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Population Ecology

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Population Ecology * Although several species may share a habitat they each have their own niche. A niche is a very narrow range where a species fits within a habitat. – PowerPoint PPT presentation

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Title: Population Ecology


1
Population Ecology
2
Population Dynamics
  • Population
  • All the individuals of a species that live
    together in an area

3
Population Dynamics
  • Three Key Features of Populations
  • Size
  • Density
  • Dispersion

4
  • Three Key Features of Populations

Size number of individuals in an area
5
Three Key Features of Populations
  • Growth Rate
  • Birth Rate (natality) - Death Rate (mortality)
  • How many individuals are born vs. how many die
  • Birth rate (b) - death rate (d) rate of natural
    increase (r)

6
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7
Three Key Features of Populations
Density measurement of population per unit area
or unit volume Pop. Density of individuals
unit of space
8
How Do You Affect Density?
  • Immigration movement of individuals into a
    population
  • Emigration movement of individuals out of a
    population
  • Density-dependent factors Biotic and abiotic
    factors in the environment that have an
    increasing effect as population size increases
    (disease, competition, parasites)
  • Density-independent factors Abiotic factors in
    the environment that affect populations
    regardless of their density (temperature,
    weather)

9
How Do Populations Grow?
  • Idealized models describe two kinds of population
    growth
  • Exponential Growth
  • 2. Logistic Growth

10
Carrying Capacity
  • Carrying Capacity (k)
  • The maximum population size that can be supported
    by the available resources
  • There can only be as many organisms as the
    environmental resources can support

11
Exponential Growth Curve
Figure 35.3A
12
Logistic Growth Curve
13
Factors Limiting Growth Rate
  • Declining birth rate or increasing death rate are
    caused by several factors including
  • Limited food supply
  • The buildup of toxic wastes
  • Increased disease
  • Predation

14
Booms and Busts
15
Reproductive Strategies
  • R Strategists
  • Short life span
  • Small body size
  • Reproduce quickly
  • Have many young
  • Little parental care
  • Ex cockroaches, weeds, bacteria

16
Reproductive Strategies
  • K Strategists
  • Long life span
  • Large body size
  • Reproduce slowly
  • Have few young
  • Provides parental care
  • Ex humans, elephants

17
Age Distribution
  • Distribution of males and females in each age
    group of a population
  • Used to predict future population growth

18
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19
Human Population Growth
  • J curve growth
  • Grows at a rate of about 80 million yearly
  • r 1.3
  • Why doesnt environmental resistance take effect?
  • Altering their environment
  • Technological advances
  • The cultural revolution
  • The agricultural revolution
  • The industrial-medical revolution

20
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

21
History of the Human Population
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