Exponential growth is any change in numbers with time that occurs at a constant per capita rate. 1 might be a natural example of how bacteria multiply over time. This formula simply means that the slope of the line for N as a function of t is given by r N . So, the rate of change in numbers is proportional to the numbers present.
Constant r represents the per capita recruitment rate in each time increment.
It is a net value, being the net surplus of births after subtracting deaths. Because each individual generates new individuals, population size increases by multiples of itself over time. This is the only number that makes the exponential its own derivative. For discrete growth intervals, the constant e r is sometimes referred to as R , the fundamental net recruitment rate', which is a scaling factor.