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30
ECOLOGY
OF
POPULATIONS
CHAPTER REVIEW
The human population exhibits clumped distribution and
growth is so rapid that the doubling time is only about 23
years. The growth rate for the more-developed countries
(MDCs) is about 0.1% and for the less-developed countries (LDCs) is about 1.6%. The LDCs put stress on the
biosphere due to population growth and the MDCs put stress
on the biosphere due to resource consumption.
Population growth occurs when resources are available. Populations have a characteristic age structure, sur-
vivorship, and biotic potential, which are the population’s demographics. The two possible patterns of population growth are exponential accelerating growth and
logistic stabilizing growth. Both density-independent
and density-dependent factors affect population growth.
Opportunistic populations undergo exponential growth
and equilibrium populations exhibit logistic growth. Opportunistic populations are less likely to become extinct.
CHAPTER KEY TERMS
After studying the key terms of this chapter, match the phrases below with the alphabetized list of terms.
age structure
ecosystem
biotic potential
exponential growth
carrying capacity
extinction
community
life history
demographics
logistic growth
density-dependent factor
population
density-independent factor
resource
ecology
survivorship
a. study of the interactions of organisms with other organisms and the physical environment ____________________
b. shows the number of individuals in each age group in a population _______________________
c. probability of individuals of a cohort surviving to particular ages _______________________
d. adaptations that influence a population’s demographics _______________________
e. assemblage of populations interacting with one another within the same environment _______________________
f. affects population size according to the population’s density _______________________
g. affects population size independent of the population’s density_______________________
h. maximum population growth rate under ideal conditions _______________________
i. environmental supply that fulfills a need of the population _______________________
j. growth in which the increase occurs in the same manner as compound interest _______________________
k. group of organisms of the same species occupying a certain area and sharing a common gene pool
_______________________
l. population increase that results in an S-shaped curve _______________________
m. total disappearance of a species or higher classification category _______________________
n. largest population size that can be maintained indefinitely by a given environment _______________________
o. study of human populations, their characteristics, and their changes _______________________
p. consists of a community of living organisms as well as their physical environment _______________________
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S T U DY E X E R C I S E S
Study the text section by section as you answer the questions that follow.
30.1 THE HUMAN POPULATION (PP. 534–537)
• Humans have a clumped distribution pattern. Population densities are highest along the coasts of all the
continents.
• The human population is undergoing rapid growth, and most of this growth takes place in the less-developed
countries.
• Comparisons of age structures indicates future growth trends.
• Most resource consumption and pollution occur in more-developed countries.
1. Study the following diagram of human population growth and answer the question:
Population (billions)
2
Modern Science
and Medicine
1.5
1
0.5
Industrial
Revolution
Black
Plague
0
1200
1400
1600
1800
2000
What two events apparently caused the modern increase in population growth?
a.
more deaths than births
b.
LDCs increased in number and MDCs decreased in number
c.
industrial revolution and modern science
d.
All of these events were a cause.
2. A student is calculating the growth rate of today’s human population: (22–9)/1,000 = (13)/1,000 = 1.3%.
What is 22–9?
a.
number of deaths minus number of births
b.
number of births minus number of deaths
c.
number of deaths minus number of births per every 1,000 square miles
d.
number of deaths minus number of births per every 1,000 people
3. A growth rate of 1.3% seems small. Why will it result in such a large number of people next year?
a.
have to multiply 1.3% of the total number of people in the world
b.
The human population is very large.
c.
The human population has a clumped distribution.
d.
Only the LDCs participate in increased populations.
e.
Both a and b are correct.
4. Which statement is true of global growth rates? The highest growth rates are found in:
a.
Alaska and Greenland.
b.
the islands of the world.
c.
Africa and the Middle East.
d.
the United States and Canada.
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5. a. What is the approximate current doubling time for the world population: 100, 75, 50, or 25 years?
b. How many people will there be after 25 years? _____________________________________________________
6. Place the appropriate letters next to each statement:
LDC—less-developed countries
a.
b.
c.
d.
e.
f.
MDC—more-developed countries
more industrialized countries
less industrialized countries
age structure diagram resembles a pyramid
have undergone the demographic transition
are undergoing the demographic transition
Age structure diagram is stabilizing.
