Ecological Niches & Adaptations (Edexcel International A Level Biology): Revision Note

Niche

• The place where a species lives within an ecosystem is its habitat

• The role that a species plays within its habitat is known as its niche, including:

  • The biotic interactions of the species (e.g. the organisms it feeds on and the organisms that feed on it)

  • The abiotic interactions (e.g. how much oxygen and carbon dioxide the species exchanges with the atmosphere)

• A niche can only be occupied by one species, meaning that every individual species has its own unique niche

• If two species try to occupy the same niche, they will compete with each other for the same resources

  • One of the species will be more successful and out-compete the other species until only one species is left and the other is either forced to occupy a new, slightly different niche or to go extinct from the habitat or ecosystem altogether

• For example, the three North American warbler species shown below all occupy the same habitat (spruces and other conifer trees) but occupy slightly different niches as each species feeds at a different height within the trees

  • This avoids competition between the three species, allowing them to co-exist closely with each other in the same habitat

Although it appears as though these birds share the same niche, they spend their time eating in different parts of spruces and other conifer trees

Adaptations to abiotic and biotic conditions

• Adaptations are features of organisms that increase their chances of surviving and reproducing. These adaptations can be:

  • Anatomical, which refers to structural features such as horns, claws or feathers, that increase an organism's chances of survival

  • Behavioural, which refers to behaviours such as courtship of defensive behaviours, that increase an organism's chances of survival

  • Physiological, which refers to processes inside the body, such as venom production or the ability to digest cellulose, that increase an organism's chances of survival

• A species must be adapted to both the biotic and abiotic factors within its habitat in order to use this habitat in a way no other species can (i.e. in order to occupy its unique niche)

• Examples of adaptations to biotic conditions could include:

Adaptations to Biotic Factors Table

• Examples of adaptations to abiotic conditions could include:

Adaptations to Abiotic Factors Table