Range Of Tolerance Determines Fundamental And Realized Niches
- Living organisms exist within specific ranges of biotic (living) and abiotic (non-living) conditions, which define the limits of their survival.
- Beyond these ranges, the species cannot thrive due to insufficient adaptations.
- This survival range is referred to as the species’ range of tolerance, which forms the foundation for understanding ecological niches.
Note
An ecological niche is not just the physical space a species occupies (its habitat) but also its interactions and functional role within the environment.
Fundamental Niche Is The Theoretical Potential
Definition
Fundamental niche
The fundamental niche represents the full range of environmental conditions and resources a species could theoretically occupy if there were no competition, predation, or other biotic limitations.
- This means if a species lived in an environment free from competition, it would occupy its entire fundamental niche.
- It is shaped by the species’ adaptations, such as:
- Physiological tolerances (e.g., temperature range a species can survive in).
- Behavioral traits (e.g., foraging strategies).
- Reproductive strategies (e.g., seed dispersal mechanisms).
Example
- If a plant species is capable of thriving across a wide range of soil pH levels, its fundamental niche spans that entire range.
- However, other plant species competing for resources might restrict its actual presence
Realized Niche Is The Reality of Competition
Definition
Realized niche
The true extent of a species’ presence in an ecosystem.
- In natural ecosystems, organisms seldom occupy their fundamental niches.
- Factors that constrain the realized niche include:
- Competition for limited resources, restricting their available space or food supply.
- Predation that force species into safer, but less ideal habitats.
- Mutualistic relationship where some species rely on specific pollinators or symbiotic partners that limit their distribution.
Example
- Two bird species competing for nesting sites
- One species might be forced to nest in tall trees, while the other uses shrubs.
- Their realized niches are now narrower than their fundamental niches.
Self review
- What is the key difference between a fundamental niche and a realized niche?
- How does competition influence the realized niche of a species?
- Can you think of an example in your local environment where two species compete, narrowing their realized niches?
