Misconceptions and Concerns 1. Most students do not understand the dangers of relocating wildlife or letting their pet loose in a park or non-native environment. As noted in the text, the consequences of accidental or deliberate introductions costs the United States more than $130 billion a year. What might seem like a kind gesture to your students is a very dangerous activity, little understood by the public. 2. The history of the widespread abuse of pesticides in North America occurred before most of your students were born. Yet, the lessons of this recent history remind us of the potential consequences. Rachel Carson’s book Silent Spring, or passages from it, might be a good assignment for your class. Teaching Tips 1. Students are likely to expect that spraying insecticides or using various killing devices (such as bug zappers) will make a significant impact in a pest population. However, many pesticides kill pests and their predators. Further, most pest populations are capable of recovering quickly, perhaps faster than their predators. The complexity of life histories and population dynamics help to illustrate the complexities inherent to biological systems and the unexpected consequences. 2. Coevolution is illustrated by organisms that exhibit reciprocal evolutionary adaptations. Challenge students to explain how rewarding a pollinator with nectar has benefited some plants. Why would plants that have adaptations for only certain pollinators have an advantage? In many cases, pollinators that are restricted to certain species are more likely to transport pollen between members of that species, instead of wasting pollen by taking it to different species. 3. The United States Department of Agriculture sponsors the National Invasive Species Information Center, which has a web site at ( 4. Consider a class assignment to explore the collapse of the northern cod fishery and to identify other fish species in danger of over harvesting. Shark populations may be experiencing such a decline. As emphasized in the text, harvesting a population down to intermediate levels maximizes the sustained yield.

Figure 19.12 A red-cockaded woodpecker perches at the entrance to its
nest in a long-leaf pine tree. High, dense undergrowth impedes the woodpeckers’ access to feeding grounds. Low undergrowth offers birds a clear flight path between nest sites and feeding grounds. Figure Habitat of the red-cockaded woodpecker Figure 19.12

Invasive Species invasive species
a non-native species that has spread far beyond the original point of introduction Causes environmental or economic damage by colonizing and dominating suitable habitats In the United States, invasive species cost about $137 billion a year. Student Misconceptions and Concerns 1. Most students do not understand the dangers of relocating wildlife or letting their pet loose in a park or non-native environment. As noted in the text, the consequences of accidental or deliberate introductions costs the United States more than $130 billion a year. What might seem like a kind gesture to your students is a very dangerous activity, little understood by the public. 2. The history of the widespread abuse of pesticides in North America occurred before most of your students were born. Yet, the lessons of this recent history remind us of the potential consequences. Rachel Carson’s book Silent Spring, or passages from it, might be a good assignment for your class. Teaching Tips 1. Students are likely to expect that spraying insecticides or using various killing devices (such as bug zappers) will make a significant impact in a pest population. However, many pesticides kill pests and their predators. Further, most pest populations are capable of recovering quickly, perhaps faster than their predators. The complexity of life histories and population dynamics help to illustrate the complexities inherent to biological systems and the unexpected consequences. 2. Coevolution is illustrated by organisms that exhibit reciprocal evolutionary adaptations. Challenge students to explain how rewarding a pollinator with nectar has benefited some plants. Why would plants that have adaptations for only certain pollinators have an advantage? In many cases, pollinators that are restricted to certain species are more likely to transport pollen between members of that species, instead of wasting pollen by taking it to different species. 3. The United States Department of Agriculture sponsors the National Invasive Species Information Center, which has a web site at ( 4. Consider a class assignment to explore the collapse of the northern cod fishery and to identify other fish species in danger of over harvesting. Shark populations may be experiencing such a decline. As emphasized in the text, harvesting a population down to intermediate levels maximizes the sustained yield.

