In ecology, a niche is a term describing the relational position of a species or population in an ecosystem.
More formally, the niche includes how a population responds to the abundance of its resources and enemies (e. g., by growing when resources are abundant, and predators, parasites and pathogens are scarce) and how it affects those same factors (e. g., by reducing the abundance of resources through consumption and contributing to the population growth of enemies by falling prey to them).
The abiotic or physical environment is also part of the niche because it influences how populations affect, and are affected by, resources and enemies.
The description of a niche may include descriptions of the organism's life history, habitat, and place in the food chain.
According to the competitive exclusion principle, no two species can occupy the same niche in the same environment for a long time.