What is the Difference Between Fundamental and Realized Niche?

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The fundamental niche and realized niche are concepts in ecology that describe the environmental position of a species in an ecosystem. They are defined as follows:

  • Fundamental Niche: This refers to the entire set of conditions under which a species can survive, reproduce, and thrive. It represents the ideal conditions where a species can live and takes advantage of all biotic and abiotic factors in an ecosystem without any competition or predation.
  • Realized Niche: This is the set of conditions actually used by a given species after interactions with other species, such as competition and predation, have been taken into account. The realized niche is the area where a species actually lives, and it is typically smaller than the fundamental niche due to the presence of other organisms competing for resources.

Some key differences between fundamental and realized niches include:

  1. Size: Fundamental niches are larger than realized niches, as they represent the ideal conditions for a species to thrive without any competition or predation. The realized niche is smaller due to the presence of other organisms competing for resources.
  2. Competition: In the fundamental niche, there is no competition for resources or predators, while in the realized niche, the species faces competition for resources and predation.
  3. Specialist vs. Generalist: Specialist species have narrow niches, meaning they thrive only in specific conditions, while generalist species have broad niches and can adapt to a variety of conditions. The fundamental niche might be wider for a specialist species, but the realized niche can be narrow due to competition.
  4. Location: The fundamental niche represents the environmental conditions where a species can live, while the realized niche is where the species actually lives. This can differ depending on the presence of other species and competition for resources in a particular area.

In summary, the fundamental niche represents the ideal conditions for a species to thrive without any competition or predation, while the realized niche reflects the actual conditions a species experiences in an ecosystem with other species competing for resources.

Comparative Table: Fundamental vs Realized Niche

Here is a table comparing the differences between fundamental and realized niches:

Feature Fundamental Niche Realized Niche
Definition The entire set of conditions under which an organism can survive and reproduce, with no competition for resources or predators. The actual environment where a species lives and interacts with other species, with competition for resources and predators.
Size Larger. Smaller.
Role Pre-competitive niche, ideal conditions for the species. Post-competitive niche, where the species actually lives and adapts to the presence of other species.
Environment Theoretical, no limiting factors on the environment or resources. Actual, where the species lives and faces competition from other species.
Breadth Specialist species have narrow niches, generalist species have broad niches. Specialist species have small niches, generalist species have larger niches.

In summary, the fundamental niche represents the ideal conditions where a species can thrive without competition, while the realized niche is the actual environment where the species lives and interacts with other species, taking into account competition for resources and predators.