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Chapter 36
0
Population Ecology
PowerPoint Lectures for
Biology: Concepts & Connections, Sixth Edition Campbell, Reece, Taylor, Simon, and Dickey
Lecture by Brian R. Shmaefsky Copyright © 2009 Pearson Education, Inc.
Introduction: A Tale of Two Fishes Population ecology is concerned with – Changes in population size – Factors that regulate populations over time
It helps explain the biodiversity of an environment
Copyright © 2009 Pearson Education, Inc.
0
Introduction: A Tale of Two Fishes
0
Ecologists learn the structure and dynamics of natural populations With this information they are better equipped to – Develop sustainable food sources – Assess the impact of human activities – Balance human needs with the conservation of biodiversity and resources
Copyright © 2009 Pearson Education, Inc.
36.1 Population ecology is the study of how and0 why populations change Population – A group of individuals of a single species that occupy the same general area
Individuals in a population – Rely on the same resources – Are influenced by the same environmental factors – Are likely to interact and breed with one another
Copyright © 2009 Pearson Education, Inc.
36.1 Population ecology is the study of how and0 why populations change A population can be described by the number and distribution of individuals Population dynamics is the interactions between – Biotic and abiotic factors
It is the cause of variation in population sizes – A population increases through birth and immigration – Death and emigration out of an area decrease the population Copyright © 2009 Pearson Education, Inc.
36.2 Density and dispersion patterns are important population variables
0
Population density is the number of individuals of a species per unit area or volume Examples of population density – The number of oak trees per square kilometer in a forest – The number of earthworms per cubic meter in forest soil
Ecologists use a variety of sampling techniques to estimate population densities Copyright © 2009 Pearson Education, Inc.
36.2 Density and dispersion patterns are important population variables
0
Within a population’s geographic range, local densities may vary greatly The dispersion pattern of a population refers to the way individuals are spaced within their area
Video: Flapping Geese (clumped) Video: Albatross Courtship (uniform)
Video: Prokaryotic Flagella (Salmonella typhimurium) (random) Copyright © 2009 Pearson Education, Inc.
0
36.2 Density and dispersion patterns are important population variables
0
The dispersion pattern of a population refers to the way individuals are spaced within their area Dispersion patterns can be – Clumped – Uniform – Random
Copyright © 2009 Pearson Education, Inc.
36.2 Density and dispersion patterns are important population variables In a clumped pattern individuals are grouped in patches
Copyright © 2009 Pearson Education, Inc.
0
36.2 Density and dispersion patterns are important population variables
0
In a uniform pattern individuals are equally spaced in the environment
Copyright © 2009 Pearson Education, Inc.
0
36.2 Density and dispersion patterns are important population variables In a random pattern of dispersion, the individuals in a population are spaced in an unpredictable way
Copyright © 2009 Pearson Education, Inc.
0
0 36. 3 Life tables track survivorship in populations
Life tables track survivorship over the life span of individuals in a population Survivorship curves plot the proportion of individuals alive at each age – Type I – Type II – Type III
Copyright © 2009 Pearson Education, Inc.
Percentage of survivors (log scale)
100
I
10 II 1 III 0.1 0
50 Percentage of maximum life span
100
36.4 Idealized models predict patterns of population growth Exponential growth model – The rate of population increases under ideal conditions – Calculated using the equation G = rN – G is the growth rate of the population – N is the population size – r is the per capita rate of increase
Copyright © 2009 Pearson Education, Inc.
0
500
Population size (N)
450 400 350 300 250 200 150 100 50 0 0 1 2 3 4 5 6 7 8 9 10 11 12 Time (months)
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
Copyright © 2009 Pearson Education, Inc.
(K − N) G = rN K
0
Breeding male fur seals (thousands) 10 8
6
4
2
0 1915 1925 1935 1945 Year
36.4 Idealized models predict patterns of population growth Idealized models describe two kinds of population growth – Exponential growth – Logistic growth
Copyright © 2009 Pearson Education, Inc.
