Competitive Exclusion Principle
When two species occupy very similar ecological niches, they depend on the same resources and experience the same pressures. This overlap creates direct competition. According to the competitive exclusion principle, two species cannot indefinitely share an identical niche because one will always have even a slight advantage.
Two species competing for the exact same limited resource cannot stably coexist.
Over time the better competitor will outcompete the other, forcing the weaker species to either shift its niche, move to a different habitat, or decline.
This leads either to the extinction of the weaker competitor or to an evolutionary or behavioral shift toward a different ecological niche.
Therefore, if two competing species coexist in a stable environment, they do so as a result of differentiation of their niche (i.e. they may consume different foods, or use different areas of the environment).
Species survive best when they occupy roles that are similar enough to suit their adaptations yet different enough to avoid being pushed out by stronger competitors.
Solution to Competitive Exclusion: Niche Partitioning
•Also known as niche segregation, niche separation and niche differentiation.
•This is where the niche is divided, so all competing species use the environment differently in such a way that helps them to coexist and therefore survive.
•Each species uses the environment slightly differently, which reduces overlap in their ecological niches.
•This separation can occur through differences in space, time, diet or behaviour.
•By limiting direct competition, niche partitioning allows multiple species to coexist within the same ecosystem.
Niche partitioning: This is where the niche is divided, so all competing species use the environment differently in such a way that helps them to coexist and therefore survive.
Types of Niche Partitioning
•Spatial partitioning
Species use different areas of the habitat. For example, one bird species may forage high in the canopy while another searches on the forest floor.
•Temporal partitioning
Species use the same resource at different times. For instance, one species may feed during the day while another feeds at night.
•Resource partitioning
Species specialise on different types or sizes of the resource. An example is several lizard species eating insects but choosing different kinds or sizes to avoid overlap.
•Morphological partitioning
Species evolve different physical traits that allow them to exploit different resources. Classic examples include finches with differently shaped beaks that suit different seeds.