Invasive species typically exhibit an opportunistic life history pattern.
Student Misconceptions and Concerns 1. Most students do not understand the dangers of relocating wildlife or letting their pet loose in a park or non-native environment. As noted in the text, the consequences of accidental or deliberate introductions costs the United States more than $130 billion a year. What might seem like a kind gesture to your students is a very dangerous activity, little understood by the public. 2. The history of the widespread abuse of pesticides in North America occurred before most of your students were born. Yet, the lessons of this recent history remind us of the potential consequences. Rachel Carson’s book Silent Spring, or passages from it, might be a good assignment for your class. Teaching Tips 1. Students are likely to expect that spraying insecticides or using various killing devices (such as bug zappers) will make a significant impact in a pest population. However, many pesticides kill pests and their predators. Further, most pest populations are capable of recovering quickly, perhaps faster than their predators. The complexity of life histories and population dynamics help to illustrate the complexities inherent to biological systems and the unexpected consequences. 2. Coevolution is illustrated by organisms that exhibit reciprocal evolutionary adaptations. Challenge students to explain how rewarding a pollinator with nectar has benefited some plants. Why would plants that have adaptations for only certain pollinators have an advantage? In many cases, pollinators that are restricted to certain species are more likely to transport pollen between members of that species, instead of wasting pollen by taking it to different species. 3. The United States Department of Agriculture sponsors the National Invasive Species Information Center, which has a web site at ( 4. Consider a class assignment to explore the collapse of the northern cod fishery and to identify other fish species in danger of over harvesting. Shark populations may be experiencing such a decline. As emphasized in the text, harvesting a population down to intermediate levels maximizes the sustained yield.

Is an invasive species in the western United States
Cheatgrass Is an invasive species in the western United States Currently covers more than 60 million acres of rangeland formerly dominated by native grasses and sagebrush Produces seeds earlier and in greater abundance than native species Forms highly flammable brush creating fires that native plants cannot tolerate Student Misconceptions and Concerns 1. Most students do not understand the dangers of relocating wildlife or letting their pet loose in a park or non-native environment. As noted in the text, the consequences of accidental or deliberate introductions costs the United States more than $130 billion a year. What might seem like a kind gesture to your students is a very dangerous activity, little understood by the public. 2. The history of the widespread abuse of pesticides in North America occurred before most of your students were born. Yet, the lessons of this recent history remind us of the potential consequences. Rachel Carson’s book Silent Spring, or passages from it, might be a good assignment for your class. Teaching Tips 1. Students are likely to expect that spraying insecticides or using various killing devices (such as bug zappers) will make a significant impact in a pest population. However, many pesticides kill pests and their predators. Further, most pest populations are capable of recovering quickly, perhaps faster than their predators. The complexity of life histories and population dynamics help to illustrate the complexities inherent to biological systems and the unexpected consequences. 2. Coevolution is illustrated by organisms that exhibit reciprocal evolutionary adaptations. Challenge students to explain how rewarding a pollinator with nectar has benefited some plants. Why would plants that have adaptations for only certain pollinators have an advantage? In many cases, pollinators that are restricted to certain species are more likely to transport pollen between members of that species, instead of wasting pollen by taking it to different species. 3. The United States Department of Agriculture sponsors the National Invasive Species Information Center, which has a web site at ( 4. Consider a class assignment to explore the collapse of the northern cod fishery and to identify other fish species in danger of over harvesting. Shark populations may be experiencing such a decline. As emphasized in the text, harvesting a population down to intermediate levels maximizes the sustained yield.

A reddish sea of cheatgrass threatens to overwhelm native sagebrush (green)
Figure A reddish sea of cheatgrass threatens to overwhelm native sagebrush (green) Figure 19.14