0
Number of individuals (N)
G = rN K
0
G = rN
Time
(K – N) K
0 36.5 Multiple factors may limit population growth
The logistic growth model – Population growth slows and ceases as population density increases – Increasing population density results in a decrease in birth rate, an increase in death rate, or both
Copyright © 2009 Pearson Education, Inc.
4.0
Clutch size
3.8 3.6 3.4 3.2 3.0 2.8
0
10
20
50 40 60 30 Density of females
70
80
0 36.5 Multiple factors may limit population growth
Abiotic factors may reduce population size before other limiting factors become important
Copyright © 2009 Pearson Education, Inc.
Number of aphids
Exponential growth
Apr
May Jun
Sudden decline
Jul
Aug Sep
Oct Nov Dec
0 36.5 Multiple factors may limit population growth
Most populations fluctuate in numbers
Copyright © 2009 Pearson Education, Inc.
Number of females
80
60
40
20
0
1975
1980
1985 1990 Time (years)
1995
2000
36.6 Some populations have “boom-and-bust” cycles Some populations fluctuate in density with regularity Boom-and-bust cycles – Food shortages – Predator-prey interactions
Copyright © 2009 Pearson Education, Inc.
0
Hare population size (thousands) 160
120 Lynx
80 6
40 3
0 0
1850 1875 1900 Year 9
1925
Lynx population size (thousands)
Snowshoe hare
36.7 EVOLUTION CONNECTION: Evolution 0 shapes life histories Life history – Series of events from birth to death
r/K selection – r-selective traits – K-selective traits
Copyright © 2009 Pearson Education, Inc.
Experimental transplant of guppies Predator: Killifish; preys mainly on small guppies
Pools with killifish, but no guppies prior to transplant
Guppies: Larger at sexual maturity than those in pike-cichlid pools
Predator: Pike-cichlid preys mainly on large guppies Guppies: Smaller at sexual maturity than those in killifish pools
200 160 120 80 40
185.6 161.5 67.5 76.1
Males
Females
Age of guppies at maturity (days)
Mass of guppies at maturity (mg)
11 years later 100 80 60 40 20
85.7 92.3 48.5
58.2
Males
Females
Control: Guppies from pools with pike-cichlids as predators Experimental: Guppies transplanted to pools with killifish as predators
Experimental transplant of guppies Predator: Killifish; preys mainly on small guppies
Pools with killifish, but no guppies prior to transplant
Guppies: Larger at sexual maturity than those in pike-cichlid pools
Predator: Pike-cichlid preys mainly on large guppies Guppies: Smaller at sexual maturity than those in killifish pools
200 160 120 80 40
161.5
185.6
67.5 76.1
Males
Females
Age of guppies at maturity (days)
Mass of guppies at maturity (mg)
11 years later
100 80 60 40 20
85.7 92.3 48.5
58.2
Males
Females
Control: Guppies from pools with pike-cichlids as predators Experimental: Guppies transplanted to pools with killifish as predators
36.8 CONNECTION: Principles of population ecology have practical applications Sustainable resource management – Maximum sustained yield
Copyright © 2009 Pearson Education, Inc.
0
Yield (thousands of metric tons)
900 800 700 600 500 400 300 200 100 0
1960
1970
1980
1990
2000
0 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
Copyright © 2009 Pearson Education, Inc.
80
10 Population increase
8
60
6
40
4 Total population size
20
1500 1550 1600 1650 1700 1750 1800 1850 1900 1950 2000 2050 Year
2 0
Total population (in billions)
Annual increase (in millions)
100
Birth or death rate per 1,000 population
50 40 30 20 10
Rate of increase (r)
Birth rate Death rate
0 1900
1925
1950
1975
Year
2000
2025
2050
0 36.9 The human population continues to increase, but the growth rate is slowing
Population momentum of Mexico
Copyright © 2009 Pearson Education, Inc.