7. a. What is replacement reproduction? _______________________________________________________________________
b. When does replacement reproduction equate to zero population growth? __________________________________
c. Which set of countries could practice replacement reproduction and have no future growth? _______________
8. Which set of countries has the greatest environmental impact because of resource consumption? ____________
30.2 CHARACTERISTICS
•
•
•
•
OF
POPULATIONS (PP. 538–543)
Populations have a particular distribution and density.
Population growth is dependent on the birthrate versus the death rate.
Population demographics such as age and survivorship influence growth.
Population growth is exponential when biotic potential expresses itself or logistic when resources are limited.
9. Populations vary in density (number of individuals per area) and distribution of populations. Use these labels
to describe distribution:
clumped
random
uniform
a.
b.
c.
10. Calculate the growth rate, when the birthrate is .06 per capita per unit time and the death rate is .04 per capita
per unit time:
a. ______
–
b. ______
=
c. ______
per capita unit time
d. Consider a population of panthers in the Florida Everglades with this growth rate:
The unit time = 1 year and the population = 50 panthers. How many panthers would there be after a year?
______________
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11. Label the following diagram of age structures:
Age Structure
postreproductive
reproductive
prereproductive
a.
b.
c.
d. Which age structure diagram represents a decreasing population? Why? __________________________________
e. Which age structure diagram represents a growing population? Why? _____________________________________
12. Study the following diagram of survivorship curves and then answer the questions:
Number of Survivors
I
II
III
Age
a. Which curve shows that the members of a cohort die at a constant rate? ______________
b. Which curve shows that the members of a cohort tend to die early in life? ______________
c. Which curve shows that the members of a cohort usually live through their entire allotted life span?
______________
13. What is biotic potential? The highest possible rate of increase when ______________ are unlimited.
14. Choose the appropriate word to complete the description of a population with a high biotic potential:
a. started reproduction at an (early) (mature) age
b. young usually (survived until reproduction) (died before reproduction)
c. reproduced every (few months) (several years)
d. has a (large) (small) number of offspring
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Questions 15–20 pertain to the following two population growth curves:
700
600
Number of Yeast Cells
Population (thousands)
70
60
50
40
30
20
400
300
200
100
10
0
500
1
2
3
4 5 6 7
Generations
8
9
2
10
a.
4
6
8
10 12
Time (hours)
14
16
18
b.
15. Place the label ep for exponential growth pattern or lg for logistic growth pattern beneath the appropriate
figure.
16. Which of these two growth curves has a lag phase? ______________ Place this label where appropriate on the
curve(s).
17. Which of these two growth curves has an exponential growth phase? ______________ Place this label where
appropriate on the curve(s).
18. During the lag phase, growth is a. ______________; during the exponential growth phase, growth is
b. ______________.
19. Which of these two growth curves has a deceleration phase? ______________ Place this label where
appropriate on the curve(s).
20. Which of these two growth curves has a stable equilibrium phase? ______________ Place this label where
appropriate on the curve(s).
21. Which of the phases of a growth curve (lag, exponential, deceleration, or stable equilibrium) best represents
the biotic potential of a population? _________________________________________________________________
22. Why does population size level off? The
determine
b. ____________________
a. ____________________
size. This is the
of a population
c. ____________________
of the environment.
FACTORS THAT REGULATE POPULATION GROWTH
(PP. 542–543)
• Population growth is regulated by density-independent (abiotic) and density-dependent (biotic) factors.
23. Place the appropriate letters next to each statement.
DI—density-independent
a.
competition, predation (i.e., biotic factors)
b.
percentage that die remains the same despite size of population
c.
percentage that die increases with size of population
d.
natural disaster (i.e., nonbiotic factors)
DD—density-dependent
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24. The Canadian lynx preys on the snowshoe hare.
a. When the hare has a limited food source, what will happen to the size of both populations? ______________
b. What does this show? That ______________ does not necessarily cause the cycling of a lynx and snowshoe hare
population.
30.3 LIFE HISTORY PATTERNS
(PP. 544–545)
AND
EXTINCTION
• Opportunistic populations have characteristics that allow them to survive unfavorable conditions and disperse
easily.
• Equilibrium populations have characteristics that make it difficult for them to survive unfavorable conditions.
• Extinction is more likely in equilibrium populations with limited range.
