1. Populations: Limiting Factors

2. Limits to Growth
In nature, there is rarely an unlimited amount of resources available to living things
There are many factors that limit growth so that it is not exponential, and instead reaches a carrying capacity
What are some things you can think of that would cause a population to level off like it does in logistic growth?

3. Limits to Growth
There are two categories for the factors that limit the growth of a population:
Density-Dependent Limiting Factor
Density-Independent Limiting Factor
Review: A population’s density is the number of individuals of a population per unit area

4. Limiting Factors
Density-dependent Limiting Factor: any factor in the environment that depends on the number of members in a population
Often biotic (living) factors, such as:
Competition
Predation
Parasitism
Disease

5. Example of a Density-Dependent Limiting Factor
As the density of the beetle population increased, the number of beetles alive decreased

6. Limiting Factors
Density-independent Limiting Factor: any factor in the environment that does not depend on the number of members in a population
Usually abiotic (not living) factors that are extreme and unusual:
Natural Disasters
Unusual Weather
Human Activities