Explain how resource partitioning allows ecologically similar species to coexist within the same community.

IB DP Biology Standard Level (2023 syllabus) — C4.1 Populations and communities · Explain · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Model answer (4 marks)

Ecologically similar species that compete for the same resource would normally experience competitive exclusion, preventing coexistence.
Resource partitioning divides the shared resource so that each species uses a different portion, for example different times, places or sizes of food.
This reduces niche overlap, so inter‑specific competition is minimised.
Consequently each species can maintain a viable population and long‑term coexistence is possible within the community.

Examiner tips

  • Use the word "resource partitioning" early. Explain the mechanism (different parts of the resource) and link it to reduced competition. Show the causal chain: partitioning → less overlap → less competition → coexistence.

Common mistakes

  • Confusing resource partitioning with competitive exclusion. Failing to mention that partitioning reduces niche overlap. Using vague terms like "diversity" instead of specific mechanisms.

Mark scheme (4 marks)

  1. Ecologically similar species competing for the same resource would experience competitive exclusion, preventing coexistence.
  2. Resource partitioning is the division of a shared resource so that different species use different portions of it, reducing direct competition.
  3. This reduces niche overlap, so interspecific competition is reduced/minimised.
  4. As a result, each species can maintain a viable population without being excluded, enabling long-term coexistence in the community.

Key terms in this question

resource partitioning

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