Age 80+ 75-79 70-74 65-69 60-64 55-59 50-54 45-49 40-44 35-39 30-34 25-29 20-24 15-19 10-14 5-9 0-4
2005
1980 Male
5
4
Male
Female
3 2 1 0 1 2 3 4 5 Population in millions Total population size = 68,347,479
5
4
2030 Female
3 2 1 0 1 2 3 4 5 Population in millions Total population size = 106,202,903
Male
5
4
Female
3 2 1 0 1 2 3 4 5 Population in millions Total population size = 135,172,155
Age 80+ 75-79 70-74 65-69 60-64 55-59 50-54 45-49 40-44 35-39 30-34 25-29 20-24 15-19 10-14 5-9 0-4
1980 Male
5
Female
3 2 1 0 1 2 3 4 5 Population in millions Total population size = 68,347,479 4
Age 80+ 75-79 70-74 65-69 60-64 55-59 50-54 45-49 40-44 35-39 30-34 25-29 20-24 15-19 10-14 5-9 0-4
2005 Male
Female
3 2 1 0 1 2 3 4 5 Population in millions Total population size = 106,202,903
5
4
Age 80+ 75-79 70-74 65-69 60-64 55-59 50-54 45-49 40-44 35-39 30-34 25-29 20-24 15-19 10-14 5-9 0-4
2030 Male
Female
3 2 1 0 1 2 3 4 5 Population in millions Total population size = 135,172,155
5
4
36.10 CONNECTION: Age structures reveal social and economic trends Age structure diagram – Reveals a population’s growth trends
Copyright © 2009 Pearson Education, Inc.
0
1980 Age Birth years Male Female 80+ before 1900 75-79 1901-1905 70-74 1906-10 65-69 1911-15 1916-20 60-64 55-59 1921-25 50-54 1926-30 1931-35 45-49 1936-40 40-44 1941-45 35-39 1946-50 30-34 25-29 1951-55 20-24 1956-60 15-19 1961-65 1966-70 10-14 1971-75 5-9 1976-80 0-4 12 10 8 6 4 2 0 2 4 6 8 10 12 Population in millions Total population size = 227,726,463
2005 Birth years Male Female before 1926 1926-30 1931-35 1936-40 1941-45 1946-50 1951-55 1956-60 1961-65 1966-70 1971-75 1976-80 1981-85 1986-90 1991-95 1996-2000 2001-2005 12 10 8 6 4 2 0 2 4 6 8 10 12 Population in millions Total population size = 295,734,134
Birth years before 1951 1951-55 1956-60 1961-65 1966-70 1971-75 1976-80 1981-85 1986-90 1991-95 1996-2000 2001-05 2006-10 2011-15 2016-20 2021-25 2026-30
2030 Male Female
12 10 8 6 4 2 0 2 4 6 8 10 12 Population in millions Total population size = 363,811,435
0 a 36.11 CONNECTION: An ecological footprint is measure of resource consumption
U.S. Census Bureau projection – 8 billion people within the next 20 years – 9.5 billion by mid-21st century
Copyright © 2009 Pearson Education, Inc.
0 a 36.11 CONNECTION: An ecological footprint is measure of resource consumption
Ecological footprint helps understand resource availability and usage The United States has a – Big ecological footprint – Large ecological deficit
Copyright © 2009 Pearson Education, Inc.
You should now be able to
0
1. Explain the factors that determine the characteristics of a population 2. Describe exponential growth and the factors that produce logistic growth of a population 3. Explain the limiting factors that influence population growth 4. Distinguish between r- and K-strategies 5. Describe and give examples of the different types of life histories Copyright © 2009 Pearson Education, Inc.
You should now be able to
0
6. Explain the factors the determine human population growth 7. Describe the concept of ecological footprint
Copyright © 2009 Pearson Education, Inc.