Are another invasive species Were first released into New York in 1890
European starlings Are another invasive species Were first released into New York in 1890 Now number more than 200 million in the United States Student Misconceptions and Concerns 1. Most students do not understand the dangers of relocating wildlife or letting their pet loose in a park or non-native environment. As noted in the text, the consequences of accidental or deliberate introductions costs the United States more than $130 billion a year. What might seem like a kind gesture to your students is a very dangerous activity, little understood by the public. 2. The history of the widespread abuse of pesticides in North America occurred before most of your students were born. Yet, the lessons of this recent history remind us of the potential consequences. Rachel Carson’s book Silent Spring, or passages from it, might be a good assignment for your class. Teaching Tips 1. Students are likely to expect that spraying insecticides or using various killing devices (such as bug zappers) will make a significant impact in a pest population. However, many pesticides kill pests and their predators. Further, most pest populations are capable of recovering quickly, perhaps faster than their predators. The complexity of life histories and population dynamics help to illustrate the complexities inherent to biological systems and the unexpected consequences. 2. Coevolution is illustrated by organisms that exhibit reciprocal evolutionary adaptations. Challenge students to explain how rewarding a pollinator with nectar has benefited some plants. Why would plants that have adaptations for only certain pollinators have an advantage? In many cases, pollinators that are restricted to certain species are more likely to transport pollen between members of that species, instead of wasting pollen by taking it to different species. 3. The United States Department of Agriculture sponsors the National Invasive Species Information Center, which has a web site at ( 4. Consider a class assignment to explore the collapse of the northern cod fishery and to identify other fish species in danger of over harvesting. Shark populations may be experiencing such a decline. As emphasized in the text, harvesting a population down to intermediate levels maximizes the sustained yield.

Figure 19.15 A large flock of starlings (inset) settling into a tree to roost for the night

Biological Control of Pests
Invasive species may benefit from the absence of Pathogens Predators Herbivores Student Misconceptions and Concerns 1. Most students do not understand the dangers of relocating wildlife or letting their pet loose in a park or non-native environment. As noted in the text, the consequences of accidental or deliberate introductions costs the United States more than $130 billion a year. What might seem like a kind gesture to your students is a very dangerous activity, little understood by the public. 2. The history of the widespread abuse of pesticides in North America occurred before most of your students were born. Yet, the lessons of this recent history remind us of the potential consequences. Rachel Carson’s book Silent Spring, or passages from it, might be a good assignment for your class. Teaching Tips 1. Students are likely to expect that spraying insecticides or using various killing devices (such as bug zappers) will make a significant impact in a pest population. However, many pesticides kill pests and their predators. Further, most pest populations are capable of recovering quickly, perhaps faster than their predators. The complexity of life histories and population dynamics help to illustrate the complexities inherent to biological systems and the unexpected consequences. 2. Coevolution is illustrated by organisms that exhibit reciprocal evolutionary adaptations. Challenge students to explain how rewarding a pollinator with nectar has benefited some plants. Why would plants that have adaptations for only certain pollinators have an advantage? In many cases, pollinators that are restricted to certain species are more likely to transport pollen between members of that species, instead of wasting pollen by taking it to different species. 3. The United States Department of Agriculture sponsors the National Invasive Species Information Center, which has a web site at ( 4. Consider a class assignment to explore the collapse of the northern cod fishery and to identify other fish species in danger of over harvesting. Shark populations may be experiencing such a decline. As emphasized in the text, harvesting a population down to intermediate levels maximizes the sustained yield.

Biological Control of Pests
intentional release of a natural enemy to attack a pest population used to manage an invasive species Student Misconceptions and Concerns 1. Most students do not understand the dangers of relocating wildlife or letting their pet loose in a park or non-native environment. As noted in the text, the consequences of accidental or deliberate introductions costs the United States more than $130 billion a year. What might seem like a kind gesture to your students is a very dangerous activity, little understood by the public. 2. The history of the widespread abuse of pesticides in North America occurred before most of your students were born. Yet, the lessons of this recent history remind us of the potential consequences. Rachel Carson’s book Silent Spring, or passages from it, might be a good assignment for your class. Teaching Tips 1. Students are likely to expect that spraying insecticides or using various killing devices (such as bug zappers) will make a significant impact in a pest population. However, many pesticides kill pests and their predators. Further, most pest populations are capable of recovering quickly, perhaps faster than their predators. The complexity of life histories and population dynamics help to illustrate the complexities inherent to biological systems and the unexpected consequences. 2. Coevolution is illustrated by organisms that exhibit reciprocal evolutionary adaptations. Challenge students to explain how rewarding a pollinator with nectar has benefited some plants. Why would plants that have adaptations for only certain pollinators have an advantage? In many cases, pollinators that are restricted to certain species are more likely to transport pollen between members of that species, instead of wasting pollen by taking it to different species. 3. The United States Department of Agriculture sponsors the National Invasive Species Information Center, which has a web site at ( 4. Consider a class assignment to explore the collapse of the northern cod fishery and to identify other fish species in danger of over harvesting. Shark populations may be experiencing such a decline. As emphasized in the text, harvesting a population down to intermediate levels maximizes the sustained yield.

