Ecological Niche

The term ecological niche was first used by J. Grinnell (1917) to denote the functional role played by an organism in its environment. A niche covers every aspect of how an organism makes its living -- its diet, its shelter requirements, and so on -- and describes how the organism is linked to both its physical and biological surroundings. A convenient way to remember the distinction is that, in everyday language, a habitat is an organism's postal address, while a niche is its profession. Because niche is fundamentally about the flow of energy from one organism to another, understanding a species' niche means understanding what it eats and how it interacts with the other organisms around it. As soon as a niche becomes vacant -- for instance, if the species occupying it disappears -- some other organism will move in to fill that position, because no two species can occupy exactly the same niche at the same time.

Ecologists recognise three ways of thinking about niche: (a) the spatial or habitat niche, which is about the physical space an organism occupies; (b) the trophic niche, defined by the organism's position or level in a food chain; and (c) the multidimensional or hypervolume niche, which considers many environmental factors -- both biotic and abiotic -- simultaneously, producing a theoretical 'hypervolume' too complex to be visualised directly by the human mind; equivalently, this is the organism's position along the overall environmental gradient. …