xxTerwin: Population (Dispersal and Growth Rate)
Terms
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- Dispersal
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Populations tend to spread from one location to another.
May be passive or active.
Sometimes happens in response to limited resources. - Passive dispersal
- Wind, water current, etc.
- Active dispersal
- Under control of organism: running, walking, swimming, flying.
- Dispersal Specifics
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May involve dispersal of emryos (seeds, spores, eggs), larval or juvenile life stages.
Effective ways to populate new regions or acquire resources.
Examples: dandelions; apple seeds; barnacle larvae. - Physical Dispersal barrier
- Mountains, valleys, large bodies of water.
- Habitat specificity and behavior dispersal barrier
- Forest versus grassland inhabitants.
- Climatic variation dispersal barrier
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Arctic & Antarctica are similar but divided by tropical & temperate climate regions.
Different fauna at different poles. - Human dispersal
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Few barriers limit human dispersal.
Space & water. - Earth’s Carrying Capacity
- Based only on food = 7-8 billion people.
- Human Population Growth
- Agriculture & Inustrial Rev have fueled rapid pop expansion.
- Global resource distribution
- Food resources are not equally distributed across globe.
- Malnourished
- Wrong food.
- Undernourished
- Not enough food.
- Ecological footprint
- US residents have large footprint, but not big enough ecological capacity (resource deficit).
- Mexico’s Population
- Mexico has big growth rate due to much youth.