1. Lesson Overview
5.2 Limits to Growth

2. Limiting Factors
A limiting factor is a factor that controls the growth of a population.
May be density dependent or independent.

3. Density-Dependent Limiting Factors
Density-dependent limiting factors include competition, predation,herbivory, parasitism, disease, and stress from overcrowding.
small, scattered populations are not affected as much

4. Stress From Overcrowding
overcrowded STRESS
stress weakens the body’s immune system
In some species, stress from overcrowding can cause females to neglect, kill, or even eat their own offspring.
Stress from overcrowding can lower birthrates, raise death rates, or both, and can also increase rates of emigration.

5. Density-Independent Limiting Factors
Density-independent limiting factors affect all populations, regardless of population size and density.
Ex: weather- hurricanes, droughts, or floods, and natural disasters such as wildfires

6. True Density Independence?
Isle Royale- the moose population grew exponentially for a time after the wolf population crashed.
bitterly cold winter- moose decreased
island population-no emigration or immigration
effects of bad weather on the large, dense population were greater than they would have been on a small population.