25. Place the appropriate letters next to each statement:
OP—opportunistic populations
a.
b.
c.
d.
e.
f.
g.
h.
i.
EP—equilibrium populations
regulated by density-dependent effects
exponential growth
lower biotic potential
regulated by density-independent effects
most subject to possible extinction
exceeds carrying capacity and good dispersal techniques
logistic growth
higher biotic potential
stays within carrying capacity, few dispersal techniques
30.4 THE SCOPE
OF
ECOLOGY (PP. 546–547)
• Ecology is the study of the interactions of organisms with each other and with the physical environment.
• Ecologists study these levels of biological organization: organism, population, community, ecosystem, and
biosphere.
26. Match the statement to these levels of ecological study:
community
a.
b.
c.
d.
e.
f.
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ecosystem
______________________
______________________
______________________
______________________
______________________
______________________
population
biosphere
a group of populations interacting in an area
a community interacting with its physical environment
all the individuals of the same species in an area
portion of Earth’s surface where living things exist
Focus of ecological study is growth and regulation of size.
Focus of ecological study is interactions such as predation and competition
between populations.
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K E Y WO R D C RO S S WO R D
Review key terms by completing this crossword puzzle, using the following alphabetized list of terms:
1
2
3
4
5
6
7
8
age structure
biotic potential
carrying capacity
community
ecology
exponential growth
population
range
survivorship
uniform
9
10
Across
1 shows the number of individuals in each age group
in a population (two words)
7 group of organisms of the same species occupying
the same area
10 populations interacting with one another within the
same environment
Down
2 study of the interaction of organisms with other organisms and with the physical environment
3
4
5
6
8
9
percentage of a population that dies over time; usually shown graphically
maximum size of a population that can be supported
by the resources of an environment (two words)
accelerating population growth (two words)
maximum growth rate that can occur under ideal
circumstances (two words)
equal spatial distribution of individuals in a population
portion of the globe where a certain species can be
found
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CHAPTER TEST
OBJECTIVE QUESTIONS
Do not refer to the text when taking this test.
1. Select the incorrect association.
a. population—all the members of a species in
same area
b. community—populations interacting with the
physical environment
c. biosphere—surface of the earth where organisms live
d. ecosystem—energy flow and chemical cycling occur
2. Distribution of organisms tends to be
a. clumped, random, or uniform.
b. determined by environmental factors.
c. the same as the population density.
d. Both a and b are correct.
3. If the birthrate is 10 per 1,000 and the death rate
is 10 per 1,000, then the growth rate is
a. 0.
b. 10.
c. 20.
d. 100.
4. If the growth rate is positive, then
a. population growth will occur.
b. the size of the population will increase.
c. environmental conditions will eventually oppose further increase.
d. All of these are correct.
5. During exponential growth, growth
a. remains steady.
b. is accelerating.
c. is declining.
d. depends on the environment.
6. Survivorship in a population is related to
a. age of death.
b. biotic potential.
c. age structure diagram.
d. All of these are correct.
7. If the survivorship curve is a straight diagonal line,
then
a. the rate of death is constant, regardless of age.
b. most individuals live out the expected life
span.
c. most individuals die early.
d. environmental resistance has occurred.
8. Select the density-dependent effect.
a. climate
b. predation
c. natural disaster
d. weather
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9. Density-dependent effects
a. increase as density increases.
b. tend to be biotic factors.
c. tend to be abiotic factors.
d. Both a and b are correct.
10. The countries in Asia and Africa are
a. MDCs experiencing rapid growth.
b. LDCs experiencing rapid growth.
c. MDCs experiencing slow growth.
d. LDCs experiencing slow growth.
11. The doubling time for the world’s population
will most likely
a. always remain the same.
b. become longer because of demographic
transition.
c. become shorter and shorter regardless.
d. fluctuate because of depressions.
12. Which is true of exponential growth?
a. represents the logistic growth pattern
b. does not usually occur for long in nature
c. is seen in populations that have an equilibrium life history pattern
d. Both b and c are correct.
13. Which of the following is mismatched?
a. community—several populations interacting
b. ecosystem—community interacting with its
physical environment
c. populations—all the individuals of the same
species in an area
d. biosphere—portion of Earth’s surface where
living things exist
e. All of these are correct.