0
Population Ecology
PowerPoint Lectures for
Biology: Concepts & Connections, Sixth Edition Campbell, Reece, Taylor, Simon, and Dickey
Lecture by Brian R. Shmaefsky Copyright © 2009 Pearson Education, Inc.
Introduction: A Tale of Two Fishes Population ecology is concerned with – Changes in population size – Factors that regulate populations over time
It helps explain the biodiversity of an environment
Copyright © 2009 Pearson Education, Inc.
0
Introduction: A Tale of Two Fishes
0
Ecologists learn the structure and dynamics of natural populations With this information they are better equipped to – Develop sustainable food sources – Assess the impact of human activities – Balance human needs with the conservation of biodiversity and resources
Copyright © 2009 Pearson Education, Inc.
36.1 Population ecology is the study of how and0 why populations change Population – A group of individuals of a single species that occupy the same general area
Individuals in a population – Rely on the same resources – Are influenced by the same environmental factors – Are likely to interact and breed with one another
Copyright © 2009 Pearson Education, Inc.
36.1 Population ecology is the study of how and0 why populations change A population can be described by the number and distribution of individuals Population dynamics is the interactions between – Biotic and abiotic factors
It is the cause of variation in population sizes – A population increases through birth and immigration – Death and emigration out of an area decrease the population Copyright © 2009 Pearson Education, Inc.
36.2 Density and dispersion patterns are important population variables
0
Population density is the number of individuals of a species per unit area or volume Examples of population density – The number of oak trees per square kilometer in a forest – The number of earthworms per cubic meter in forest soil
Ecologists use a variety of sampling techniques to estimate population densities Copyright © 2009 Pearson Education, Inc.
36.2 Density and dispersion patterns are important population variables
0
Within a population’s geographic range, local densities may vary greatly The dispersion pattern of a population refers to the way individuals are spaced within their area
Video: Flapping Geese (clumped) Video: Albatross Courtship (uniform)
Video: Prokaryotic Flagella (Salmonella typhimurium) (random) Copyright © 2009 Pearson Education, Inc.
0
36.2 Density and dispersion patterns are important population variables
0
The dispersion pattern of a population refers to the way individuals are spaced within their area Dispersion patterns can be – Clumped – Uniform – Random
Copyright © 2009 Pearson Education, Inc.
36.2 Density and dispersion patterns are important population variables In a clumped pattern individuals are grouped in patches
Copyright © 2009 Pearson Education, Inc.
0
36.2 Density and dispersion patterns are important population variables
0
In a uniform pattern individuals are equally spaced in the environment
Copyright © 2009 Pearson Education, Inc.
0
36.2 Density and dispersion patterns are important population variables In a random pattern of dispersion, the individuals in a population are spaced in an unpredictable way
Copyright © 2009 Pearson Education, Inc.
0
0 36. 3 Life tables track survivorship in populations
Life tables track survivorship over the life span of individuals in a population Survivorship curves plot the proportion of individuals alive at each age – Type I – Type II – Type III
Copyright © 2009 Pearson Education, Inc.
Percentage of survivors (log scale)
100
I
10 II 1 III 0.1 0
50 Percentage of maximum life span
100
36.4 Idealized models predict patterns of population growth Exponential growth model – The rate of population increases under ideal conditions – Calculated using the equation G = rN – G is the growth rate of the population – N is the population size – r is the per capita rate of increase
Copyright © 2009 Pearson Education, Inc.
0
500
Population size (N)
450 400 350 300 250 200 150 100 50 0 0 1 2 3 4 5 6 7 8 9 10 11 12 Time (months)
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
Copyright © 2009 Pearson Education, Inc.
(K − N) G = rN K
0
Breeding male fur seals (thousands) 10 8
6
4
2
0 1915 1925 1935 1945 Year
36.4 Idealized models predict patterns of population growth Idealized models describe two kinds of population growth – Exponential growth – Logistic growth
Copyright © 2009 Pearson Education, Inc.
