1. Population Characteristics
Populations are groups of the same species in the same area
Characteristics of populations include density, distribution, and growth rate
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Population Dynamics

2. Population Characteristics
Population density
The number of organisms per unit area is the population density.
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Population Dynamics

3. Population Characteristics
Spatial distribution
Dispersion is the spacing pattern of a population.
Can be uniform, clumped groups, or random
Pattern primarily driven by resources such as food
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Population Dynamics

4. Population Characteristics
Population ranges
A species’ range is its distribution across the environment.
A species might not be able to expand its population range because it cannot survive the abiotic conditions found in the expanded region.
Dispersion
Uniform
Clumped
Random
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Population Dynamics

5. Add link to concepts in motion animation from page 93 here.
Visualizing Population Characteristics
Animation
FPO
Add link to concepts in motion animation from page 93 here.
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Population Dynamics

6. Population-Limiting Factors
Limiting factors are biotic or abiotic forces that keep populations from increasing indefinitely.
Limiting factors are either density-independent or density-dependent.
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Population Dynamics

7. Population-Limiting Factors
Density-independent factors
Any factor in the environment that does not depend on the number of members in a population per unit area is a density-independent factor.
Usually abiotic, and include:
Weather events
Fire
Human alterations of the landscape
Air, land, and water pollution
Population Dynamics
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8. Population-Limiting Factors
Density-dependent factors
Any factor in the environment that depends on the number of members in a population per unit area is a density-dependent factor.
Often biotic, and include:
Predation
Disease
Competition
Parasites
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Population Dynamics

9. Population-Limiting Factors
Population growth rate
The population growth rate (PGR) explains how fast a given population grows.
Natality: birthrate of a population in a given year
Emigration: number of individuals moving away from a population
Immigration: number of individuals moving into a population
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Population Dynamics

10. Population-Limiting Factors
Population growth rate
Exponential growth model:
Occurs when growth rate is proportional to population size
All populations grow exponentially until they encounter a limiting factor.
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Population Dynamics

11. Population-Limiting Factors
Population growth rate
Logistic growth model:
Occurs when a population’s growth slows or stops following exponential growth
number of births < number of deaths
when emigration > immigration.
Population Dynamics
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12. Population-Limiting Factors
Population growth rate
Carrying capacity
Carrying capacity is the maximum number of individuals in a species that an environment can support
Population Dynamics
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13. Add link to concepts in motion animation from page 97 here.
Characteristics of Population Growth
Animation
FPO
Add link to concepts in motion animation from page 97 here.
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Population Dynamics

14. Population-Limiting Factors
Reproductive patterns
Species vary in the number of births per reproduction cycle, age that reproduction begins, and in the life span.
Plants and animals are placed into groups based on their reproductive factors.
r-strategy
k-strategy
Rate strategy
Carrying-capacity strategy
Adapted for fluctuating environment
Adapted to stable environment
Generally small
Generally large
Short life span
Long life span
Many offspring
Few offspring
Expend little energy to raise young
Invest more energy into nurturing young
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Population Dynamics

15. Review Essential Questions Vocabulary
What are the characteristics of populations and how they are distributed?
What are the differences between density-independent and density-dependent limiting factors?
What are the similarities between the different models used to quantify the growth of a population?
How does carrying capacity affect reproductive rates?
Vocabulary
population density
dispersion
density-independent factor
density-dependent factor
population growth rate
emigration
immigration
carrying capacity
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Population Dynamics