Limits to population growth
Carrying capacity: the maximum population size of a species that an ecosystem can support in a stable way.
Although individuals may have the potential to reproduce, environmental conditions limit how many survive and reproduce. These limits include both abiotic factors and biotic interactions.
As population size increases, limiting factors eventually prevent continued growth. Most populations therefore remain at or below the carrying capacity of their ecosystem.
The population size that can be supported depends on the prevailing conditions. Changes in abiotic factors, competition or predation can therefore change the population size that the ecosystem is able to support.
Reaching carrying capacity
- At low population size, resources and other environmental conditions may allow the population to increase.
- As numbers rise, limiting factors have a greater effect on survival and reproduction.
- Population growth slows as the carrying capacity is approached.
- At carrying capacity, environmental factors prevent continued population growth.
Humans may be an exception to the usual pattern because many natural limitations on population growth have been overcome.