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Chapter 19 Table of Contents Section 1 Understanding Populations Section 2 Measuring Populations Section 3 Human Population Growth

Section 1 Understanding Populations Chapter 19 Objectives Describe the main properties that scientists measure when they study populations. Compare the three general patterns of population dispersion. Identify the measurements used to describe changing populations. Compare the three general types of survivorship curves.

Properties of Populations Section 1 Understanding Populations Chapter 19 Properties of Populations A population is a group of organisms that belong to the same species and live in a particular place at the same time. Populations can be measured in terms of size, density, dispersion, growth rate, age structure, and survivorship.

Section 1 Understanding Populations Chapter 19 Population

Properties of Populations, continued Section 1 Understanding Populations Chapter 19 Properties of Populations, continued Population Size A population’s size is the number of individuals that the population contains.

Properties of Populations, continued Section 1 Understanding Populations Chapter 19 Properties of Populations, continued Population Density Density is a measure of how crowded the population is.

Properties of Populations, continued Section 1 Understanding Populations Chapter 19 Properties of Populations, continued Dispersion Dispersion describes the distribution of individuals within the population and may be random, uniform, or clumped.

Three Patterns of Population Dispersion Section 1 Understanding Populations Chapter 19 Three Patterns of Population Dispersion

Characteristics of Populations Section 1 Understanding Populations Chapter 19 Characteristics of Populations

Chapter 19 Population Dynamics Age Structure Section 1 Understanding Populations Chapter 19 Population Dynamics Age Structure A population’s age structure indicates the percentage of individuals at each age.

Population Dynamics, continued Section 1 Understanding Populations Chapter 19 Population Dynamics, continued Patterns of Mortality Populations show three patterns of mortality or survivorship curves: Type I (low mortality until late in life) Type II (constant mortality throughout life) Type III (high mortality early in life followed by low mortality for the remaining life span).

Section 1 Understanding Populations Chapter 19 Survivorship Curves

Section 2 Measuring Populations Chapter 19 Objectives Identify the four processes that determine population growth. Compare the exponential model and the logistic model of population growth. Differentiate between density-dependent and density-independent regulation of populations. Explain why small populations are more vulnerable to extinction.

Population Growth Rate Section 2 Measuring Populations Chapter 19 Population Growth Rate Demographers, scientists who study population dynamics, define the growth rate of a population as the amount by which a population’s size changes in a given time.

Population Growth Rate, continued Section 2 Measuring Populations Chapter 19 Population Growth Rate, continued Population Size Birth rate - death rate = growth rate

Chapter 19 The Exponential Model Section 2 Measuring Populations Chapter 19 The Exponential Model The exponential model describes perpetual growth at a steady rate in a population. The model assumes constant birth and death rates and no immigration or emigration.

Section 2 Measuring Populations Chapter 19 Exponential Growth

Chapter 19 The Logistic Model Section 2 Measuring Populations Chapter 19 The Logistic Model In the logistic model, birth rates fall and death rates climb as the population grows. When the carrying capacity is reached, the number of individuals the environment can support is reached and population growth becomes stable.

Section 2 Measuring Populations Chapter 19 Logistic Model

Two Population Growth Models Section 2 Measuring Populations Chapter 19 Two Population Growth Models

Population Regulation Section 2 Measuring Populations Chapter 19 Population Regulation Population-limiting factors, such as competition, are density-dependent because the effect on each individual depends on the number of other individuals present in the same area.

Population Regulation, continued Section 2 Measuring Populations Chapter 19 Population Regulation, continued Population-limiting factors, such as bad weather and fires, are density-independent because the effect on each individual does not depend on the number of other individuals present in the same area.

Comparing Density-Dependent and Density-Independent Factors Section 2 Measuring Populations Chapter 19 Comparing Density-Dependent and Density-Independent Factors

Population Regulation, continued Section 2 Measuring Populations Chapter 19 Population Regulation, continued Population Fluctuations All populations fluctuate in size.

Population Regulation, continued Section 2 Measuring Populations Chapter 19 Population Regulation, continued Perils of Small Populations Small populations have low genetic diversity and are subject to inbreeding, so they are less likely to adapt to environmental changes.

Section 3 Human Population Growth Chapter 19 Objectives Explain how the development of agriculture changed the pattern of human population growth. Describe changes in human population size in the past 10,000 years. Compare observed patterns of population growth in developed and developing countries.

History of Human Population Growth Section 3 Human Population Growth Chapter 19 History of Human Population Growth The Development of Agriculture About 10,000 to 12,000 years ago, the development of agriculture increased the growth rate of the human population.

History of Human Population Growth, continued Section 3 Human Population Growth Chapter 19 History of Human Population Growth, continued The Population Explosion Around 1650, improvements in hygiene, diet, and economic conditions further accelerated population growth. After World War II, the human population grew at the fastest rate in history, largely because of better sanitation and medical care in poorer countries.

History of Human Population Growth, continued Section 3 Human Population Growth Chapter 19 History of Human Population Growth, continued Population Growth Today Today, developing countries have faster human population growth and lower standards of living than developed countries do.

