Graph 1 shows parallel increase in both population which occurs in mutualism as both the organisms are benefited by the association. Graph 2 shows increase in one population (the black line) and no change in other population as it happens in commensalism. One organisms is benefited by commensalism while the other one is neither harmed nor benefited. Graph 3 exhibits parasitism as increase in one population (the black line; the parasite population) results in reduction in population size of other organism (the red line represents host population). Graph 4 exhibits prey predator association wherein increase in population size of predator causes reduction in prey population. However, reduced prey population size causes starvation induced reduction in the population size of predator.
