Niche (Ecology) — Definition & Examples

Ecological Niche

A niche is a species' ecological role in its community. It's determined by many factors. These include the conditions the organism can tolerate and the resources it needs. Its interactions with other species also plays a role. You can think of it kind of like Goldilocks and the Three Bears:

In this analogy, Goldilocks is the species and the branches are the niches. Just like in the story, one branch is too thin to support the goldfinch. One is too thick, and one is just right. Organisms have evolved over time to fit into their niches.

Fundamental Versus Realized Niche

For any organism, there are certain resources it could use. There is also a range of possible habitats it could live in. We call this a fundamental niche.

The realized niche is the resources and habitat that the species is actually able to use.

A population's realized niche is usually way smaller. This can be due to competition within the same species (intraspecific). There might also be competition between species (interspecific). Predators or even a lack of resources can have an effect as well.

(Video) Ecology: What Is a Niche?

by FuseSchool - Global Education

An organism's need for resources defines where it uses its energy. This determines what niche it fits into.

Organisms and their Niches

You know how you have that comfy couch you don't want to leave? Organisms are the same way. Organisms have spots in their communities where they are most comfortable. Without these spots, all living things would be fighting each other to survive all the time. Instead, organisms have special adaptations to fit in their environments. This way, they no longer have to fight for what they need.

Fun fact: When there are suddenly a lot of unoccupied niches, a species can rapidly adapt to take advantage of them. This is called adaptive radiation. A famous example you may have heard of is Darwin's Galápagos finches.

What Is a Niche?

This is an organism's environment as well as its role within that environment.

This includes what the organism eats and where it lives. It also includes how it behaves and interacts with other organisms in the community. Finally, it also includes roles in energy flow and matter recycling in the ecosystem.

Fundamental Niches

Every person has a million possible choices in their lives. Some examples are what we eat, where we live, and the job we want. These are all options that contribute to our fundamental niche. For any organism, this includes all the possible options it has. These could be resources, behaviors, or interactions within the environment.

Realized Niches

Sadly, there are a lot of limits to our choices. A medical condition might limit your diet. Financial troubles could limit where you can live.

In nature, organisms are often limited by interactions with other species, like competition or predation, and by their changing environment. These obstacles create a more specific realized niche. This is the real-life habitat and resources that an organism utilizes.

Competitive Exclusion

Niches need to be restricted because no two species can have the exact same one. This is because they would both have the same needs and use the same resources. This is why organisms compete for resources instead. One species will out-compete the other and take control of the resource. We call this competitive exclusion.

Resource Partitioning

Imagine this other case: Two species may end up sharing a niche by alternating use of a resource. We call this resource partitioning. For example, two species can use the same food source within the same habitat. However, they can each stick to different parts of the habitat when looking for food. Instead of competing for that food source, they divided up the region. Now they can both stay in the same niche.

An organism's niche includes its environment, behaviors, and interactions. It also includes its role within the environment.

The environment consists of living and nonliving components. However, the natural world is much more complex than that. Every organism has an impact on other organisms through interactions like competition. Similarly, living things change the abiotic composition of an environment. For example, humans constantly change the environment by depleting abiotic factors. These include resources like water and coal.

All the things an organism does within its ecosystem is called its niche.

This includes what it eats, what eats it, how it behaves, and what larger impact it has on its ecosystem.