Population Dynamics

1
Population Dynamics

• E.Q. What are the factors that affect a
  population in an ecosystem?

2

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Population characteristics

• Population density
• Population range
• Population growth rate
• Population limiting factors
• Density-independent
• Density-dependent
• Spatial distribution or dispersion
• Uniform
• Clumped
• Random

4

• Map shows Current (dark green) and Historic
  Range (light green) of Grizzly Bears in North
  America
• What is your best hypothesis about the reasons
  for the change in the population range of grizzly
  bears in North America?
• What geographical feature seems to most strongly
  determine the population range of the grizzly
  bear?

5
Population characteristics

• Population density the number of an organism
  (species) that lives in a unit area (acre, square
  mile, 100 square miles, etc.)
• Spatial distribution or dispersion the pattern
  of spacing of a population in an area

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Population characteristics - dispersion patterns

• (a) Clumped dispersion - certain animal species
  are grouped in herds plant species sometimes
  grow around specific features like ponds or lakes
• (b) Uniform dispersion certain animal species
  are territorial some plant species produce a
  same species toxin that limits reproduction or
  settlement within a given range
• (c) Random dispersion members of a population
  are distributed in a random fashion that is
  unrelated to the presence of others

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Population characteristics

• Population range the geographical area in which
  an organism or population can live
• Limited by abiotic factors such as temperature,
  humidity, rainfall, sunlight
• Limited by biotic factors such as competitors,
  predators, parasites
• Primary limiting biotic factor - food

8
Map A shows Grizzly Bears in North America and
Map B shows Current Range of Polar Bears in NA.
Based on the maps, what can you tell about the
population range and relationship between the 2
species?
Map A
Map B
9
Population characteristics

• Population limiting factors factors that
  prevent a population from growing indefinitely
• Density independent factors anything that does
  not depend on the number of a population in a
  unit area. Usually abiotic weather, fire,
  pollution
• Density dependent factors anything that does
  depend on the number of a population in a unit
  area. Usually biotic predation, competition,
  disease, parasitism.

10
Population characteristics

• Population growth rate the speed at which a
  given population grows
• Gestation period, natality (birth rate),
  longevity, death rate
• Emigration individuals organisms leaving a
  population
• Immigration individual organisms moving into a
  population

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Population growth rate

• Carrying capacity the maximum number of a
  population that an environment can support
  long-term

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Population characteristics

• Population density ( of species in an area)
• Population range (latitude, altitude, climate,
  etc.)
• Population growth rate (births, deaths,
  longevity, reproduction rate, emigration,
  immigration)
• Population limiting factors
• Density-independent (abiotic factors, weather,
  climate, carrying capacity)
• Density-dependent (disease, competition,
  parasites)
• Spatial distribution or dispersion
• Uniform
• Clumped
• Random

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Determining populations
A
B
C
D
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Determining populations
A
B
C
D
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Determining populations
B
A
C
D
How do we determine population of species in
ABCD? Population in area A 38 Total population
of ABCD 152
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Determining populations
A
B
C
D
17
Determining populations
A
B
C
D
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Determining populations
A
B
C
D
19
Determining populations
A
B
C
D
List the possible explanations for the change in
population dispersion.
20
Determining populations

1. Disease
2. Parasites
3. New predators
4. Competition
5. Climate change
6. Carrying capacity
7. Emigration

A
B
C
D
List the possible explanations for the change in
population dispersion.
21
Quiz

1. Carrying capacity
2. Emigration
3. Dispersion
4. Population range
5. Population density
6. Immigration

1. of individuals in a population
2. Individuals entering a population from outside
3. Geographical area a population inhabits
4. Pattern of distribution
5. Population limit in an area
6. Individuals leaving a population