What best describes an ecological niche?

An ecological niche refers to the specific role and position a species occupies in its environment, encompassing how it meets its needs for food, shelter, and reproduction. This concept includes the species' interactions with other organisms, both biotic (living) and abiotic (non-living) components of the ecosystem.

Choosing the correct answer highlights that the ecological niche is not merely about where an organism lives but delves deeper into the functional aspects that dictate how it survives and thrives in its habitat. This includes its behavior, the resources it utilizes, and the environmental conditions it can tolerate. Understanding a species' niche allows ecologists to comprehend its contributions to the ecosystem, such as its role in food webs, nutrient cycling, and the impacts of environmental changes on populations.

In contrast, the other options focus on different aspects. The physical characteristics of a species address morphology and anatomy rather than its ecological function. The genetic makeup pertains to the inheritance and variation of traits within a species, which does not define its role in the ecosystem. Population size relates to species abundance and distribution but does not encapsulate the comprehensive role that a species plays within its habitat.