A keystone species is a species that has a disproportionately large effect on its natural environment relative to its abundance. The concept was introduced in 1969 by the zoologist Robert T. Paine. Keystone species play a critical role in maintaining the structure of an ecological community, affecting many other organisms in an ecosystem and helping to determine the types and numbers of various other species in the community. Without keystone species, the ecosystem would be dramatically different or cease to exist altogether. Some keystone species, such as the wolf and lion are also apex predators.
The jaguar: a keystone, flagship, and umbrella species, and an apex predator
The beaver: a keystone species, and habitat creator, responsible for the creation of lakes, canals and wetlands irrigating large forests and creating ecosystems
Ochre seastars (Pisaster ochraceus), a keystone predator
California mussels (Mytilus californianus), the seastar's prey
In ecology, a community is a group or association of populations of two or more different species occupying the same geographical area at the same time, also known as a biocoenosis, biotic community, biological community, ecological community, or life assemblage. The term community has a variety of uses. In its simplest form it refers to groups of organisms in a specific place or time, for example, "the fish community of Lake Ontario before industrialization".
A bear with a salmon. Interspecific interactions such as predation are a key aspect of community ecology.
a) A trophic pyramid showing the different trophic levels in a community. b) A food web of the same community
A red-chested cuckoo chick being feed by a significantly smaller Cape robin-chat adult
