Lionfish Invasion: Density-Dependent Population Dynamics

Exploring changes in the population growth rate

The previous examples showed that the lionfish population’s growth rate was not constant. Instead, the rate changed over time as the population grew bigger. Let’s examine how the overall growth rate $\frac{dN}{dt}$ changes depending on the population size $N$.

Click on each point highlighted on the graphs to compare $N$ and $\frac{dN}{dt}$ in the table to the right. Because $\frac{dN}{dt}$ is the change in the population over the change in time, it is equal to the slope of the line at that point.

Answer the following questions using the graphs above.