In 1950, the Australian government introduced a virus lethal to European rabbits into the rabbits’ Australian environment. Student Misconceptions and Concerns 1. Most students do not understand the dangers of relocating wildlife or letting their pet loose in a park or non-native environment. As noted in the text, the consequences of accidental or deliberate introductions costs the United States more than $130 billion a year. What might seem like a kind gesture to your students is a very dangerous activity, little understood by the public. 2. The history of the widespread abuse of pesticides in North America occurred before most of your students were born. Yet, the lessons of this recent history remind us of the potential consequences. Rachel Carson’s book Silent Spring, or passages from it, might be a good assignment for your class. Teaching Tips 1. Students are likely to expect that spraying insecticides or using various killing devices (such as bug zappers) will make a significant impact in a pest population. However, many pesticides kill pests and their predators. Further, most pest populations are capable of recovering quickly, perhaps faster than their predators. The complexity of life histories and population dynamics help to illustrate the complexities inherent to biological systems and the unexpected consequences. 2. Coevolution is illustrated by organisms that exhibit reciprocal evolutionary adaptations. Challenge students to explain how rewarding a pollinator with nectar has benefited some plants. Why would plants that have adaptations for only certain pollinators have an advantage? In many cases, pollinators that are restricted to certain species are more likely to transport pollen between members of that species, instead of wasting pollen by taking it to different species. 3. The United States Department of Agriculture sponsors the National Invasive Species Information Center, which has a web site at ( 4. Consider a class assignment to explore the collapse of the northern cod fishery and to identify other fish species in danger of over harvesting. Shark populations may be experiencing such a decline. As emphasized in the text, harvesting a population down to intermediate levels maximizes the sustained yield.

The Process of Science: Can Biological Control Defeat Kudzu?
Is an invasive Asian vine Covers about 12,000 square miles of the southeastern United States Has a range limited by cold winters Student Misconceptions and Concerns 1. Most students do not understand the dangers of relocating wildlife or letting their pet loose in a park or non-native environment. As noted in the text, the consequences of accidental or deliberate introductions costs the United States more than $130 billion a year. What might seem like a kind gesture to your students is a very dangerous activity, little understood by the public. 2. The history of the widespread abuse of pesticides in North America occurred before most of your students were born. Yet, the lessons of this recent history remind us of the potential consequences. Rachel Carson’s book Silent Spring, or passages from it, might be a good assignment for your class. Teaching Tips 1. Students are likely to expect that spraying insecticides or using various killing devices (such as bug zappers) will make a significant impact in a pest population. However, many pesticides kill pests and their predators. Further, most pest populations are capable of recovering quickly, perhaps faster than their predators. The complexity of life histories and population dynamics help to illustrate the complexities inherent to biological systems and the unexpected consequences. 2. Coevolution is illustrated by organisms that exhibit reciprocal evolutionary adaptations. Challenge students to explain how rewarding a pollinator with nectar has benefited some plants. Why would plants that have adaptations for only certain pollinators have an advantage? In many cases, pollinators that are restricted to certain species are more likely to transport pollen between members of that species, instead of wasting pollen by taking it to different species. 3. The United States Department of Agriculture sponsors the National Invasive Species Information Center, which has a web site at ( 4. Consider a class assignment to explore the collapse of the northern cod fishery and to identify other fish species in danger of over harvesting. Shark populations may be experiencing such a decline. As emphasized in the text, harvesting a population down to intermediate levels maximizes the sustained yield. © 2010 Pearson Education, Inc.

