is the species responsible for the structure and integrity of an ecosystem. The term was first coined by ecologists in the late 1960s ( Paine, 1969).

Organisms that play dominant roles in an ecosystem and affect many other organisms. The removal of a keystone predator from an ecosystem causes a reduction of the species diversity among its former prey. [Go to source

The concept that only one or a few species have uniquely important effects of the community or ecosystem by virtue of unique traits or attributes. The removal of a keystone species, like the removal of a keystone from an arch, results in dramatic changes in the functional properties of the ecological system, e.g. changes in diversity, abundance or habitat structure. See Heywood (1995).

A species that is of exceptional importance in maintaining the species diversity of a community; when a keystone species is lost, the diversity of the community decreases and its structure is significantly altered.

An animal that is crucial to its niche, or habitat. Some tarantulas are keystone species due to their diets.

a species that is disproportionately important in the maintenance and balance of its community integrity

A species that interacts with a large number of other species in a community, and whose removal of this species may cause widespread changes to community structure.

Species that play a pivotal role in the abundances and distributions of other species in a natural community (Ecology of Atlantic Shorelines 1999).

Species that interacts with a large number of other species in a community. Because of the interactions, the removal of this species can cause widespread changes to community structure. Compare with immigrant species, indicator species, and native species.

a species that plays a fundamental role in maintaining the plants and animals in an ecosystem.

Species that have a key role in the ecosystem.

A species of animal on which associated animals depend for support. (For example, starfish are keystone species off the coast of British Columbia. They feed on clams which would otherwise eat all other sea animals in the region. If starfish are removed, the clams flourish, and the marine animal population plunges.)

A species whose impacts on its community or ecosystem are much larger and more influential than would be expected from mere abundance. This could be a top predator, a plant that shelters or feeds other organisms, or an organism that plays a critical ecological role. [Go to source

Species crucial to the interactions, and overall health, of a given ecosystem.

a dominant species that can dictate community structure

a species on which the persistence of a large number of other species in the ecosystem depends

a species that exerts great influence on an ecosystem

a species that has a major influence on the structure of an ecosystem

a species that has strong regulatory effects on the composition of the community, even through it may be in relatively low abundance compared to other members of the community

a species that other species depend upon for survival

a species that plays an essential role in the structure, functioning or productivity of a habitat or ecosystem at a defined level (habitat, soil, seed dispersal, etc)

a species whose very presence contributes to a diversity of life and whose extinction would consequently lead to the extinction of other forms of life

a species that has a larger impact on its community or ecosystem than would be expected from its abundance.

a plant or animal species that many other organisms in a community depend on, such as the American Chestnut before the chestnut blight.

A species whose relative abundance in an ecosystem is used to gauge the overall health of that ecosystem.

A species upon which several other species depend. Removal of the keystone species leads to the death or disappearance of the dependent species.

A species whose loss from an ecosystem would cause a greater than average change in other species populations or ecosystem processes. (See: " Biodiversity Loss: Cascade Effects and " Biodiversity Conservation and Forest Management.")

A species that has a major influence on community structure.

A species whose loss from an ecosystem would cause a greater than average change in diversity or abundance of other species, community structure, and/or ecosystem processes. The original concept of keystone species was applied to predators who could have such impacts. Over time the term has been applied to species at all trophic levels, and new terminology is evolving for these species based on their mode of action or behavior. Under the broadly applied definition, many consider oysters to be a keystone species.

a species that has a central servicing role affecting many other organisms and whose demise is likely to result in the loss of a number of species and lead to major changes in ecosystem function

Critical species in a n ecosystem whose loss profoundly affects several or many other species.

A species which can structure the composition of an entire shore.

An organism in the ecosystem that many other species depend upon for continued survival and support. Salmon are keystone species because when they die they supply many species with energy and nutrients, which are cycled throughout the ecosystem again and again.

A species which, if removed from an ecosystem, causes a dramatic change in the system, and which has been proposed as an indicator of the functional capacity of the system.

a species having a major influence upon community structure, often in excess of that expected from its relative abundance

A species that influences the ecological composition, structure, or functioning of its community far more than its abundance would suggest.

A plant or animal that plays a more significant role in the habitat than other species; they provide essential services that are unique. Without the work of these key species, the habitat will change significantly.

n: Species that play roles affecting many other organisms in an ecosystem.

species that are essential to the survival of many others within an ecosystem.

A keystone species is a species that has a disproportionate effect on its environment relative to its abundance. Such an organism plays a role in its ecosystem that is analogous to the role of a keystone in an arch. While the keystone feels the least pressure of any of the stones in an arch, the arch still collapses without it.