Question

Comment on the growth curve given below.

Answer 1

Definition

Logistic population growth curve is a graph that represents the Verhulst-Pearl Logistic Growth. This graph is formed when population density ($N$) is plotted against time $t$.

Components

The curve is sigmoid or $S$-shaped in nature as the population has the following growth pattern:-

● Lag phase: Represented by the first part of the curve, this is the time when the population is getting adjusted to the environment.

● Log phase: The second part of the curve shows exponential increase in the population as the resources are available. There are three phases between lag phase and stationary phase as follows:

○ Positive acceleration phase: Limited growth in population as the resources are available

○ Exponential growth phase: Suddenly and very rapid growth of population

○ Negative acceleration phase: Decrease in the growth rate of the population due to competition and environmental resistance

● Stationary phase: As population density increases, competition among species increases, resources become a limiting factor resulting in the slowdown of growth. The population reaches the carrying capacity ($K$) of the environment.

Equation

The following equation represents the $dN/dt=rN${$(K-N)/K$}

Where $N=$ Population density at time $t$

$t=$ Time

$r=$ Intrinsic rate of natural increase

$K=$ Carrying capacity (maximum possible number of organisms in an environment, beyond which no further growth can take place)