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5.2.5Unit 5: Respiration, Internal Environment, Coordination and Gene Technology

Niche — IAL Edexcel Linear Revision Notes & Topical Questions

5 min read 5 parts Lesson 20 of 36 Unit quiz

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Part 1 of 5The Concept

5.2.5 Niche

A niche describes what a species does, not just where it lives.

Definition
  • A niche is the role of a species within its habitat, including its interactions with other species and its environment.
Feeding
  • What the species eats and which species depend on it for food form part of the niche.
Location and time
  • Where the species feeds and lives and the time of day it is active are included.
Habitat
  • The habitat is simply the place where the species lives.
Example
  • Two similar birds may feed on different insects or at different heights in the same tree.

Part 2 of 5Competition and Exclusion

Two species cannot occupy exactly the same niche in the same place.

1
If two species share the same resources, they compete directly with each other.
2
The species that is better adapted to the conditions reproduces more successfully.
3
The less successful species declines until it is absent from that habitat.
4
In experiments with two species of Paramecium sharing one culture, one species outcompeted the other.

Part 3 of 5Abundance and Distribution

Abundance and Distribution
Abundance
  • The number of individuals of a species; it is lower where niches overlap and competition is high.
Distribution
  • Where the species lives; it depends on whether the abiotic conditions suit its niche.
Overlap
  • Species with similar niches reduce each other's populations.
Differences
  • Small differences in diet or timing often allow similar species to coexist.

Part 4 of 5Reducing Competition

Resource partitioning
  • Species feed on different foods or in different parts of the habitat.
Time
  • One species may be active by day and a similar species active at night.
Specialisation
  • Adaptations such as beak shape allow different food sources to be used.
Result
  • Species with different niches can live together in a stable community.

Part 5 of 5Exam Checklist & Tips

5.2.5 – Key Points for the Exam

  • Niche The role of a species in its ecosystem.
  • Competitive exclusion The loss of one species from a habitat because another uses the same resources better.
  • Abundance The number of individuals of a species in a habitat.
  • Distribution The places where a species is found.

Common Mistakes

  • Defining a niche as only where an organism lives.
  • Saying that two species with the same niche will always coexist; one will out-compete the other.
  • Confusing abundance, a number, with distribution, a location.
  • Forgetting that niche includes the species' interactions with other organisms.

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