Biology • Ecology

Fundamental Niche

What could a species use if competition and other biological interactions did not restrict it?

What Is a Niche?

A species' niche describes how it interacts with its environment and uses the resources available to it. A niche includes more than simply the physical place where an organism lives.

An organism's niche can involve factors such as food, water, temperature, shelter, light, space, and interactions with other organisms.

Habitat = where an organism lives.

Niche = how an organism lives and uses its environment.

What Is the Fundamental Niche?

The fundamental niche is the full range of environmental conditions and resources that a species could potentially use when biological interactions with other species are not restricting it.

Fundamental niche = the potential range of conditions and resources a species can use.

Think of the fundamental niche as the species' potential ecological range. It describes what the organism could use based on its physiological tolerances and resource requirements.

This does not necessarily mean that the organism actually uses every part of this range in nature.

What Determines a Fundamental Niche?

A species' fundamental niche is influenced by the environmental conditions it can tolerate and the resources it requires.

Abiotic Factors

Physical Conditions

Temperature, moisture, salinity, pH, light intensity, and other physical or chemical conditions can determine where a species can survive.

Resources

What It Needs

Food, water, nutrients, shelter, space, and other resources help define the conditions a species could potentially use.

Competition and the Niche

Other organisms can prevent a species from using all of the conditions and resources that fall within its fundamental niche.

Competition is especially important when two species depend on the same limited resource.

If competitors are removed: a species may be able to use a larger portion of the conditions and resources it can tolerate.

If competitors are present: the species may actually occupy a smaller range.

Fundamental Niche vs. Realized Niche

The fundamental niche and realized niche are closely related concepts, but they answer different questions.

Potential range compared with actual range

Fundamental niche

Realized niche

The realized niche may occupy only part of the fundamental niche because of ecological interactions.

The fundamental niche describes what a species could potentially use. The realized niche describes what it actually uses under real ecological conditions.

Fundamental = potential.
Realized = actual.

An Example

Imagine a bird species that can survive across a broad range of forest conditions and can eat several different types of insects.

In the absence of competing bird species, it might be capable of feeding throughout a large portion of the forest and using several different food sources.

Now imagine another bird species that relies on some of the same insects and feeding locations. Competition may prevent the first species from using all of the resources it could otherwise use.

The larger potential range represents the fundamental niche. The smaller range actually used in the presence of competition represents the realized niche.

Common Misconceptions

“A niche is the same thing as a habitat.”

A habitat describes where an organism lives. A niche includes how it lives, what resources it uses, and its ecological role.

“Fundamental niche means where the organism actually lives.”

Fundamental niche describes the potential range. The actual range occupied under real ecological conditions is the realized niche.

“Competition creates the fundamental niche.”

Competition can restrict the range a species actually occupies. The fundamental niche represents what the species could potentially use without those biological restrictions.

“The fundamental niche is always smaller than the realized niche.”

The realized niche is generally a portion of the fundamental niche, rather than a larger range.

If You See This on a Test...

“The full range of conditions a species could potentially tolerate”
→ Fundamental niche

“The range of resources a species could use if competitors were absent”
→ Fundamental niche

“A species can survive in a wider range than it actually occupies”
→ Fundamental niche is larger than realized niche

“Competition prevents a species from using part of its potential range”
→ Think fundamental vs. realized niche

Quick Practice

Define fundamental niche in your own words.
How is a niche different from a habitat?
Name two abiotic factors that could influence a species' fundamental niche.
A species can survive in a wide range of temperatures but occupies only a narrow temperature range in nature because of competition. Which niche describes the wider range?
Why can competition reduce the portion of a niche a species actually uses?
Which term describes the actual range of conditions and resources a species uses in nature?

Key Takeaways

A niche describes how a species uses its environment and its ecological role.
The fundamental niche is the full potential range of conditions and resources a species could use.
Abiotic conditions and resource requirements help determine a species' fundamental niche.
Competition and other biological interactions can restrict what a species actually uses.
The realized niche is the portion of the potential niche actually occupied under real ecological conditions.
The simplest distinction is: fundamental = potential; realized = actual.