Niche Theory

The entire set of conditions under which an animal (population or species) can survive and reproduce itself.

• Theoretical Range: It is the maximum possible niche a species can occupy.
• No Competition: Assumes absence of predation or competition.
• Larger: Always larger than or equal to the realized niche.

The set of conditions actually used by a given animal after interactions with other species are taken into account.

• Actual Range: The specific lifestyle the species actually pursues.
• With Competition: Occurs in the presence of predators and competitors.
• Smaller: Usually smaller due to environmental pressure.