Changing Population Notes
Populations increase by:
1) Reproduction (birth)
2) Immigration (organisms entering the area)
Populations decrease by:
1) Death
2) Emigration (organisms leaving the area)
Without limiting factors
 reproduction > death
Limiting Factors – Anything that causes populations to decrease
(death rate exceeds birth rate or emigration exceeds immigration).
Carrying Capacity- the maximum population a species can maintain in a certain area without damaging the ecosystem.
(See Example graphs)

Limiting Factors:
1) Space – This is the most essential limiting factor. Animals that are territorial (hunting or breeding area) are often limited by space.
Loss of habitat is a loss of space for many organisms. Ex.
2) Food (nutrients) and Water (Rainfall for plants) – Lack of these will cause starvation or emigration. Organisms relying on only one typed of food are most severely affected. Ex.
3) Climate and weather – Temperature changes will affect plant and animal survival. Floods and severe storms also cause deaths.
Ex.
4) Cover - Without places to hide organisms are more susceptible to predators and harsh weather. Ex.
5) Increase predation – An increase in the number of predators to an area. Ex.
6) Disease – Diseases will spread though populations with a high population density. Ex.
7) Light – Plants that cannot tolerate shade will die or fail to reproduce. Ex.
8) Human Presence - The close proximity of humans may cause certain organisms to emigrate. Ex.

Competition among organisms for one of the above factors can cause a decline in populations.

Competition has increased due to exotic species
Exotic Species -