1. Competitive Exclusion Principle Sometimes referred to as Gause's Law of competitive exclusion or just Gause's Law, States that two species that compete for the exact same resources cannot stably coexist One of the two competitors will always have a slight advantage

2. Paradox of the Plankton The best known example is the paradox of the plankton (or short plankton paradox): All plankton species live on a very limited number of resources, primarily solar energy and minerals that are dissolved in the water

3. Paradox of the Plankton Only a small number of plankton species should be able to coexist on these resources Nevertheless, large numbers of plankton species coexist within small regions of open sea