Gause’s Principle,Resource Partitioning and Character Displacement

Gause’s Principle

Gause’s principle suggests that the two competing species can coexist.

In 1960, Hardin based on Gause’s principle restated that complete competitors affecting each other with equal magnitude cannot coexit and called it as Competitive exclusion principle.

The population growth effected by the competition between two species of Paramecium depicts the more intense negative effecting population survives at the expense of other. P. aurelia and P.caudatum reaches there carrying capacity when culture alone in laboratory but when these two cultures are mixed and grown together P.aurelia survives while P.caudatum is eliminated.

 Figure 17: Graph illustrating growth inhibition in one species of paramecium on co-culturing them in laboratory.

The species can coexist by reducing the competition via ecological segregation or resource partitioning. In this hypothesis it was suggested that when two species share common resources than they may coexist by partitioning their resources such as food, space etc (figure 18). 

Figure 18: The illustration of Competitive exclusion principle. (1) Small yellow birds utilize the resources all over the tree. (2) On invasion of large red colour birds the competition increases and (3) leads to competition exclusion/resource partitioning between two birds species, thus, the large red birds utilize resource abundant middle part of the tree while small yellow birds consume rest of the resources.

In field some lizards and many insects like ants depicts the coexistence of species through Resource partitioning or ecological segregation.

Character Displacement: Different species develop traits under the influence of competition and can coexist. The best and classical example is set by Finches of Galapagos Island where the Darwin observed that the size and shape of the bird’s beak vary according the vegetation in the Galapagos Island.

Figure 19: Darwin’s Finches