Niche (Edexcel International A Level Biology): Revision Note

The Concept of Ecological Niche

• The place where a species lives is known as its habitat

• Species will occupy a specific niche within a habitat

• The term niche can be defined as the role of a species within its habitat

• The role of a species includes

  • What it eats

  • Which other species depend on it for food

  • What time of day a species is active

  • Exactly where in a habitat a species lives

  • Exactly where in a habitat a species feeds

• No two species can fill the same niche within a habitat; if this ever happens the two species will be in direct competition with each other for resources, and one of the two species will out-compete the other, causing it to die out in that particular habitat

  • It can sometimes seem as though species are occupying the same niche, but there will still be subtle differences in their role; e.g. they might feed at different times of day, or have different food sources

• The niche filled by a species determines its abundance within a habitat

  • The term abundance can be defined as the number of individuals of a particular species living in a habitat

  • If two species occupy a similar niche within a habitat they will be competing with each other, so their populations will be smaller, and their abundance will therefore be lower

• The niche filled by a species determines its distribution

  • The term distribution can be defined as where a species lives

  • Species can only survive in habitats to which they are well adapted; if they are not well suited to a habitat's biotic and abiotic factors then they will move to a more suitable habitat and their distribution will change

Feeding location is an example of a feature that may differ between niches.