One difference between a fundamental niche and a realized niche is that the fundamental niche is always larger the realized niche is the preferred niche the fundamental niche is always smaller the realized niche may be less extensive

Size

Explanation:

We can define niche as particular place where certain things exist. This is a very broad term and it can refer to a particular workplace for a particular society or it can be referred to as a specific role taken by an organism in a certain community.

If we talk about ecological niches they can be either fundamental niche or realized one. Both describe how organisms living in a particular zone interact with their environment and community, however, the difference between both is their size.

Fundamental niche cover all the conditions which a specific organisms need for its survival like temperature, precipitation, sunlight, food etc.

However, Realized niche covers only those conditions which are in actual used by a specific organisms while interacting with other organisms. For example: Competition for food and resources, predation to get food etc.

Therefore, it is quite evident that Fundamental niche is larger in size than realized niche.

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