0
Number of individuals (N)
G = rN K
0
G = rN
Time
(K – N) K
0 36.5 Multiple factors may limit population growth
The logistic growth model – Population growth slows and ceases as population density increases – Increasing population density results in a decrease in birth rate, an increase in death rate, or both
Copyright © 2009 Pearson Education, Inc.
4.0
Clutch size
3.8 3.6 3.4 3.2 3.0 2.8
0
10
20
50 40 60 30 Density of females
70
80
0 36.5 Multiple factors may limit population growth
Abiotic factors may reduce population size before other limiting factors become important
Copyright © 2009 Pearson Education, Inc.
Number of aphids
Exponential growth
Apr
May Jun
Sudden decline
Jul
Aug Sep
Oct Nov Dec
0 36.5 Multiple factors may limit population growth
Most populations fluctuate in numbers
Copyright © 2009 Pearson Education, Inc.
Number of females
80
60
40
20
0
1975
1980
1985 1990 Time (years)
1995
2000
36.6 Some populations have “boom-and-bust” cycles Some populations fluctuate in density with regularity Boom-and-bust cycles – Food shortages – Predator-prey interactions
Copyright © 2009 Pearson Education, Inc.
0
Hare population size (thousands) 160
120 Lynx
80 6
40 3
0 0
1850 1875 1900 Year 9
1925
Lynx population size (thousands)
Snowshoe hare
36.7 EVOLUTION CONNECTION: Evolution 0 shapes life histories Life history – Series of events from birth to death
r/K selection – r-selective traits – K-selective traits
Copyright © 2009 Pearson Education, Inc.
Experimental transplant of guppies Predator: Killifish; preys mainly on small guppies
Pools with killifish, but no guppies prior to transplant
Guppies: Larger at sexual maturity than those in pike-cichlid pools
Predator: Pike-cichlid preys mainly on large guppies Guppies: Smaller at sexual maturity than those in killifish pools
200 160 120 80 40
185.6 161.5 67.5 76.1
Males
Females
Age of guppies at maturity (days)
Mass of guppies at maturity (mg)
11 years later 100 80 60 40 20
85.7 92.3 48.5
58.2
Males
Females
Control: Guppies from pools with pike-cichlids as predators Experimental: Guppies transplanted to pools with killifish as predators
Experimental transplant of guppies Predator: Killifish; preys mainly on small guppies
Pools with killifish, but no guppies prior to transplant
Guppies: Larger at sexual maturity than those in pike-cichlid pools
Predator: Pike-cichlid preys mainly on large guppies Guppies: Smaller at sexual maturity than those in killifish pools
200 160 120 80 40
161.5
185.6
67.5 76.1
Males
Females
Age of guppies at maturity (days)
Mass of guppies at maturity (mg)
11 years later
100 80 60 40 20
85.7 92.3 48.5
58.2
Males
Females
Control: Guppies from pools with pike-cichlids as predators Experimental: Guppies transplanted to pools with killifish as predators
36.8 CONNECTION: Principles of population ecology have practical applications Sustainable resource management – Maximum sustained yield
Copyright © 2009 Pearson Education, Inc.
0
Yield (thousands of metric tons)
900 800 700 600 500 400 300 200 100 0
1960
1970
1980
1990
2000
0 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
Copyright © 2009 Pearson Education, Inc.
80
10 Population increase
8
60
6
40
4 Total population size
20
1500 1550 1600 1650 1700 1750 1800 1850 1900 1950 2000 2050 Year
2 0
Total population (in billions)
Annual increase (in millions)
100
Birth or death rate per 1,000 population
50 40 30 20 10
Rate of increase (r)
Birth rate Death rate
0 1900
1925
1950
1975
Year
2000
2025
2050
0 36.9 The human population continues to increase, but the growth rate is slowing
Population momentum of Mexico
Copyright © 2009 Pearson Education, Inc.
