What is the Competitive Exclusion Principle with examples and explanation
The Competitive Exclusion Principle was first proposed by G.F Gause. According to the principle he stated, those species which compete for the same resources cannot coexist. This principle is also known as Gause’s law. By this law, it is stated that one population will drive off the other one. The one remaining in the system definitely has strong adapting capacity. Let's suppose that, if a forest's maximum population is carnivores, then definitely in that area there will be a shortage of food. This will cause scarcity of food among animals which causes competition among the animals due to competition of best survival. The one who has strong power will definitely defeat the weaker section and by the passage of time, the weaker section will get eliminated.
One more example of competitive exclusion is, how red squirrels replaced the grey squirrels in Britain? Suddenly the number of squirrels decreased in Britain because of the disappearance of hazelnuts, which led to competitive exclusion. Whereas gray squirrels adapted to the situation and replaced the red squirrels eventually.
History:
The competitive exclusion principle was initially given by Georgii Gause, but basically, he never formulated this principle. This principle was already there in Darwin’s theory of natural selection. This principle revolves between a priori and experimental truth.
Prediction:
The competitive exclusion principle is also predicted by mathematical and theoretical models like Lotka-Volterra medals of competition. But because of its weak reasons, competition exclusion is hardly observed in natural ecosystems, and many biological communities appear to violate Gause’s law. One of the best-known examples is the so-called “paradox” of the plankton. All plankton species survive on a very limited number of resources, mainly on solar energy, only a very small number of plankton species should be able to coexist on these resources.
Types of Competition In Competitive Exclusion:
There are mainly two types of competitions in the competitive exclusion principle:
1. Interspecific Competition: In this, competition takes place between organisms of different species.
2. Intraspecific Competition: In this, competition takes place between organisms of the same species.
Sub-Types of Competitions:
1. Interference: Where there is a direct flight between organisms for resources, it is called interference. For example: when animals protect their food from other animals, for best survival.
2. Exploitation: It is a condition when an organism uses all resources, leading to depletion of resources for other animals. Such a condition is known as exploitation. In this condition, there is a direct fight for resources. It is a natural phenomenon and leads to the evolution of organisms.
3. Ecological Niche: The niche is the way of life of a species marked by the set of conditions, resources and interactions it requires. Every species has its own capacity to fit in its ecological community and have a tendency to tolerate various environmental factors to a certain extent. Example: Species of fish is classified on the basis of specific salinity range, pH level and also the type of food they consume.
In case, if two organisms have the same niche, then it is very difficult to survive in the same environment due to the presence of competition between them.
4. Resource Partitioning: In case if one or both the species belong to the same niche, then they undergo evolution to use their resource in different ways or they develop best feeding habits for best survival and by this method competition exclusion can be avoided. As such, the evolution process leads to non-overlapping of resources resulting in different niches. By this process, it becomes easy to exist together.
For example, Anole lizards are found in large numbers in the Island of Puerto Rico. These lizards evolved over time due to the natural selection process and they got further differentiated into 11 more new species that use different kinds of resources and also live in different habitats. This is the example of resource partitioning.
Important Questions
How many types of competitions are present according to the Competitive Exclusion Principle?
Ans: There are broadly two types of competitions known - Interspecific competition and Intraspecific competition.
Which of the following best describes an Ecological Niche?
A cramped, small habitat
A hole in the food chain
An organism's role in its ecosystem
The losing species of competitive exclusion
Ans: An ecological niche basically describes the way an organism survives, feeds itself, and builds its shelter in its environment. It means ecological niche talks about the role the organism plays and how it responds to its environment. Hence, the correct option is (c).
Key Features
Competitive Exclusion Principle states that species competing for the same resources or food do not exist together and one turns up driving off the another one.
The principle is also known as the ‘Gause’s law’ as it was first proposed by G.F Gause.
There are broadly two types of competitions - Interspecific competition and Intraspecific competition.
FAQs on Competitive Exclusion Principle in Ecology
1. What is the Competitive Exclusion Principle?
The Competitive Exclusion Principle states that two species competing for the exact same limiting resource cannot stably coexist in the same habitat. When two species occupy the same ecological niche, one species will outcompete and eliminate the other over time.
- Also called Gause’s Law.
- Applies when resources such as food, space, or light are limited.
- Results in either extinction or niche differentiation of one species.
2. Who proposed the Competitive Exclusion Principle?
The Competitive Exclusion Principle was proposed by G. F. Gause in 1934 based on laboratory experiments with protozoa. Gause studied two species of Paramecium grown together under controlled conditions.
- When grown separately, both species survived.
- When grown together with the same food source, one species eliminated the other.
- This demonstrated that complete niche overlap leads to competitive exclusion.
3. What is meant by ecological niche in the Competitive Exclusion Principle?
An ecological niche refers to the functional role and resource use of a species within its ecosystem. It includes how a species obtains food, uses space, and interacts with other organisms.
- Habitat: Where the species lives.
- Trophic role: What it eats and what eats it.
- Environmental conditions: Temperature, light, moisture requirements.
4. Can two species coexist in the same habitat under the Competitive Exclusion Principle?
Two species can coexist in the same habitat only if they do not occupy the exact same ecological niche. Coexistence is possible when species reduce competition through resource partitioning.
- They may use different food sources.
- They may feed at different times.
- They may occupy different microhabitats.
5. What is an example of the Competitive Exclusion Principle?
A classic example of the Competitive Exclusion Principle is Gause’s experiment with Paramecium aurelia and Paramecium caudatum. When both species were grown together in the same culture medium:
- They competed for the same bacterial food source.
- P. aurelia reproduced faster.
- P. caudatum was eventually eliminated.
6. How does resource partitioning prevent competitive exclusion?
Resource partitioning prevents competitive exclusion by allowing species to use different portions of a shared resource, reducing direct competition. This leads to niche differentiation.
- Species may feed at different heights in a tree.
- They may consume different sizes of prey.
- They may be active at different times (day vs night).
7. What is the difference between competitive exclusion and resource partitioning?
The main difference is that competitive exclusion leads to the elimination of one species, while resource partitioning allows coexistence by reducing competition.
- Competitive exclusion: Complete niche overlap → one species outcompetes the other.
- Resource partitioning: Partial niche overlap → species divide resources and coexist.
8. Why is the Competitive Exclusion Principle important in ecology?
The Competitive Exclusion Principle is important because it explains patterns of species distribution and biodiversity in ecosystems. It helps ecologists understand how species interactions shape communities.
- Explains why closely related species rarely occupy identical niches.
- Predicts outcomes of invasive species competition.
- Helps interpret species diversity and ecosystem stability.
9. Does the Competitive Exclusion Principle apply to all organisms?
The Competitive Exclusion Principle applies to all organisms that compete for the same limiting resources, including plants, animals, and microorganisms. However, real ecosystems are complex and often allow coexistence through niche differentiation.
- Applies in plants competing for light and nutrients.
- Applies in animals competing for food or territory.
- Most evident when resources are strongly limiting.
10. What happens if two species have identical resource requirements?
If two species have identical resource requirements and compete in a stable environment, one species will eventually eliminate the other due to competitive exclusion. This occurs because even small differences in efficiency lead to dominance.
- The superior competitor uses resources more efficiently.
- The weaker competitor experiences reduced growth and reproduction.
- Over time, the weaker species declines to local extinction.
