1. A lumped population

In this model, the population is represented by a single compartment, representing the total number of animals in the population or the population density (number per unit area). Reproduction is assumed to be density dependent (the reproductive rate per individual, r, declines as population size increases), whereas mortality is not (the mortality rate per individual, m, is independent of population size).

When the model is run, it shows the expected logistic form of population growth. When there are 80 individuals in the population, the birth rate balances the death rate.