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