Figure 19.16 Kudzu (Pueraria lobata)

Many strategies to control kudzu have been considered with little success.
A fungal pathogen called Myrothecium verrucaria appears to be a promising candidate for biological control. Student Misconceptions and Concerns 1. Most students do not understand the dangers of relocating wildlife or letting their pet loose in a park or non-native environment. As noted in the text, the consequences of accidental or deliberate introductions costs the United States more than $130 billion a year. What might seem like a kind gesture to your students is a very dangerous activity, little understood by the public. 2. The history of the widespread abuse of pesticides in North America occurred before most of your students were born. Yet, the lessons of this recent history remind us of the potential consequences. Rachel Carson’s book Silent Spring, or passages from it, might be a good assignment for your class. Teaching Tips 1. Students are likely to expect that spraying insecticides or using various killing devices (such as bug zappers) will make a significant impact in a pest population. However, many pesticides kill pests and their predators. Further, most pest populations are capable of recovering quickly, perhaps faster than their predators. The complexity of life histories and population dynamics help to illustrate the complexities inherent to biological systems and the unexpected consequences. 2. Coevolution is illustrated by organisms that exhibit reciprocal evolutionary adaptations. Challenge students to explain how rewarding a pollinator with nectar has benefited some plants. Why would plants that have adaptations for only certain pollinators have an advantage? In many cases, pollinators that are restricted to certain species are more likely to transport pollen between members of that species, instead of wasting pollen by taking it to different species. 3. The United States Department of Agriculture sponsors the National Invasive Species Information Center, which has a web site at ( 4. Consider a class assignment to explore the collapse of the northern cod fishery and to identify other fish species in danger of over harvesting. Shark populations may be experiencing such a decline. As emphasized in the text, harvesting a population down to intermediate levels maximizes the sustained yield.

Integrated Pest Management
Agricultural operations create their own highly managed ecosystems that Have genetically similar individuals (a monoculture) Are planted in close proximity to each other Function as a “banquet” for Plant-eating animals Pathogenic bacteria Viruses Student Misconceptions and Concerns 1. Most students do not understand the dangers of relocating wildlife or letting their pet loose in a park or non-native environment. As noted in the text, the consequences of accidental or deliberate introductions costs the United States more than $130 billion a year. What might seem like a kind gesture to your students is a very dangerous activity, little understood by the public. 2. The history of the widespread abuse of pesticides in North America occurred before most of your students were born. Yet, the lessons of this recent history remind us of the potential consequences. Rachel Carson’s book Silent Spring, or passages from it, might be a good assignment for your class. Teaching Tips 1. Students are likely to expect that spraying insecticides or using various killing devices (such as bug zappers) will make a significant impact in a pest population. However, many pesticides kill pests and their predators. Further, most pest populations are capable of recovering quickly, perhaps faster than their predators. The complexity of life histories and population dynamics help to illustrate the complexities inherent to biological systems and the unexpected consequences. 2. Coevolution is illustrated by organisms that exhibit reciprocal evolutionary adaptations. Challenge students to explain how rewarding a pollinator with nectar has benefited some plants. Why would plants that have adaptations for only certain pollinators have an advantage? In many cases, pollinators that are restricted to certain species are more likely to transport pollen between members of that species, instead of wasting pollen by taking it to different species. 3. The United States Department of Agriculture sponsors the National Invasive Species Information Center, which has a web site at ( 4. Consider a class assignment to explore the collapse of the northern cod fishery and to identify other fish species in danger of over harvesting. Shark populations may be experiencing such a decline. As emphasized in the text, harvesting a population down to intermediate levels maximizes the sustained yield.