Human Population Growth Section 3 Human Population Growth Chapter 19 Human Population Growth

Demographic Transition Section 3 Human Population Growth Chapter 19 Demographic Transition Human populations have undergone rapid growth, yet in some developed countries, populations have stopped growing. The demographic transition model shows how these population changes happen.

Demographic Transition Model Section 3 Human Population Growth Chapter 19 Demographic Transition Model

Chapter 19 Multiple Choice 1. Which of the following is a population? Standardized Test Prep Multiple Choice 1. Which of the following is a population? A. all the fish in a pond B. all the birds in New York City C. all the members of a family of humans D. all the fish of the same species in a lake

Multiple Choice, continued Chapter 19 Standardized Test Prep Multiple Choice, continued 1. Which of the following is a population? A. all the fish in a pond B. all the birds in New York City C. all the members of a family of humans D. all the fish of the same species in a lake

Multiple Choice, continued Chapter 19 Standardized Test Prep Multiple Choice, continued 2. Which of the following is true in the exponential model of population growth? F. Population growth continues indefinitely. G. Population growth stops at the carrying capacity. H. Population growth increases and then decreases. J. The immigration rate falls with increasing population size.

Multiple Choice, continued Chapter 19 Standardized Test Prep Multiple Choice, continued 2. Which of the following is true in the exponential model of population growth? F. Population growth continues indefinitely. G. Population growth stops at the carrying capacity. H. Population growth increases and then decreases. J. The immigration rate falls with increasing population size.

Multiple Choice, continued Chapter 19 Standardized Test Prep Multiple Choice, continued 3. Which of the following refers to the population size that can be sustained by an environment over time? A. bell curve B. allele frequency C. carrying capacity D. exponential growth

Multiple Choice, continued Chapter 19 Standardized Test Prep Multiple Choice, continued 3. Which of the following refers to the population size that can be sustained by an environment over time? A. bell curve B. allele frequency C. carrying capacity D. exponential growth

Multiple Choice, continued Chapter 19 Standardized Test Prep Multiple Choice, continued 4. Which of the following is a density-dependent factor for a population of deer in a forest? F. a drought G. a landslide H. a period of freezing weather J. the number of cougars in the forest

Multiple Choice, continued Chapter 19 Standardized Test Prep Multiple Choice, continued 4. Which of the following is a density-dependent factor for a population of deer in a forest? F. a drought G. a landslide H. a period of freezing weather J. the number of cougars in the forest

Multiple Choice, continued Chapter 19 Standardized Test Prep Multiple Choice, continued Use the graph below to answer question 5. The graph shows the size of a particular population over time. 5. In the graph, which time period shows negative growth of the population? A. phase 1 B. phase 2 C. phase 3 D. phase 4

Multiple Choice, continued Chapter 19 Standardized Test Prep Multiple Choice, continued Use the graph below to answer question 5. The graph shows the size of a particular population over time. 5. In the graph, which time period shows negative growth of the population? A. phase 1 B. phase 2 C. phase 3 D. phase 4

Multiple Choice, continued Chapter 24 Standardized Test Prep Multiple Choice, continued Complete the following analogy: 6. birth rate : death rate :: immigration : F. mortality G. migration H. emigration J. growth rate

Multiple Choice, continued Chapter 24 Standardized Test Prep Multiple Choice, continued Complete the following analogy: 6. birth rate : death rate :: immigration : F. mortality G. migration H. emigration J. growth rate

Multiple Choice, continued Chapter 19 Standardized Test Prep Multiple Choice, continued Use the graph below to answer question 7. The graph shows the growth of a population of fruit flies over time. 7. At which point would a density-dependent limiting factor have a greater impact on the population? A. 1 B. 2 C. 3 D. Both 1 and 3

Multiple Choice, continued Chapter 19 Standardized Test Prep Multiple Choice, continued Use the graph below to answer question 7. The graph shows the growth of a population of fruit flies over time. 7. At which point would a density-dependent limiting factor have a greater impact on the population? A. 1 B. 2 C. 3 D. Both 1 and 3

Chapter 19 Short Response Standardized Test Prep Short Response Study the graph of fruit fly population growth on the previous slide. Explain why the population stops increasing after it reaches the point labeled 3 on the curve.

Short Response, continued Chapter 19 Standardized Test Prep Short Response, continued Study the graph of fruit fly population growth on the previous slide. Explain why the population stops increasing after it reaches the point labeled 3 on the curve. Answer: At point 3, the population has stopped exponential growth and has reached its carrying capacity. Limiting factors usually slow population growth down.

Chapter 19 Extended Response Standardized Test Prep Base your answers to parts A & B on the information below. Study the graph of fruit fly population growth again. Use the graph to support your answers to the following questions. Part A Name one limiting factor that could affect this population of fruit flies. Part B At which point on the curve would this limiting factor have the greatest effect on the population? Explain your reasoning.

Extended Response, continued Chapter 19 Standardized Test Prep Extended Response, continued Answer: Part A Food availability is one limiting factor that could affect population growth. Part B Food availability will affect the population at every point along the growth curve. Without food, the population could not experience unlimited growth as shown in area 2. However, food availability has its greatest effect at the carrying capacity, or area 3 on the curve. At the carrying capacity, the environment is supporting the maximum number of individuals based on available resources. Less food will lead to a sudden decrease in population.