14. Populations with an equilibrium life history pattern tend to have a(n) ______________ growth
curve.
a. exponential
b. logistic
15. Competition is an example of
a. a density-independent effect.
b. a density-dependent effect.
c. a biotic effect.
d. population size.
e. Both b and c are correct.
16. Which of these does not contribute to biotic potential?
a. number of reproductive events a year
b. survivorship curve
c. number of offspring per reproduction
d. competition ability
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17. Which of these is not characteristic of an opportunistic population?
a. regulated by density-dependent effects
b. exponential growth
c. low biotic potential
d. exceeds carrying capacity
e. good dispersal techniques
18. The logistic growth pattern
a. has a stable equilibrium phase.
b. does not have a stable equilibrium phase.
c. has a lag phase.
d. has an exponential growth phase.
19. Which of these does NOT describe a population
with a high biotic potential?
a. starts reproduction at an early age
b. Young usually survive until reproduction.
c. reproduce every several years
d. has a large number of offspring
20. Which of these does NOT describe a MDC?
a. more industrialized
b. Age structure diagram resembles a pyramid.
c. have undergone the demographic transition
d. uses more resources
CRITICAL THINKING QUESTIONS
The introduction to this chapter is about human populations.
21. Some people believe that we need not control population because one day we will be able to have people
colonize space. Why might this be an impractical suggestion? _______________________________________________
22. As the human population increases, there is less land available for agriculture. Why is this a problem? _______
_____________________________________________________________________________________________________________
23. As more countries become industrialized, they will use more resources that cause pollution. Why is this a
concern? ___________________________________________________________________________________________________
24. Most of the world’s population live in cities. How might it be possible for cities to be more self-sustaining? __
_____________________________________________________________________________________________________________
Test Results: ______ number correct ÷ 24 = ______ × 100 = ______ %
EXPLORING
THE
INTERNET
ARIS, the Essentials of Biology website: http://www.mhhe.com/maderessentials
ARIS, the website for Essentials of Biology, offers access to a wide variety of tools to help students learn biological
concepts and to reinforce their knowledge. Online study aids such as practice quizzes, interactive activities, animations, labeling exercises, flashcards, and much more are organized according to the major sections of each chapter.
There is even an online tutorial service!
ANSWER
CHAPTER KEY TERMS
a. ecology b. age structure c. survivorship d. life
history e. community f. density-dependent factor
g. density-independent factor h. biotic potential i. resource
j. exponential growth k. population l. logistic growth
m. extinction n. carrying capacity o. demographics
p. ecosystem
KEY
STUDY EXERCISES
1. c 2. d 3. e 4. c 5. a. 25 years b. twice as many
6. a. MDC b. LDC c. LDC d. MDC e. LDC f. MDC
7. a. A couple has two children. b. where there are as many
women entering the reproductive years as those leaving
them behind c. MDCs 8. MDCs 9. a. uniform
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b. random c. clumped 10. a. .06 b. .04 c. .02 d. 51
11. a. increasing population b. decreasing population
c. stable population d. b, Reproductive years are greater
than prereproductive years e. a, Prereproductive years
are greater than reproductive. 12. a. II b. III c. I
13. resources 14. a. early b. survived until reproduction
c. few months d. large 15 a. ep b. lg 16. both (see Figures 30.10 and 30.11, pp. 540–541, in text) 17. both
18. a. slow b. accelerating 19. b 20. b 21. exponential 22. a. resources b. population c. carrying capacity 23. a. DD b. DI c. DD d. DI 24. a. decreases
b. predation 25. a. EP b. OP c. EP d. OP e. EP f. OP
g. EP h. OP i. EP 26. a. community b. ecosystem
c. population d. biosphere e. population f. community
KEYWORD CROSSWORD
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CHAPTER TEST
1. b 2. d 3. a 4. d 5. b 6. a 7. a 8. b 9. d
10. b 11. b 12. b 13. e 14. b 15. e 16. d 17. c
18. a 19. c 20. b 21. The amount of energy, funds,
and technology may never be available to have people go
and live on other planets. 22. We have to grow more food
on less land. 23. Pollution is a threat to the continued
existence of the human population. 24. Use less nonrenewable energy and/or use renewable energy and recycle
materials.