In ecology, what is a niche?

A niche refers to the role or function of a species within its ecosystem, encompassing how it interacts with other organisms and its environment. This includes its habitat, resource use, behaviors, and the ecological relationships it engages in, such as predation, competition, and symbiosis. The concept of a niche illustrates how a species contributes to the overall structure and dynamics of the ecosystem, including its position in the food web and how it fulfills specific functions that allow it to survive and reproduce.

Understanding a species' niche is crucial for comprehending biodiversity and ecosystem health, as it shows how different organisms coexist and contribute to the ecological balance. In contrast, the other options focus on aspects like population size, genetics, or the physical environment, which do not capture the comprehensive biological and ecological roles that define what a niche truly represents.