Competition Definition in Biology

Competition is a relationship between organisms in which one is harmed when both are trying to use the same resource related to growth, reproduction, or survivability. Competition stems from the fact that resources are limited. There are simply not enough of some resources for all individuals to have equal access and supply. Competition can occur between organisms of the same species, or between members of different species.

Competition between species can either lead to the extinction of one of the species, or a decline in both of the species. However, this process can often be interrupted by environmental disturbances or evolution, which can change the rules of the game. Competition is often involved when species are limited in their range, often by direct competition from other organisms.

Examples of Competition

Intraspecific Competition

Intraspecific competition is a density-dependent form of competition. “Intra” refers to within a species, as opposed to “inter” which means between. 

The carcass is a resource, something both organisms need to survive. Intraspecific competition is density dependent for one reason. The more dholes you have, the less food each one gets. To the individual dhole, food is everything. With very few predators of their own, the most successful dholes (the ones who survive and reproduce the most) often are simply the ones who eat the most.

Thus, while these dholes may have coordinated to take down this deer, they are now competing to see which one will get to eat first. The one that eats first will get more, and be more likely to survive and reproduce. The other one (or the last one if there are many) will not get as much. This will lower its survivability and the chances it will get to reproduce. Since evolution relies mainly on which organisms reproduce, this form of competition can quickly lead to changes in a population if only a few of the individuals are surviving and reproducing.

Interspecific Competition

Interspecific competition is between individuals which are different species. This could be between any two species, as long as they are competing over a resource. An interesting example of interspecific competition is found in coastal marine environments, like the coral reef .

There are dozens of species. There are several species of fish. Behind them, as a backdrop many people would ignore, is a canvas of dozens of species of coral. Coral, while it may look like some sort of rock or plant, is actually a colony of tiny animals. These tiny animals filter organic material from the water, and use stored bacteria to photosynthesize sunlight for additional energy. Thus, each coral species is competing with not only the other corals, but also with the fish for available nutrients and sunlight.

While corals might not seem like a competitive bunch, they are actually directly competitive with other corals. When an enemy coral is encroaching on their space, they can deploy chemical warfare to counter their rival. Often, coral fights end in one of the corals being killed by the other. While the corals are not predators of each other, the competition still ends in the death of one of the corals. The victorious coral was simply fighting for the resources it needs.

Direct and Indirect Competition

There is also another aspect of competition that can be applied to scenarios of limited resources, and that is the idea of direct vs indirect competition. Direct competition is like both of the scenarios above, and there are many more examples of it. Any time two or more animals fight or have a symbolized confrontation, this is probably some sort of competition for a resource.

However, indirect competition is when the two animals do not interact, but the presence of both animals in the same territory causes the competition. Think of the fish in the example above. If those fish feed on the same resources used by the corals, then the fish are in competition for the limited resources. 

Coral, being more or less anchored to the ocean floor, have little chance of directly attacking the fish. Instead, this would be referred to as an asymmetrical indirect competition. The fish eat as much of the food as they want, and the coral are limited to scraps. The coral have no way of competing. Luckily for most coral reef systems around the world, the ocean has plenty of food for most.

Outcomes of Competition

Competition is not a static process. Once set in motion, it can go a number of different ways. While the models may show that it will eventually drive one species to extinction, in reality a number of things can happen. First, an environmental disturbance, such as a fire or large wave, can upset the ecosystem and destroy the advantage the best competitor had. 

Typically, a pinewood forest is made mostly of pine trees because they are the best competitors in the environment. However, after a forest fire the most populous plants are small, opportunistic plants that grow quickly. The fire causes a change in the environment, which completely changes the dynamics of competition.

Further, most competition is also an evolutionary pressure on both parties. Animals from both sides that compete the best are able to survive and reproduce. Thus, over time the competition tends to resolve itself. More often than not, the competition can devolve as the species adapt to use different resources or change the way it uses a resource. This is known as character displacement. It is most well-documented in finches. 

When two different species of finch live on separate islands, their beaks are the same size because they prefer similar seeds. When they occupy the same island, one of their beaks gets smaller while the other gets larger. This separates the resources they consume and alleviates the competition.


What is competition in biology?

Competition in biology refers to the interaction between organisms or species that rely on the same limited resources, such as food, water, or habitat. This competition can have significant impacts on the survival and reproduction of individuals and populations.

What are the different types of competition in biology?

There are two main types of competition in biology: intraspecific competition, which occurs between individuals of the same species, and interspecific competition, which occurs between individuals of different species. Both types of competition can have important ecological and evolutionary consequences.

What are some examples of competition in biology?

Competition in biology can take many forms, such as competition for food among different species of birds, competition for territory among wolves, or competition for sunlight among plants in a forest canopy. In some cases, competition can be indirect, such as when organisms compete for resources that are affected by other organisms, like pollinators or prey.

How does competition affect populations and ecosystems?

Competition can have important effects on the dynamics of populations and ecosystems. In some cases, competition can lead to resource partitioning and niche differentiation, where different species evolve to use resources in different ways to avoid competition. In other cases, competition can lead to exclusion or extinction of one or more species, which can have cascading effects on the rest of the ecosystem.

How can we study competition in biology?

Competition in biology can be studied using a variety of approaches, such as observational studies of natural populations, experiments in controlled environments, and theoretical models. These approaches can help us understand the mechanisms and outcomes of competition, and can provide insights into how organisms and ecosystems respond to changing environmental conditions and other factors.

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