Transcript Population Ecology

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Ecology - Study of interactions among organisms and their
environment
Conservation biology, environmentalism:
preservation of natural world
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Biosphere
• Ecosystems
ECOSYSTEM LEVEL
Eucalyptus forest
COMMUNITY LEVEL
All organisms in
eucalyptus forest
• Community
• Population
POPULATION LEVEL
Group of flying foxes
ORGANISM LEVEL
Flying fox
Brain
ORGAN SYSTEM LEVEL
Nervous system
ORGAN LEVEL
Brain
Spinal cord
Nerve
TISSUE LEVEL
Nervous
tissue
CELLULAR LEVEL
Nerve cell
MOLECULAR LEVEL
Molecule of DNA
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Figure 1.1
Population Ecology
• Population- how to measure?
• Growth rates: J shaped, S shaped
• K, r, and reproductive strategies
• Human population
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How are populations measured?
• Population density = number of individuals in
a given area or volume
• count all the individuals in a population
• estimate by sampling
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• mark-recapture method depends on likelihood
of recapturing the same individual
Figure 35.2A
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• The dispersion pattern of a population refers
to the way individuals are spaced within
their area
– Clumped – Uniform:
– Random: no pattern
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Figure 35.2C
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How do populations grow?
• Idealized models describe two kinds of
population growth
1. exponential growth
2. logistic growth
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• King’s chess game
• A J-shaped growth curve, described by the
equation G = rN, is typical of exponential
growth
– G = the population growth rate
– r = the intrinsic rate of increase, or an
organism's maximum capacity to reproduce
– N = the population size
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Figure 35.3A
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high intrinsic
rate of increase
1500
Population size
1000
low intrinsic
rate of increase
500
r=0
zero population
growth
negative intrinsic
rate of increase
r = -0.05
0
0
5
10
Time (years)
15
20
2. Logistic growth is slowed by populationlimiting factors
K = Carrying capacity is
the maximum
population size
that an environment
can support
Figure 35.3B
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• logistic growth curve
– K = carrying capacity
– The term
(K - N)/K
accounts
for the
leveling
off of the
curve
Figure 35.3C
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Multiple factors may limit population growth
declining birth rate or increasing death rate
• The regulation of growth in a natural
population is determined by several factors
– limited food supply
– the buildup of toxic wastes
– increased disease
– predation
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– About every 10 years, both hare and lynx
populations have a rapid increase (a "boom")
followed by a sharp decline (a "bust")
Figure 35.5
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• Survivorship curves plot the proportion of
individuals alive at each age
• Three types of survivorship curves reflect
important species differences in life history
Figure 35.6
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Evolution shapes life histories
• An organism's life history is the series of events
from birth through reproduction to death
• Life history traits include
– the age at which reproduction first occurs
– the frequency of reproduction
– the number of offspring
– the amount of parental care given
– the energy cost of reproduction
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• Principles of population ecology may be used
to
– manage wildlife, fisheries, and forests for
sustainable yield
– reverse the decline of threatened or
endangered species
– reduce pest populations
– IPM = Integrated Pest Management
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• Integrated pest management (IPM) uses a
combination of biological, chemical, and
cultural methods to control agricultural pests
• IPM relies on knowledge of
–the population ecology of the pest
–its associated predators and parasites
–crop growth dynamics
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The Spread of Shakespeare's Starlings
• In 1890, a group of Shakespeare enthusiasts
released about 120 starlings in New York's
Central Park
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• Today: over 100 million starlings, spread over
N. Amer.
Current
1955
Current
1955
1945
1935
1925
1945
1905
1915
1935
1925
1925
1935
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• The starling population in North America has
some features in common with the global
human population
– Both are expanding and are virtually
uncontrolled
– Both are harming other species
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THE HUMAN POPULATION
• doubled three times in the last three centuries
• about 6.1 billion and may reach 9.3 billion by
the year 2050
• improved health and technology have lowered
death rates
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• The history of human population growth
Figure 35.8A
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• The age structure of a population is the proportion
of individuals in different age-groups
RAPID GROWTH
SLOW GROWTH
ZERO GROWTH/DECREASE
Kenya
United States
Italy
Male
Female
Male
Female
Ages 45+
Ages 45+
Ages 15–44
Ages 15–44
Under
15
Percent of population
Male
Female
Under
15
Percent of population
Percent of population
Also reveals social conditions, status of women
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Figure 35.9B
• The ecological footprint represents the
amount of productive land needed to support a
nation’s resource needs
• The ecological capacity of the world may
already be smaller than its ecological
footprint
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• Ecological footprint in relation to ecological
capacity
Figure 35.8B
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Per capita CO2 emissions
(metric tons of carbon)
0
1
2
3
U.S.
China
5
6
5.48
2.65
Japan
2.51
0.29
0
0.5
1
U.S.
Russia
Japan
India
1.5
1.49
China
0.75
Russia
India
4
Total CO2 emissions
(billion metric tons of carbon)
0.91
0.39
0.32
0.28
• What next?
Figure 35.8C
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Figure 2.10x
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