Population Structure and Dynamics Figure 36.0-2 Chapter 36: Big Ideas 1989 Male Female Figure 36.0-2 Chapter 36: Big Ideas Population Structure and Dynamics The Human Population

THE HUMAN POPULATION 1. Explain how the structure of the world’s human population has changed and continues to change. 2. Explain how the age structure of a population can be used to predict changes in population size and social conditions. 3. Explain the concept of an ecological footprint.

36.9 The human population continues to increase, but the growth rate is slowing grew rapidly during the 20th century and currently stands at about 7 billion. An imbalance between births and deaths is the cause of population growth (or decline). The human population is expected to continue increasing for at least the next several decades. Student Misconceptions and Concerns  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  The U.S. government’s Census Bureau sponsors a U.S. and World Population Clock at http://www.census.gov/popclock/. There are many interesting aspects of human populations at this site. If your facilities and technology permit, this would be a great screen to have up before class starts!

Total population (in billions) Annual increase (in millions) Figure 36.9a 100 10 Population increase 80 8 Total population (in billions) Annual increase (in millions) 60 6 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 Adapted from The World at Six Billion, United Nations Publications (1999).

36.9 The human population continues to increase, but the growth rate is slowing The demographic transition is a shift from zero population growth, in which birth rates and death rates are high but roughly equal, to zero population growth, due to low but roughly equal birth and death rates. Ex: Mexico Student Misconceptions and Concerns  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  The U.S. government’s Census Bureau sponsors a U.S. and World Population Clock at http://www.census.gov/popclock/. There are many interesting aspects of human populations at this site. If your facilities and technology permit, this would be a great screen to have up before class starts!

36.9 The human population continues to increase, but the growth rate is slowing In the developing world death rates have dropped, but high birth rates persist, and these populations are growing rapidly. Student Misconceptions and Concerns  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  The U.S. government’s Census Bureau sponsors a U.S. and World Population Clock at http://www.census.gov/popclock/. There are many interesting aspects of human populations at this site. If your facilities and technology permit, this would be a great screen to have up before class starts!

36.9 The human population continues to increase, but the growth rate is slowing The age structure of a population is the number of individuals in different age-groups affects the future growth of the population. Student Misconceptions and Concerns  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  The U.S. government’s Census Bureau sponsors a U.S. and World Population Clock at http://www.census.gov/popclock/. There are many interesting aspects of human populations at this site. If your facilities and technology permit, this would be a great screen to have up before class starts!

36.9 The human population continues to increase, but the growth rate is slowing The fertility rate is the average number of children produced by a woman over her lifetime. Population momentum is the continued growth that occurs despite reduction of the fertility rate to replacement level result of girls in the 0–14 age-group of a previously expanding population reaching their childbearing years. Student Misconceptions and Concerns  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  The U.S. government’s Census Bureau sponsors a U.S. and World Population Clock at http://www.census.gov/popclock/. There are many interesting aspects of human populations at this site. If your facilities and technology permit, this would be a great screen to have up before class starts!

36.10 CONNECTION: Age structures reveal social and economic trends Age-structure diagrams reveal a population’s future growth trends and social conditions. For instance, an expanding population has an increasing need for schools, employment, and infrastructure, and a large elderly population requires that extensive resources be allotted to health care. Student Misconceptions and Concerns  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  Module 36.10 provides a wonderful opportunity to discuss the social impact of human population changes in the United States. As noted in Module 36.10, Medicare and Social Security will be increasingly impacted as the U.S. population ages. You might want to discuss the occupational outlook for professions that will address the needs of the growing elderly population, and the opportunity to invest in companies that will capitalize on these changes.

36.11 CONNECTION: An ecological footprint is a measure of resource consumption The U.S. Census Bureau projects a global population of 8 billion people within the next 20 years and 9.5 billion by the mid-21st century. Do we have sufficient resources to sustain 8 or 9 billion people? To accommodate all the people expected to live on our planet by 2025, the world will have to double food production. Student Misconceptions and Concerns  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.  Students are often frustrated by the long list of environmental problems caused by humans, and students may begin to feel helpless as coverage of the issues goes on. You might consider directing them to specific websites for basic suggestions on what they can do to make a difference. A Google search of “what you can do environment” should yield many potentially good sites. Teaching Tips  Module 36.11 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 the world’s richest countries, with 15% of the global population, account for 36% of humanity’s total footprint. Active Lecture Tips  See the Activity The Carbon Footprint on the Instructor Exchange. Visit the Instructor Exchange in the MasteringBiology instructor resource area for a description of this activity.

