Habitat and Niche

Habitat and niche are two of the most commonly confused terms in ecology, but they describe genuinely different things. A habitat is the specific physical place — the actual address — where an organism lives, characterised by a particular combination of abiotic (soil, climate, moisture) conditions; the environment of an entire community, taken together, is called a biotope. A niche, in contrast, is not a place at all but a functional role — the sum of everything an organism does for a living within its ecosystem: what it eats, what eats it, how it reproduces, what resources it competes for, and what its physiological tolerances are. The term 'niche' was coined by the naturalist Roswell Hill Johnson, though Grinnell (1917) is usually credited as the first to use it formally. The combination of an organism's habitat and its niche together is called its ecotope. The practical differences follow directly from these definitions: many different species can share the very same habitat (a pond, say, is 'home' to fish, algae and insects all at once), but a single niche within an ecosystem is typically occupied by only one species at a time, since two species trying to do exactly the same job in exactly the same place tend to end up competing until one excludes the other. Likewise, organisms usually show str …