Transcript Introduction to Ecology

Biology, Seventh Edition
Solomon • Berg • Martin
Chapter 51
Introduction to Ecology:
Population Ecology
Copyright © 2005 Brooks/Cole — Thomson Learning
Biology, Seventh Edition
CHAPTER 51 Introduction to Ecology: Population Ecology
• Population density
• Number of individuals of a species
per unit at a given time
• Population dispersion (spacing)
• Clumped dispersion
• Uniform dispersion
• Random dispersion
Copyright © 2005 Brooks/Cole — Thomson Learning
Biology, Seventh Edition
CHAPTER 51 Introduction to Ecology: Population Ecology
Dispersion of
individuals with a
population
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Biology, Seventh Edition
CHAPTER 51 Introduction to Ecology: Population Ecology
Dispersion in a sand pine population in
Florida
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Biology, Seventh Edition
CHAPTER 51 Introduction to Ecology: Population Ecology
• Four factors that produce
changes in population size
• Natality
• Mortality
• Immigration
• Emigration
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Biology, Seventh Edition
CHAPTER 51 Introduction to Ecology: Population Ecology
• Intrinsic rate of increase (rmax)
• Maximum rate at which species or
population can increase under ideal
conditions
• Carrying capacity (K) is the largest
population that can be maintained
–Exponential population growth (Jshaped curve)
–Logistic population curve (S-shaped
curve)
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Biology, Seventh Edition
CHAPTER 51 Introduction to Ecology: Population Ecology
Exponential population growth
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Biology, Seventh Edition
CHAPTER 51 Introduction to Ecology: Population Ecology
Carrying capacity and logistic population
growth
Copyright © 2005 Brooks/Cole — Thomson Learning
Biology, Seventh Edition
CHAPTER 51 Introduction to Ecology: Population Ecology
• Density-dependent factors
• Regulate population growth by
affecting a large proportion of the
population as population rises
• Examples include predation,
disease, and competition
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Biology, Seventh Edition
CHAPTER 51 Introduction to Ecology: Population Ecology
Density-dependent factors and
negative feedback
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Biology, Seventh Edition
CHAPTER 51 Introduction to Ecology: Population Ecology
• Density-independent factors
• Limit population growth but are not
influenced by changes in
population density
• Examples include hurricanes and
blizzards
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Biology, Seventh Edition
CHAPTER 51 Introduction to Ecology: Population Ecology
• Semelparous reproduction
• Expend their energy in a single,
immense reproductive effort
• Iteroparous reproduction
• Exhibit repeated reproductive
cycles throughout their lifetimes
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Biology, Seventh Edition
CHAPTER 51 Introduction to Ecology: Population Ecology
Semelparity
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Biology, Seventh Edition
CHAPTER 51 Introduction to Ecology: Population Ecology
• Species exhibiting an r strategy
• Emphasizes a high growth rate
• Organisms typically have small
body size, high reproductive rates,
short life spans, and they inhabit
variable environments
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Biology, Seventh Edition
CHAPTER 51 Introduction to Ecology: Population Ecology
• Species exhibiting a K strategy
• Maintains a population near the
carrying capacity of the
environment
• Species often have large body size,
low reproductive rates, long life
spans, and they inhabit stable
environments
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Biology, Seventh Edition
CHAPTER 51 Introduction to Ecology: Population Ecology
• Survivorship curves
• Type I
–Mortality is greatest in old age
• Type II
–Mortality is spread evenly across all
ages
• Type III
–Mortality is greatest among the young
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Biology, Seventh Edition
CHAPTER 51 Introduction to Ecology: Population Ecology
Survivorship curves
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Biology, Seventh Edition
CHAPTER 51 Introduction to Ecology: Population Ecology
Survivorship
curve for
a herring
gull
population
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Biology, Seventh Edition
CHAPTER 51 Introduction to Ecology: Population Ecology
• Source habitats
• Preferred habitats
• Local reproductive success is
greater than local mortality
• Local individuals disperse from
source habitats
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Biology, Seventh Edition
CHAPTER 51 Introduction to Ecology: Population Ecology
• Sink habitats
• Lower-quality habitats
• Individuals may suffer death or
poor reproductive success
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Biology, Seventh Edition
CHAPTER 51 Introduction to Ecology: Population Ecology
Source and sink populations in a
hypothetical metapopulation
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Biology, Seventh Edition
CHAPTER 51 Introduction to Ecology: Population Ecology
• Human population growth
• World population reached 6.3
billion in 2003
• Per capita growth rate has declined
from peak in 1965 of about 2% per
year to 1.3%
• Scientists predict zero population
growth by the end of the 21st
century
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Biology, Seventh Edition
CHAPTER 51 Introduction to Ecology: Population Ecology
Human population growth
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Biology, Seventh Edition
CHAPTER 51 Introduction to Ecology: Population Ecology
• Population characteristics
• Highly developed countries
–Low birth rate, low infant mortality, low
fertility rate, long life expectancies,
and high GNI PPP
• Developing countries
–High birth rate, high infant mortality,
high fertility rate, short life
expectancies, and low GNI PPP
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Biology, Seventh Edition
CHAPTER 51 Introduction to Ecology: Population Ecology
Comparison of 2003 population data in
developed and developing countries
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Biology, Seventh Edition
CHAPTER 51 Introduction to Ecology: Population Ecology
Birth and death rates in Mexico, 1900–2000
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Biology, Seventh Edition
CHAPTER 51 Introduction to Ecology: Population Ecology
• Age structure influences
dynamics
• Possible for country to have
replacement-level fertility and still
experience population growth
• Young age structure causes a
positive population growth
momentum as large
prereproductive age group matures
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Biology, Seventh Edition
CHAPTER 51 Introduction to Ecology: Population Ecology
Age structure diagrams
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Biology, Seventh Edition
CHAPTER 51 Introduction to Ecology: Population Ecology
• Developing countries tend to
have people overpopulation that
degrades the environment
• Developed countries have
consumption overpopulation that
degrades the environment
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