History of Human Population Growth http://www.npr.org/2011/10/31/141816460/visualizin g-how-a-population-grows-to-7-billion?ps=cprs

36.11 CONNECTION: An ecological footprint is a measure of resource consumption An ecological footprint is an estimate of the amount of land required to provide the raw materials an individual or a nation consumes, including food, fuel, and housing. Student Misconceptions and Concerns  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.  Students are often frustrated by the long list of environmental problems caused by humans, and students may begin to feel helpless as coverage of the issues goes on. You might consider directing them to specific websites for basic suggestions on what they can do to make a difference. A Google search of “what you can do environment” should yield many potentially good sites. Teaching Tips  Module 36.11 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 the world’s richest countries, with 15% of the global population, account for 36% of humanity’s total footprint. Active Lecture Tips  See the Activity The Carbon Footprint on the Instructor Exchange. Visit the Instructor Exchange in the MasteringBiology instructor resource area for a description of this activity.

36.11 CONNECTION: An ecological footprint is a measure of resource consumption Comparing our demand for resources with Earth’s capacity to renew these resources, or biocapacity, gives us a broad view of the sustainability of human activities. Student Misconceptions and Concerns  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.  Students are often frustrated by the long list of environmental problems caused by humans, and students may begin to feel helpless as coverage of the issues goes on. You might consider directing them to specific websites for basic suggestions on what they can do to make a difference. A Google search of “what you can do environment” should yield many potentially good sites. Teaching Tips  Module 36.11 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 the world’s richest countries, with 15% of the global population, account for 36% of humanity’s total footprint. Active Lecture Tips  See the Activity The Carbon Footprint on the Instructor Exchange. Visit the Instructor Exchange in the MasteringBiology instructor resource area for a description of this activity.

Earth’s Overshoot http://www.footprintnetwork.org/en/index.php/GFN/ page/video_overshoot_explained/

You should now be able to Define a population and population ecology. Define population density and describe different types of dispersion patterns. Explain how life tables are used to track mortality and survivorship in populations. Compare Type I, Type II, and Type III survivorship curves. Describe and compare the exponential and logistic population growth models, illustrating both with examples.

You should now be able to Explain the concept of carrying capacity. Describe the factors that regulate growth in natural populations. Define boom-and-bust cycles, explain why they occur, and provide examples. Explain how life history traits vary with environmental conditions and with population density. Compare r-selection and K-selection and indicate examples of each.

You should now be able to Describe the major challenges inherent in managing populations. Explain how the structure of the world’s human population has changed and continues to change. Explain how the age structure of a population can be used to predict changes in population size and social conditions. Explain the concept of an ecological footprint. Describe the uneven reliance upon natural resources in the world.

Few large offspring, low mortality until old age Figure 36.UN01 Few large offspring, low mortality until old age I Percentage of survivors Many small offspring, high mortality II III Figure 36.UN01 Reviewing the concepts, 36.3 Percentage of maximum life span

Population in millions Estimated population in millions Figure 36.UN02 80+ 1989 2012 75–79 70–74 Male Female Male Female 65–69 60–64 55–59 50–54 Age 45–49 40–44 35–39 30–34 25–29 20–24 15–19 10–14 Figure 36.UN02 Reviewing the concepts, 36.10 5–9 0–4 6 5 4 3 2 1 0 1 2 3 4 5 6 5 4 3 2 1 0 1 2 3 4 5 Population in millions Estimated population in millions Total population size = 83,366,836 Total population size = 114,975,406

Figure 36.UN03 (K − N) G = rN K Figure 36.UN03 Connecting the concepts, question 1

I II III IV Birth or death rate Time Figure 36.UN04 Figure 36.UN04 Connecting the concepts, question 2 Time

Figure 36.UN05 Figure 36.UN05 Testing your knowledge, question 12