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In ecology, carrying capacity is the measure of an environment, or habitat, to indefinitely sustain the population of a particular species in a steady-state population density.
An alternative definition for carrying capacity is: the maximum population of a particular species a particular region can support without hindering future generations' ability to maintain the same population. The carrying capacity of an environment will vary for different species in different habitats, and can change over time due to a species impact on its environment, as well as other environmental factors.
Species typically adopt one of two strategies:
- Strategy r-selected : the species has a high reproduction rate, but is very sensitive to environmental factors, in particular predation. Therefore, the populations do exceed the carrying capacity. This strategy is typical of insects.
- Strategy K-selected : the species has a low reproduction rate and usually a long life span. They are submitted to low predation rate and population may grow over the carrying capacity. Environmental stress usually lead to hormonal disrupting to prevent ovulation, or to abortions. This strategy is typical of mammals.
Humans have demonstrated an ability to increase the short term carrying capacity of their environment through use of Earth's available resources, most notably the wide scale use of ancient deposits of hydrocarbons, also known as fossil fuels. Exploitation of these resources has allowed massive short term inputs of energy into human population growth, but at the potential cost of reducing long term carrying capacity through environmental degradation and depletion of non-renewable resources.
When a population exceeds the long term carrying capacity of its environment, also known as overshoot, then famine and disease tend to reduce the size of that population.
See also Ecological yield, Sexual selection, Overpopulation.
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