1. A summary of the conditions and resources that must be available in order for a species to maintain a population in the long term. A niche therefore is not a place but a conceptual volume with numerous dimensions (an n-dimensional hypervolume), such as temperature, humidity, and food supply, each defined by the tolerable range for that particular species. This concept of niche is based on a proposition made in 1957 by British-born US zoologist G. E. Hutchinson (1903–91) and has subsequently been refined and widely adopted. The fundamental niche of a species describes its potential hypervolume; this is determined principally by the physiological characteristics of the species and is generally transferable from place to place. However, the realized niche is the more limited hypervolume that a species can occupy when the effects of competition, predation, and parasitism by other species are considered. According to the competitive exclusion principle, two species cannot occupy the same ecological niche in both space and time.

2. The status or role of an organism in its environment.