B4.2 Ecological niches (Ecosystems): Practice Questions

Which of the following describes the set of conditions and resources under which a species can survive and reproduce in the absence of competition and predation?

Which of the following best defines the ecological niche of a species?

Two sympatric species of carnivorous caddisfly larvae live in the same fast-flowing stream. Both species capture prey using spun silk capture nets. A detailed study of net architecture revealed the following data:

• Species A spins a fine mesh net (pore diameter \(40\text{–}60\,\mu\text{m}\)) in low-velocity eddy currents, capturing small algae and micro-invertebrates.
• Species B spins a coarse mesh net (pore diameter \(200\text{–}300\,\mu\text{m}\)) in high-velocity riffles, capturing large insect fragments and amphipods.

How does this structural and microhabitat differentiation facilitate the stable coexistence of both caddisfly species?

What occurs when two species occupy the same niche and compete for the same limited resources?

A specific species of bird feeds on insects found only in the canopy of a rainforest. If a new competitor species is introduced that also feeds in the canopy, the original bird species begins to feed only on the lower branches. What has changed for the original bird species?

State the biological principle which proposes that two species competing for the exact same limiting resources cannot stably coexist in identical niches.

Explain how the presence of a competitor can lead to a difference between a species' fundamental niche and its realized niche.

Explain how an abiotic disturbance can prevent competitive exclusion and allow multiple species with heavily overlapping fundamental niches to coexist.

Ecological niches describe how organisms interact with biotic and abiotic factors in their environment.

a) Define the term ecological niche.
b) Distinguish between a fundamental niche and a realized niche.
c) State the principle which predicts that two species competing for the exact same limited resources cannot stably coexist indefinitely.

Two species of birds inhabit the same forest. Species A feeds on insects found in the upper canopy, while Species B feeds on insects found on the forest floor.

a) State the term used to describe the specific functional role and position of a species within its environment.
b) Explain how the competitive exclusion principle relates to the observed distribution of these two bird species.
c) Distinguish between spatial and temporal niche partitioning.