IB Environmental systems and societies Topic 2.1C Ecological Niche and Population Interactions Revision Notes (SL/HL)

IB Environmental systems and societies Topic 2.1C Ecological Niche and Population Interactions Revision Notes (SL/HL) | RevisionDojo

Written by official IB examiners

The Ecological Niche: A Species' Role, Not Just Its Address

Definition

Ecological niche

An ecological niche is the unique set of abiotic and biotic conditions and resources that a species requires to survive, grow, and reproduce.

Every species has a unique ecological niche, its role and position within an ecosystem.
The niche is the full set of abiotic and biotic conditions a species needs to survive and reproduce.
This covers everything from food sources and temperature tolerance to behaviour and interactions with other species.

Components of a Niche

Habitat: the physical place a species lives, such as a forest floor, coral reef, or tundra.
Feeding habits: what it eats and how it gets food, such as carnivore, herbivore, or detritivore.
Temporal activity: when it is active, whether diurnal, nocturnal, or seasonal.
Interactions: its competition, predation, and mutualistic partnerships.
Physiological range: its tolerance limits for temperature, salinity, pH, and humidity.
Reproductive strategy: its mating behaviour, breeding season, and parental investment.

Analogy

A habitat is the species' address, the place where it lives.
A niche is its occupation, what it does and how it fits into the ecosystem.
Two species can share a habitat, but each still has its own distinct niche.

Describing a Niche in Exams

Exam technique

Always include biotic components: feeding, competition, and predation.
Also include abiotic components: temperature, humidity, soil, and light.

Example

Bengal Tiger (Panthera tigris): A Niche in Detail

Habitat: tropical and subtropical forests, mangroves, and grasslands in South Asia.
Diet: carnivorous, preying on deer, wild boar, and smaller mammals.
Hunting strategy: a solitary ambush predator that hunts at night.
Competitors: other large carnivores such as leopards and dholes.
Abiotic needs: dense cover, water for drinking and cooling, and temperatures of roughly 20 to 40°C.
Ecological role: controls herbivore numbers, helping maintain ecosystem balance.

Fundamental vs Realized Niche

Fundamental niche: the full range of conditions under which a species could survive and reproduce.
Realized niche: the part of the fundamental niche a species actually occupies once competition and other limits are factored in.
The realized niche is usually smaller than or equal to the fundamental niche (HL students develop this fully in 2.1M).

Example

The barnacle Chthamalus can tolerate a wide range of tidal levels, its fundamental niche.
Competition from Balanus confines it to higher tidal zones, its realized niche.

Competitive Exclusion and Resource Partitioning

The competitive exclusion principle, proposed by G.F. Gause (1934), states that no two species can occupy the exact same niche indefinitely in a stable ecosystem.
If two species compete for identical resources, the superior competitor eventually excludes the other.
Species avoid this through resource partitioning, dividing resources in space or time.

Example

Three North American warbler species feed in the same conifers but at different heights.
This partitioning reduces direct competition and lets them coexist.

Population Interactions: Six Ways Species Shape Each Other

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Note

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Tip

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Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

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The Ecological Niche: A Species' Role, Not Just Its Address

Definition

Ecological niche

An ecological niche is the unique set of abiotic and biotic conditions and resources that a species requires to survive, grow, and reproduce.

Every species has a unique ecological niche, its role and position within an ecosystem.
The niche is the full set of abiotic and biotic conditions a species needs to survive and reproduce.
This covers everything from food sources and temperature tolerance to behaviour and interactions with other species.

Components of a Niche

Habitat: the physical place a species lives, such as a forest floor, coral reef, or tundra.
Feeding habits: what it eats and how it gets food, such as carnivore, herbivore, or detritivore.
Temporal activity: when it is active, whether diurnal, nocturnal, or seasonal.
Interactions: its competition, predation, and mutualistic partnerships.
Physiological range: its tolerance limits for temperature, salinity, pH, and humidity.
Reproductive strategy: its mating behaviour, breeding season, and parental investment.

Analogy

A habitat is the species' address, the place where it lives.
A niche is its occupation, what it does and how it fits into the ecosystem.
Two species can share a habitat, but each still has its own distinct niche.

Describing a Niche in Exams

Exam technique

Always include biotic components: feeding, competition, and predation.
Also include abiotic components: temperature, humidity, soil, and light.

Example

Bengal Tiger (Panthera tigris): A Niche in Detail

Habitat: tropical and subtropical forests, mangroves, and grasslands in South Asia.
Diet: carnivorous, preying on deer, wild boar, and smaller mammals.
Hunting strategy: a solitary ambush predator that hunts at night.
Competitors: other large carnivores such as leopards and dholes.
Abiotic needs: dense cover, water for drinking and cooling, and temperatures of roughly 20 to 40°C.
Ecological role: controls herbivore numbers, helping maintain ecosystem balance.

Fundamental vs Realized Niche

Fundamental niche: the full range of conditions under which a species could survive and reproduce.
Realized niche: the part of the fundamental niche a species actually occupies once competition and other limits are factored in.
The realized niche is usually smaller than or equal to the fundamental niche (HL students develop this fully in 2.1M).

Example

The barnacle Chthamalus can tolerate a wide range of tidal levels, its fundamental niche.
Competition from Balanus confines it to higher tidal zones, its realized niche.

Competitive Exclusion and Resource Partitioning

The competitive exclusion principle, proposed by G.F. Gause (1934), states that no two species can occupy the exact same niche indefinitely in a stable ecosystem.
If two species compete for identical resources, the superior competitor eventually excludes the other.
Species avoid this through resource partitioning, dividing resources in space or time.

Example

Three North American warbler species feed in the same conifers but at different heights.
This partitioning reduces direct competition and lets them coexist.

Population Interactions: Six Ways Species Shape Each Other

Definition

Paywall

(on a website) an arrangement whereby access is restricted to users who have paid to subscribe to the site.

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Note

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam quis nostrud exercitation.

Excepteur sint occaecat cupidatat non proident

Tip

Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

Topic 1: Foundation 3 subtopics

Topic 2: Ecology5 subtopics

Topic 3: Conservation and biodiversity3 subtopics

Topic 4: Water4 subtopics

Topic 5: Land2 subtopics

Topic 6: Atmosphere and climate change4 subtopics

Topic 7: Natural resources3 subtopics

Topic 8: Human populations and urban systems3 subtopics

HL lenses 3 subtopics

IB Environmental systems and societies 2.1C Ecological Niche and Population Interactions Notes

Topic 1: Foundation 3 subtopics

Topic 2: Ecology5 subtopics

Topic 3: Conservation and biodiversity3 subtopics

Topic 4: Water4 subtopics

Topic 5: Land2 subtopics

Topic 6: Atmosphere and climate change4 subtopics

Topic 7: Natural resources3 subtopics

Topic 8: Human populations and urban systems3 subtopics

HL lenses 3 subtopics

The Ecological Niche: A Species' Role, Not Just Its Address

Components of a Niche

Describing a Niche in Exams

Bengal Tiger (Panthera tigris): A Niche in Detail

Fundamental vs Realized Niche

Competitive Exclusion and Resource Partitioning

Population Interactions: Six Ways Species Shape Each Other

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account

The Ecological Niche: A Species' Role, Not Just Its Address

Components of a Niche

Describing a Niche in Exams

Bengal Tiger (Panthera tigris): A Niche in Detail

Fundamental vs Realized Niche

Competitive Exclusion and Resource Partitioning

Population Interactions: Six Ways Species Shape Each Other

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account