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Competition of Organisms for Limited Resources

Grade 7
May 31, 2023

Introduction to Competition of Organisms for Limited Resources


When two entities oppose each other for the desired outcome, it can be called competition. Competition can be seen at work in our everyday lives, like rivaling athletics, commercial product markets, etc. Competition happens when the two parties want the same thing, but there is not enough of it to go around.


What do Organisms Compete For?

There is competition for limited resources like air, water, food, and space among organisms.

There is comfortable co-existence when the resources are sufficient, while the ecosystem boasts high species richness (diversity) where they are abundant.


An organism has better chances to co-exist with its conspecifics (other members of the same species) if it is more generalist.

Those animals and plants have a more difficult life competing with specific life history requirements, like cavity-nesting birds, plants with pH-specific soil requisites, or animals with obligate feeding behaviours.

Types of Competition

The competitive exclusion principle is the fundamental concept in ecology which states that two species with similar ecological niches cannot exist in the same environment.

Interspecific and Intraspecific Competition

Interspecific competition occurs when various creatures living in the same geographic area, such as sympatric species, compete for the same set of resources, primarily food and space.

Interspecific competition


On the other hand, when the same species compete with each other, usually for more specific requirements like mates and nesting/denning sites, it is called Intraspecific competition.

Intraspecific Competition

Direct and Indirect Competition

When individuals compete directly for the same resource with each other, it is known as direct competition.

For example, two bull moose battling for access to a single female.

Indirect competition is when organisms use the same resource but don’t necessarily interact with each other.

For example, diurnal cheetahs and nocturnal leopards use the same waterhole in a grassland savanna.

Interference and Exploitation Competition

Interference competition is defined as the deliberate displacement of individuals by a competitor.

In this type of competition, the less competitive individuals are forced to go elsewhere to find resources, and if the more competitive animals leave, the displaced individuals will return.

Exploitation competition is when a species’ survival or reproduction is suppressed because of the presence of a staunch competitor.

In this type of competition, there is no actual displacement, as competitive pressure manifests itself through a reduction in an individual’s ability to survive and reproduce.

Forces of Competition

Defensive Behavior

When space is found by an animal that contains all the resources it needs to survive, it tends to hold onto it.

For this reason, many animals are territorial; they defend their territory containing those resources.

Different types of resources that an animal tends to defend are a convenient source of fresh water, an ample supply of vegetation, proximity to a stable source of prey, denning sites, etc.

Defensive Behavior

Aggressive Behavior

When their resources are compromised, animals exhibit aggressive behaviour.

For example, males may compete over an existing territory, available females, nesting sites, or breeding rights in a social hierarchy.

If problems cannot be resolved by threatening displays or intimidation, defensive behavior might lead to aggression.

Aggressive Behavior

Competition of the Herbivorous Kind

Competition doesn’t only occur in the animal world; plants too compete with each other for limited resources like adequate sunlight, soil nutrients, and freshwater to survive. With time, plants have evolved ingenious ways of procuring sunlight, attracting pollinators and obtaining fresh water. An offensive approach may also be taken, responding to the competition head-on, or a defensive approach, making modifications to increase their chances of survival and reproduction.

For example, some forest trees grow rapidly to tower over their competitors and absorb the most sunlight when sunlight is the limiting factor. Others, on the other hand, focus their efforts on producing a large number of seeds and spreading them so that their offspring have a better chance of landing in a well-lit environment. Plants have developed a variety of competitive strategies, ranging from storing resources to becoming parasites to acquiring disease resistance.

How to Avoid Competition – Isolate Yourself

There are mainly three kinds of isolation:

  • Geographic isolation
  • Behavioural isolation
  • Mechanical isolation

Geographic Isolation

One method of isolation is geographic isolation, i.e., not being in the same place at the same time. The animals have a better chance of obtaining the resources they need. Animals can have different geographic distributions or participate in seasonal migrations. It might be an expanse of land, a mountain range, a body of water, or an elevation gradient.

Geographic Isolation

Behavioural Isolation

It takes place when animals have contradictory behaviours that prevent them from competing with each other. Example: By day, birds rule the air by foraging, maintaining territories, reproducing, and competing for the best available resources. By night, however, bats rule the roost. At dusk, when the diurnal (active by day) species retire for the evening and the nocturnal (active by night) organisms begin their daily follies, there is a taxonomic tango.

Mechanical Isolation

An evolutionary expression of a behavioural trait is the lip morphology of rhinos that separated them long ago.

Many animals today have morphological differences that directly allow them to avoid competition with other organisms.

Giraffes, for example, have a browse line far higher than the other browsers it resides with, and hyenas have jaw structures and musculature powerful enough to ingest the hides and bones of carcasses left behind by other predators.

Competition of organisms with each other for limited resources


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