Age 80+ 75-79 70-74 65-69 60-64 55-59 50-54 45-49 40-44 35-39 30-34 25-29 20-24 15-19 10-14 5-9 0-4
2005
1980 Male
5
4
Male
Female
3 2 1 0 1 2 3 4 5 Population in millions Total population size = 68,347,479
5
4
2030 Female
3 2 1 0 1 2 3 4 5 Population in millions Total population size = 106,202,903
Male
5
4
Female
3 2 1 0 1 2 3 4 5 Population in millions Total population size = 135,172,155
Age 80+ 75-79 70-74 65-69 60-64 55-59 50-54 45-49 40-44 35-39 30-34 25-29 20-24 15-19 10-14 5-9 0-4
1980 Male
5
Female
3 2 1 0 1 2 3 4 5 Population in millions Total population size = 68,347,479 4
Age 80+ 75-79 70-74 65-69 60-64 55-59 50-54 45-49 40-44 35-39 30-34 25-29 20-24 15-19 10-14 5-9 0-4
2005 Male
Female
3 2 1 0 1 2 3 4 5 Population in millions Total population size = 106,202,903
5
4
Age 80+ 75-79 70-74 65-69 60-64 55-59 50-54 45-49 40-44 35-39 30-34 25-29 20-24 15-19 10-14 5-9 0-4
2030 Male
Female
3 2 1 0 1 2 3 4 5 Population in millions Total population size = 135,172,155
5
4
36.10 CONNECTION: Age structures reveal social and economic trends Age structure diagram – Reveals a population’s growth trends
Copyright © 2009 Pearson Education, Inc.
0
1980 Age Birth years Male Female 80+ before 1900 75-79 1901-1905 70-74 1906-10 65-69 1911-15 1916-20 60-64 55-59 1921-25 50-54 1926-30 1931-35 45-49 1936-40 40-44 1941-45 35-39 1946-50 30-34 25-29 1951-55 20-24 1956-60 15-19 1961-65 1966-70 10-14 1971-75 5-9 1976-80 0-4 12 10 8 6 4 2 0 2 4 6 8 10 12 Population in millions Total population size = 227,726,463
2005 Birth years Male Female before 1926 1926-30 1931-35 1936-40 1941-45 1946-50 1951-55 1956-60 1961-65 1966-70 1971-75 1976-80 1981-85 1986-90 1991-95 1996-2000 2001-2005 12 10 8 6 4 2 0 2 4 6 8 10 12 Population in millions Total population size = 295,734,134
Birth years before 1951 1951-55 1956-60 1961-65 1966-70 1971-75 1976-80 1981-85 1986-90 1991-95 1996-2000 2001-05 2006-10 2011-15 2016-20 2021-25 2026-30
2030 Male Female
12 10 8 6 4 2 0 2 4 6 8 10 12 Population in millions Total population size = 363,811,435
0 a 36.11 CONNECTION: An ecological footprint is measure of resource consumption
U.S. Census Bureau projection – 8 billion people within the next 20 years – 9.5 billion by mid-21st century
Copyright © 2009 Pearson Education, Inc.
0 a 36.11 CONNECTION: An ecological footprint is measure of resource consumption
Ecological footprint helps understand resource availability and usage The United States has a – Big ecological footprint – Large ecological deficit
Copyright © 2009 Pearson Education, Inc.
You should now be able to
0
1. Explain the factors that determine the characteristics of a population 2. Describe exponential growth and the factors that produce logistic growth of a population 3. Explain the limiting factors that influence population growth 4. Distinguish between r- and K-strategies 5. Describe and give examples of the different types of life histories Copyright © 2009 Pearson Education, Inc.
You should now be able to
0
6. Explain the factors the determine human population growth 7. Describe the concept of ecological footprint
Copyright © 2009 Pearson Education, Inc.
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