Transcript Population Dynamics

Population Dynamics
E.Q. What are the factors that
affect a population in an
ecosystem?
Population characteristics
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•
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Population density
Population range
Population growth rate
Population limiting factors
– Density-independent
– Density-dependent
• Spatial distribution or dispersion
– Uniform
– Clumped
– Random
• 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?
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
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
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
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
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.
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
Population growth rate
• Carrying capacity – the maximum number of a
population that an environment can support
long-term
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
Determining populations
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B
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D
Determining populations
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B
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D
Determining populations
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B
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D
How do we determine population
of species in ABCD?
Population in area A = 38
Total population of ABCD = 152
Determining populations
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B
C
D
Determining populations
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B
C
D
Determining populations
A
B
C
D
Determining populations
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B
C
D
List the possible explanations for the change in population dispersion.
Determining populations
1. Disease
A
B 2.
Parasites
3. New
predators
4. Competition
5. Climate
change
6. Carrying
capacity
C
D 7.
Emigration
List the possible explanations for the change in population dispersion.
Quiz
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6.
Carrying capacity
Emigration
Dispersion
Population range
Population density
Immigration
a. # of individuals in a
population
b. Individuals entering a
population from outside
c. Geographical area a
population inhabits
d. Pattern of distribution
e. Population limit in an
area
f. Individuals leaving a
population