In a population of a habitat …

    
Two types of population growth patterns may occur depending on specific environmental conditions:

• An exponential growth pattern (J curve) occurs in an ideal, unlimited environment
• A logistic growth pattern (S curve) occurs when environmental pressures slow the rate of growth

Exponential Growth

• Exponential population growth will occur in an ideal environment where resources are unlimited
• In such an environment there will be no competition to place limits on a geometric rate of growth
• Initially population growth will be slow as there is a shortage of reproducing individuals that may be widely dispersed
• As population numbers increase the rate of growth similarly increases, resulting in an exponential (J-shaped) curve
• This maximal growth rate for a given population is known as its biotic potential
• Exponential growth can be seen in populations that are very small or in regions that are newly colonised by a species

Logistic Growth

• Logistic population growth will occur when population numbers begin to approach a finite carrying capacity
• The carrying capacity is the maximum number of a species that can be sustainably supported by the environment
• As a population approaches the carrying capacity, environmental resistance occurs, slowing the rate of growth
• This results in a sigmoidal (S-shaped) growth curve that plateaus at the carrying capacity (denoted by κ)
• Logistic growth will eventually be seen in any stable population occupying a fixed geographic space