Population%20Dynamics

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Population Dynamics
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Population

• Organisms of one species that occupy a particular
  place at a particular time

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Population density

• Number of organisms per unit area

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Population dynamics

• Study of how populations changegrow or shrink
• Why does that matter?
• It could be a sign of a problem in the
  environment or with human activity

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Population growth

• Births Immigration
• Population decline
• Deaths Emigration

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What factors in the environment can influence
birth, death, immigration and emigration?

• Density-independent factors factors that will
  influence a populations numbers regardless of
  the density of the population

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Examples of density-independent factors

• Catastrophes (like flood, fire, earthquake, etc.)
• Pollution/presence of certain pollutants
• Nutrients present in soil and water (such as
  Nitrogen or Phosphorus)
• Oxygen availability
• Extreme weather (very hot summer, very cold
  winter, early freeze, etc.)
• Seasonal weather variations

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• Density-dependent factors factors that influence
  a populations numbers as the population becomes
  more dense (more organisms in a given space)

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Examples of density-dependent factors

• Food supply
• Availability of shelter
• Availability of potential mates
• Disease
• Predation
• Competition for resources
• Parasites

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When few limitations exist

• Populations grow exponentially

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But eventually something limits population size

• So populations exhibit logistic growth

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Limits to growth cause a population to reach its
carrying capacity

• Carrying capacity is the number of a population
  that can be sustained over time