1. 7.3 Factors That Limit Population Size
Factors that prevent unlimited population growth are known as limiting factors.
Environmental resistance- all limiting factors that act on a population collectively
Extrinsic limiting factors are those that come from outside the population.
Predators
Loss of food source
Lack of sunlight
Accidents of nature

2. 7.3 Factors That Limit Population Size
Intrinsic limiting factors- factors that originate within the population and exercise control over it.
Ex- Behavioral changes amongst the population cause lower birthrates and higher death rates.
Density-dependent limiting factors are those that become more effective as the density of the population increases.
Density-independent limiting factors are population-controlling influences that are not related to the density of the population.

3. 7.4 Categories of Limiting Factors
For most populations, limiting factors can be placed into four main categories:
Raw material availability
Shelter, minerals, water
Energy availability
Food, sunlight
Accumulation of waste products
Generally only an issue with bacteria
Interactions among organisms
Predation, grazing

4. 7.5 Carrying Capacity
Carrying capacity is the maximum sustainable population for an area.
It is not an inflexible number; it can be influenced by environmental differences such as:
Successional changes
Climate variations
Disease epidemics
Forest fires, floods, or natural disasters
Nutrient levels in aquatic ecosystems

5. 7.5 Carrying Capacity