[Explained] Population Growth Curve

 Population Growth Curve Types

Populations exhibit specific pattern of increase. When the number of organisms in a population are plotted against the time, a population growth curve is obtained. Depending
upon the environmental resistance, they are of two types :

(i) J-shaped, and (ii) S-shaped (sigmoid).

In theory, given ideal conditions, a population will double in size during a constant period of time. This is known as exponential growth. The rate of increase in numbers of a population undergoing exponential growth is proportional to the size of the population and when plotted on a graph numbers against time-such a population gives an exponential or J-shaped growth curve . Such optimum
growth rarely occurs, it can be seen occasionally in bacterial populations with carefully managed
environment. In such situations, factors of environmental resistance do not exert any influence.

J Shaped Curve or Exponential population growth curve

Initially, the growth is slow but afterwards the population grows at a rapid rate, that proceeds till enough food is available. However, in nature with limited resources such a situation never arises and various factors of environmental resistance do not allow population growth to soar towards infinity.

S-shaped (sigmoid) growth curve is obtained when the population first increases slowly then more rapidly and finally it slows down gradually due to environmental resistance until an equilibrium level is reached. It signifies the maximum size of population that an environment can carry
or sustain.

Sigmoid population growth curve

Also see, Types of Population Pyramids [also known as Age Pyramids] 
And Also see,  Learn about Carrying Capacity and Environmental Stochasticity
The above mentioned topic are related to the given topic and you might find them useful for you r study. 

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