Like invasive species, most crop pests
Have an opportunistic life history pattern Can cause extensive crop damage Student Misconceptions and Concerns 1. Most students do not understand the dangers of relocating wildlife or letting their pet loose in a park or non-native environment. As noted in the text, the consequences of accidental or deliberate introductions costs the United States more than $130 billion a year. What might seem like a kind gesture to your students is a very dangerous activity, little understood by the public. 2. The history of the widespread abuse of pesticides in North America occurred before most of your students were born. Yet, the lessons of this recent history remind us of the potential consequences. Rachel Carson’s book Silent Spring, or passages from it, might be a good assignment for your class. Teaching Tips 1. Students are likely to expect that spraying insecticides or using various killing devices (such as bug zappers) will make a significant impact in a pest population. However, many pesticides kill pests and their predators. Further, most pest populations are capable of recovering quickly, perhaps faster than their predators. The complexity of life histories and population dynamics help to illustrate the complexities inherent to biological systems and the unexpected consequences. 2. Coevolution is illustrated by organisms that exhibit reciprocal evolutionary adaptations. Challenge students to explain how rewarding a pollinator with nectar has benefited some plants. Why would plants that have adaptations for only certain pollinators have an advantage? In many cases, pollinators that are restricted to certain species are more likely to transport pollen between members of that species, instead of wasting pollen by taking it to different species. 3. The United States Department of Agriculture sponsors the National Invasive Species Information Center, which has a web site at ( 4. Consider a class assignment to explore the collapse of the northern cod fishery and to identify other fish species in danger of over harvesting. Shark populations may be experiencing such a decline. As emphasized in the text, harvesting a population down to intermediate levels maximizes the sustained yield.

Figure 19.18 Plants infested with Japanese beetles (left) and grasshoppers (right)

36.9 The human population continues to increase, but the growth rate is slowing
Human population is expected to continue increasing for several decades 95% of the increase is in developing nations Student Misconceptions and Concerns 1. Some students may not understand the impact of delayed reproduction on population growth. Working through the following example in class might help. Refer back to the text example of exponential growth in a population of bacteria (Module 36.4). What if one population reproduced every 20 minutes and another population reproduced every 40 minutes? Clearly, the 20-minute cycle would increase the population faster. Teaching Tips 1. You might surprise your class by noting that the majority of the people who have ever lived in the history of the human race are alive today. An examination of Figure 36.9A reveals how this could be true. 2. The U.S. government’s Census Bureau sponsors a U.S. and world population clock at Copyright © 2009 Pearson Education, Inc.

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

Table 36.9 Population Changes in 2006.

per 1,000 population Birth or death rate
50 40 30 per 1,000 population Birth or death rate Rate of increase (r) 20 Birth rate Death rate 10 Figure 36.9B Demographic transition in Mexico. 1900 1925 1950 1975 2000 2025 2050 Year

36.11 CONNECTION: An ecological footprint is a measure of resource consumption
U.S. Census Bureau projection 8 billion people within the next 20 years 9.5 billion by mid-21st century Student Misconceptions and Concerns 1. Some students may not understand the impact of delayed reproduction on population growth. Working through the following example in class might help. Refer back to the text example of exponential growth in a population of bacteria (Module 36.4). What if one population reproduced every 20 minutes and another population reproduced every 40 minutes? Clearly, the 20-minute cycle would increase the population faster. 2. Students are often frustrated by the long list of environmental problems caused by humans, and many begin to feel helpless as coverage of the issues goes on. You might consider directing them to the following websites for basic suggestions on what they can do to start to make a difference. Teaching Tips 1. Module notes that the United States has an ecological footprint greater than the land area of the United States. Consider asking your class to explain how this is possible and what this means to other countries. The authors further note that only 14% of the global resources are available for 80% of the world’s population. Copyright © 2009 Pearson Education, Inc.

