Two types of population extension models may happen depending on particular environmental circumstances:
An exponential growth pattern (J curve) happens in absolute, unlimited conditions.
A logistic growth pattern (S curve) happens when environmental forces slow the rate of growth.
Exponential growth pattern happens when a population's growth slows or interferes following a phase of exponential growth. It is the greatest number of people that the given conditions can maintain. It is a factor that produces population growth to decline. Some limiting factors influence a population more steadily as the population rises considerably.