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Additional notes… Populations & Growth, Limiting Factors

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Presentation on theme: "Additional notes… Populations & Growth, Limiting Factors"— Presentation transcript:

1 Additional notes… Populations & Growth, Limiting Factors

2 Exponential Growth Occurs when individuals in a population reproduce at a constant rate Causes: Ideal conditions with unlimited resources

3 Logistic Growth Populations growth slows or stops following a period of exponential growth Causes: Birth rate decrease, Death rate increases Birth rate and death rate are equal Rate of immigration decreases Rate of emigration increases

4 Limiting Factors Factor that causes population growth to decrease
Competition Predation Parasitism and disease Drought and climate extremes Human disturbances

5 Factors Density Dependent Factors: Limiting factor that depends on population size Density Independent Factors: not dependent on population size

6 Types of Density-dependent Factors
Competition Overcrowding causes organisms to compete for food, water, space and sunlight Predation Predator-prey relationship Parasitism and Disease Parasites take nutrients from host, weakening host, spreading disease or death

7 Density-Independent Factors
Affects all populations in similar ways, regardless of population size Unusual weather Natural disasters Seasonal cycles Human activities

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