Transcript Population Dynamics

Population Dynamics
Characteristics of a
population
• Geographical distribution – Describes area
inhabited by population
• Density – The # of individuals / area
• Growth Rate – The change in # within a
population due to births, deaths, immigration, &
emigration
• Age Structure
Exponential Growth
• Occurs when individuals in a population
reproduce at a constant rate
• Under ideal conditions with unlimited
resources, a population will grow
exponentially
Logistic Growth
Occurs when resources become less
available (Slows population growth rate)
Slow population growth rate due to
1. Decrease in birthrate
2. Increase in deathrate
3. Immigration decreases
4. Emigration increases
Carrying Capacity
The largest # of
individuals an
environment can
support
Limits to population growth
Limiting Factor – causes population growth to decrease
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Density Dependent Limiting Factors
Factors which work best with a large dense population
Interspecific competition
Intraspecific competition
Predation
Disease
Parasitism
Density Independent Limiting Factors
Tornado, hurricane, drought, temperature
Human disturbance (Clear-cutting forests or damming rivers)
Competition
Competitive exclusion principle
• No two species can occupy the same niche
in the same habitat at the same time
• Interspecific competition occurs between
two species for similar resources
• Intraspecific competition occurs within a
species for similar resources
Why Competition?
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Limited resources
Food
Water
Space
Shelter
Mates
Sunlight
Predation
Prey have evolved defense mechanisms to
prevent predation
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Poison (Monarch butterflies & Dart frogs)
Mimicry
Camouflage
Shells
Slime
Poison
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Batesian mimicry
• Monarch butterfly
or viceroy
butterfly?
Mertensian mimicry
(Warning coloration)
• Coral snake or King snake?
Camouflage in nature
Industrial
melanism of
the peppered
moth
Shells as
Defense
Slime as Defense
Human Population Growth
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Exponential growth due to:
Agriculture
Industry
Better healthcare / medicine
Reduced death rate
High birth rate
Demography
The scientific study of human populations
• Birthrates
• Deathrates
• Age structure
U.S. Age Distribution
South Africa Age
Distribution
South Africa and U.S.