B4.2.13—Competitive exclusion
Competitive exclusion occurs when species with strongly overlapping niches compete for limiting resources until one is excluded locally from the niche.
- Syllabus
- First assessment 2025
- Objective
- B4.2.13
- Level
- SL
Exam analysis
Chance of appearing5%of analysed past papers
Latest appearanceMay 2025
Most common paperPaper3
Typical marks2–3
Common command terms
- Explain
- Outline
- Describe
Scoring notes
- Common mistake
- Saying competitive exclusion always means worldwide extinction rather than local exclusion from a niche.
Recent exam appearances
May 2025Paper1A ["SL"] · TZ227[ 1 ]B4.2.13—Competitive exclusion
November 2020Paper3 ["SL"] · TZ012(b)[ 2 ]B4.2.13—Competitive exclusion
May 2019Paper3 ["SL"] · TZ114[ 4 ]B4.2.13—Competitive exclusion
May 2018Paper3 ["SL"] · TZ113(b)[ 2 ]B4.2.13—Competitive exclusion
November 2016Paper3 ["SL"] · TZ011(c)[ 3 ]B4.2.13—Competitive exclusion
Practice this objective
Coverage 2012–2025 · Updated 15 Jul 2026
Concept essentials
- Two species cannot occupy identical niches indefinitely when resources are limiting.
- Greater niche overlap increases interspecific competition.
- The better competitor may exclude the other species locally.
- Paramecium mixed-culture data can demonstrate competitive exclusion.