The concept of niche

Energy Flow, Ecosystems and the Environment · Productivity and ecosystems · note 4 of 6

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The concept of nicheSpec 5.13

In short

A niche is the role of a species in its habitat: what it eats, where and when it is active, and how it interacts with other organisms and the abiotic environment. Two species cannot share the same niche in one habitat for long, because one outcompetes the other. Niche helps explain where organisms are found and how many there are.

Niche: The role of a species within its habitat, including its interactions with the biotic and abiotic components of the environment (for example its food, its habitat, its time of activity and its position in the food web).

Each species has a unique niche. Within a habitat, the niche of a species is shaped by its adaptations: where it feeds, what it feeds on, the abiotic conditions it tolerates, when it is active and how it reproduces.

How niche accounts for distribution and abundance

A species is found only where the biotic and abiotic conditions of its niche are met, which explains its distribution.
If two species have very similar niches, they compete for the same resources. This interspecific competition reduces the population of both, or one species outcompetes the other and is excluded from the habitat (the competitive exclusion principle).
Coexisting species usually have slightly different niches, for example feeding at different heights, on different foods or at different times of day. This reduces competition and allows more species to live in the habitat.
Within a species, intraspecific competition for the resources of its niche limits the population size, so the amount of the resources in the habitat sets the abundance of the species.

For example, two species of birds may both eat insects from the same tree. If one feeds mainly on the trunk and the other on the outer twigs, their niches differ enough for both to survive, and the abundance of each reflects the food in its part of the tree.

Common mistake:

Habitat and niche are not the same. A habitat is where an organism lives; a niche is what it does there and how it interacts with its environment.

Written and checked against the Edexcel International A Level Biology (YBI11) specification · Updated October 2026

Frequently asked questions

What is the difference between GPP and NPP?

Gross primary productivity is the total chemical energy fixed by plants in photosynthesis. Net primary productivity is the energy left after the plants’ own respiration is subtracted (NPP = GPP − R). NPP is the energy stored as new biomass and available to the next trophic level.

Why is energy transfer between trophic levels inefficient?

Only a small fraction passes on because energy is lost in respiration as heat, in egested faeces, in excretory products such as urea and in parts that are not eaten, such as bone. These losses leave less energy available at each successive trophic level.

What is the difference between a habitat and a niche?

A habitat is the place where an organism lives. A niche is the role of the species in that habitat, including what it feeds on, when it is active, the conditions it tolerates and how it interacts with other organisms. Species in the same habitat have different niches.

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