36.11 CONNECTION: An ecological footprint is a measure of resource consumption
Ecological footprint helps understand resource availability and usage The United States has a Big ecological footprint Large ecological deficit Student Misconceptions and Concerns 1. Some students may not understand the impact of delayed reproduction on population growth. Working through the following example in class might help. Refer back to the text example of exponential growth in a population of bacteria (Module 36.4). What if one population reproduced every 20 minutes and another population reproduced every 40 minutes? Clearly, the 20-minute cycle would increase the population faster. 2. Students are often frustrated by the long list of environmental problems caused by humans, and many begin to feel helpless as coverage of the issues goes on. You might consider directing them to the following websites for basic suggestions on what they can do to start to make a difference. Teaching Tips 1. Module notes that the United States has an ecological footprint greater than the land area of the United States. Consider asking your class to explain how this is possible and what this means to other countries. The authors further note that only 14% of the global resources are available for 80% of the world’s population. Copyright © 2009 Pearson Education, Inc.

Figure 36.11A Families in India (left) and the United States (right) display their possessions.

Concept Check Predict which survivorship curve would best describe most whale species. Type I Type II Type III Answer: 1

Answer Predict which survivorship curve would best describe most whale species Type I

Concept Check Predict which survivorship curve would best describe a fish like a carp (Cyprinus carpio). A large female carp can produce more than a million eggs. Type I Type II Type III Answer: 3

Answer Predict which survivorship curve would best describe a fish like a carp (Cyprinus carpio). A large female carp can produce more than a million eggs. Type III

Concept Check Predict which survivorship curve would best describe most whale species. Type I Type II Type III Answer: 1

Answer Predict which survivorship curve would best describe most whale species Type I

Concept Check Predict which survivorship curve would best describe a fish like a carp (Cyprinus carpio). A large female carp can produce more than a million eggs. Type I Type II Type III Answer: 3

Answer Predict which survivorship curve would best describe a fish like a carp (Cyprinus carpio). A large female carp can produce more than a million eggs. Type III

Concept Check The ecological footprint is one way to calculate the Earth’s carrying capacity for human populations. At current consumption rates, a child born today in an industrialized country will add more to consumption and pollution during her/his lifetime than 5-10 children born in developing countries. 10-15 children born in developing countries. 20 children born in developing countries. 30-50 children born in developing countries. Answer: 4

Answer The ecological footprint is one way to calculate the Earth’s carrying capacity for human populations. At current consumption rates, a child born today in an industrialized country will add more to consumption and pollution during her/his lifetime than 30-50 children born in developing countries.

Thinking Like a Scientist
Thinking Like a Scientist This figure plots the breeding populations of fur seals as they recovered from uncontrolled hunting. Based on this graph what is the approximate carrying capacity of the fur seal’s breeding habitat? About 1000 seals. About 5000 seals About 10,000 seals Answer: 3

Answer This figure plots the breeding populations of fur seals as they recovered from uncontrolled hunting. Based on this graph what is the approximate carrying capacity of the fur seal’s breeding habitat? About 10,000 seals

Thinking Like a Scientist The maximum rate of increase for the seal population on the island occurred during which decade? Answer: 2

Answer The maximum rate of increase for the seal population on the island occurred during which decade?

Thinking Like a Scientist This graph plots the difference between birth rates and death rates for Mexico during the 20th century. During which quarter century did Mexico experience the greatest rate of population growth? Answer: 3

Answer This graph plots the difference between birth rates and death rates for Mexico during the 20th century. During which quarter century did Mexico experience the greatest rate of population growth?

Strongly A B C D E Strongly
Science and Society Most scientists agree that the most pressing environmental issue facing human society is population growth. Scientist disagree on whether the rising rate of consumption in the developed countries is a greater problem than the rapid population growth in undeveloped countries. How do you rate this problem? Disagree Agree Strongly A B C D E Strongly

Science and Society Renewable resource management is challenging. Populations of whitetail deer today live in areas with few natural predators. Their populations have expanded exponentially. Population control methods include hunting—even in urban areas. Do you think that controlled hunting should be used to manage deer populations in urban areas? Disagree Agree Strongly A B C D E Strongly

Science and Society Populous nations such as China have instituted strict policies to curb population growth. In 1979, China implemented a “one-child” policy. Do you think that such strict control methods are appropriate for population control? Disagree Agree Strongly A B C D E Strongly

Chapter 36 Population Ecology.

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Chapter 36 Population Ecology.

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