Population Ecology

1
Population Ecology

• The Study of Populations and the Factors that
  Affect Them

2
Characteristics of Populations

• All population have the following
• Geographic distribution (range)
• Population Density - the number of
• individuals in a certain area
• Rate of Growth

3
Factors Affecting Population Growth
population
1) of Births
emmigration
immigration
2) of Deaths
3) Immigration and Emmigration
4
Types of Growth Rates

• Exponential growth - occurs when the reproductive
  rate of a population is constant and NOT limited
  by food, disease, or other factors

5
Types of Growth Rates

• Logistic growth - occurs when the reproductive
  rate of a population levels off or slows down

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Carrying capacity
7
Carrying Capacity

• Maximum population that an environment can
  sustain
• Carrying capacity is limited by several factors
• 1) Density dependent - have a stronger impact on
  dense populations (disease, food availability,
  predation, competition)
• 2) Density independent - impact is the same
  regardless of population density (climate change,
  natural disasters, human intervention)

8
What is biodiversity?

• The variety of life in an area (variety of
  species as well as variety of genetic information
  a species contains)

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Why is biodiversity important?

• Human purposes (ex. Medicine, food, fuel,
  industrial chemicals)
• Makes ecosystems more productive (they produce
  more total biomass)
• Stabilizes ecosystems by creating more niches
  (better resistance to disease and climate change)

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Threats to biodiversity

• Habitat destruction/fragmentation
• Introduction of invasive species
• Habitat degradation (pollution)

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Habitat Fragmentation

• When a habitat is divided into smaller pieces by
  human activity
• Fragments provide fewer resources than whole
  intact habitats

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Change in Species Due to Fragmentation
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Invasive Species

• A species that is not native to its habitat (may
  come from another continent/country/or region of
  the same country)
• May damage its new environment and disrupt the
  natural food web
• Can be costly to control the damage they cause
  (billions of dollars!)

14
Biological magnification

• The accumulation of toxic chemicals going up the
  food chain (concentration of toxins are
  magnified)
• Higher level consumers are most at risk

Red dots toxic chemical
15
Global Pollution Problems

• Climate change (global warming)
• Destruction of the ozone layer
• Acid Precipitation
• Biological magnification of toxic chemicals (on
  previous slide)

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Climate change

• CO2 traps prevents heat from escaping back into
  space
• More fossil fuel burning more CO2 in atmosphere
• Deforestation leads to less trees more CO2 left
  in the atmosphere
• More CO2 more heat trapped WARMER EARTH!

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Greenhouse effect (natural process)
CO2 traps heat