Now that we have a conceptual model for population growth, we can tear it apart.  Competition for limited resources implies that populations will not grow indefinitely — taking that as a starting point, we can derive a conceptual model for the more realistic setting of populations growing under resource constraints.

1. • More individuals competing for finite resources results in lower per capita resource
   • Competition can be characterized in terms of the interaction (interference v. exploitation) or the outcome (scramble v. contest)
   • Competition can limit birth rate, death rate, or both — when they are equal, the population is constant at the carrying capacity