Competitive Exclusion Principle

Competitive Exclusion Principle, also known as Gause’s law, states that two species that compete for the same resource cannot coexist; over time, one species may outcompete the other, leading to the elimination of the inferior species. In ecology, there are two types of competition: Intraspecies and Interspecies competition. Competition is a vital stage in the sequence of ecological succession. It can benefit the broader ecosystem by promoting biodiversity through niche partitioning.

This article discusses the significance of the competitive exclusion principle and the types of competition that exist in nature, competition-minimizing strategies that species use to efficiently enhance the biodiversity of their ecosystem.

Competitive Exclusion Principle

The competitive exclusion principle was proposed in 1934 by a Russian ecologist Georgy Gause, hence the name ‘Gause’s Law’. According to this concept in ecology, two species with identical or similar niches, competing for the same resources, cannot coexist.

One of the species will outgrow the other and the species with the inferior niche will go extinct over time. However, two species whose niches overlap may evolve to have more distinct niches, resulting in resource partitioning. The competitive exclusion principle can also lead to the extinction of the weaker competitor or to an evolutionary or behavioral shift toward a different ecological niche.

Example of Competitive Exclusion Principle

If a lake is filled with fish and there are two species of birds with similar niches (diets, feeding habits, etc.) that start competing for the fish. The species that can access the fish more efficiently might consume most of the fish and over time, this could lead to the exclusion or elimination of the presence of the less dominant bird species.

Another instance of competitive exclusion is the replacement of grey squirrels by red squirrels in Britain. Diseases, competitive exclusion, and the absence of hazelnuts all contributed to the decline in the population of red squirrels. Red squirrels were eventually replaced by grey squirrels, which were able to adapt to their surroundings with ease.

Types of Competitions in Competitive Exclusion

To fully understand the competitive exclusion principle it is important to understand the types of competitions that exist in nature. There are two kinds of competitions- interspecific competition and intraspecific competition, let’s discuss them in detail.

Interspecific Competition

This type of competition occurs between organisms belonging to different species as they compete for the same resources in an ecosystem. Types of interspecific competition include:

• Exploitative Competition: Also known as resource competition, organisms of different species compete for the same limited resources, such as food, water, or space. The superior and more competent species may consume these resources more efficiently and outcompete others, leading to reduced resources for competing species.
• Interference Competition: In this type of competition, species directly interfere with each other’s access to resources through aggressive behaviors, and other interactions that hinder resource availability.
• Apparent Competition: While this is not a direct competition for resources, here, two species may indirectly influence each other’s populations via interactions such as similar predators, pathogens, or other external factors, leading to competitive interactions without directly competing for the same resources.

Intraspecific Competition

This type of competition occurs between organisms belonging to the same species as they compete for resources within a population or ecosystem. Types of intraspecific competition include:

• Scramble Competition: In this type of competition, organisms within the same species fight for resources by exploiting them simultaneously, which leads to a decrease in resource availability for all organisms in the ecosystem. In scramble competition, due to limited resource access, decreased growth, reproduction, or survivability are observed within the population.
• Contest Competition: This type of competition involves direct competitions or contests between organisms within the same species for resources, habitat, mates, etc. thus leading to hierarchy and, dominance within populations.

Strategies Helpful in Minimizing Competition

Various strategies in nature minimize competition within species, these include:

Ecological Niche

Ecological niche helps facilitate coexistence and minimizes competition among species by specifying the definite roles, resources, and interactions that differentiate each species present in an ecosystem. It includes the range of conditions needed for the species to survive, and its role in the ecosystem. An ecological niche includes:

• The physical space an organism occupies
• The organism’s functional role in the community
• How the organism responds to the distribution of food and competitors
• How the organism alters those same factors.

The niche of an organism is based on its adaptations or traits for survival. For example, the flightless dung beetle (Circellium bacchus) occupies a unique ecological niche. They feed on animal droppings and store them as dung balls in burrows. The concept of an ecological niche is important in ecology because it helps us understand the geographical distributions of species.

Resource Partitioning

It is a strategy that minimizes competition amongst species by division of resources; it lessens the direct competition for the same limited resources within a shared habitat. This can involve using resources at different times, in different ways, or in different areas. This adaptive strategy encourages biodiversity whilst lessening competitive pressures and facilitating the coexistence of numerous species within an ecosystem. Resource partitioning is an evolutionary adaptation that helps various species coexist in an ecological community. It can reduce competition between species and increase species diversity in a habitat.

Conclusion – Competitive Exclusion Principle

Competitive exclusion principle explains the dominance of one species over another. As different species compete for resources, organisms with advantageous traits hold a competitive advantage i.e., increased survival, reproduction, resource utilization, etc., and are more likely to succeed in their environment. Over time, these beneficial traits become more prevalent within populations through natural selection, leading to evolutionary changes, and the development of diverse ecosystems.

FAQs on Competitive Exclusion Principle

Who Formulated the Principle of Competitive Exclusion?

G.F. Gause proposed the competitive exclusion principle in 1934. Gause conducted a laboratory experiment using two species of Paramecium and based his theory on the result of the experiment.

What is an Example of Competitive Exclusion?

In lakes and rivers, various species of fish may have similar feeding preferences and therefore compete for limited food resources. Over time, the more efficient predator species of fish might exclude the other species from that specific ecosystem.

What is the Principle of Competitive Exclusion in Bacteria?

Competitive exclusion for bacteria refers to the situation where numerous species of bacteria compete for available nutrients and mucosal adhesion sites. To gain an edge, the superior bacteria species may modify their environment to make it less suitable for other bacteria that are present in their ecological niche.

What is Meant by Competitive Exclusion?

Competitive release is a concept according to which between the two competing species one of them disappears, allowing the remaining species to use the available resource more efficiently.

What is the Difference Between Resource Partitioning and Ecological Niche?

Ecological niche defines a species’ specific role and interactions within its habitat, while resource partitioning is an adaptive strategy used by multiple species to minimize competition by dividing the available resources thus enabling coexistence.