What is keystone species

The results have been noteworthy. Elk populations have shrunk, willow heights have increased, and beaver and songbird populations have recovered. Herbivores can also be keystone species. Their consumption of plants helps control the physical and biological aspects of an ecosystem. In African savannas such as the Serengeti plains in Tanzania, elephants are a keystone species.

Elephants eat shrubs and small trees, such as acacia , that grow on the savanna. Even if an acacia tree grows to a height of a meter or more, elephants are able to knock it over and uproot it.

This feeding behavior keeps the savanna a grassland and not a forest or woodland. With elephants to control the tree population, grasses thrive and sustain grazing animals such as antelopes, wildebeests, and zebras. Smaller animals such as mice and shrews are able to burrow in the warm, dry soil of a savanna. Predators such as lions and hyenas depend on the savanna for prey. Keystone mutualists are two or more species that engage in mutually beneficial interactions.

A change in one species would impact the other, and change the entire ecosystem. Keystone mutualists are often pollinators, such as bees. Pollinators often maintain gene flow and dispersal throughout widespread ecosystems.

In the woody grasslands of Patagonia at the southern tip of South America a species of hummingbird and indigenous plants act together as keystone mutualists. Local trees, shrubs, and flowering plants have evolved to only be pollinated by Sephanoides sephanoides , a hummingbird known as the green-backed firecrown. Pockets of the existing Patagonian habitat would collapse without green-backed firecrowns, because their functional redundancy is nearly zero—no other pollinator has adapted to pollinate these plants.

In addition to keystone species, there are other categories of organisms crucial to their ecosystems' survival. Umbrella species are often conflated with keystone species. Both terms describe a single species on which many other species depend. The key distinction between umbrella species and keystone species is that the value of an umbrella species is tied to its geographic species range.

Umbrella species have large habitat needs, and the requirements of that habitat impact many other species living there. Most umbrella species are migratory , and their range may include different habitat types. The identification of an umbrella species can be an important aspect of conservation. The minimum species range of an umbrella species is often the basis for establishing the size of a protected area. The species range includes heavily forested ecosystems in both temperate and boreal subarctic biomes.

Corals are a key example of a foundation species across many islands in the South Pacific Ocean. These tiny animals grow as a colony of thousands and even millions of individual polyps. The rocky exoskeletons of these polyps create enormous structures around islands: coral reefs. Coral reefs are one of the most vibrant and biologically diverse ecosystems on the planet. Microscopic plankton , as well as crustaceans, mollusks, sponges, fish, and marine reptiles and mammals, are all part of healthy coral reef ecosystems.

Coral reef ecosystems also contribute to the human geography of a region. Pummeled by waves and ocean currents, coral exoskeletons can experience bioerosion. These eroded fragments of coral along with bony fragments of organisms such as foraminifera , mollusks, and crustaceans create a soft sand known as coral sand.

Coral sand beaches are among the most popular tourist destinations in the world. Like foundation species, ecosystem engineers contribute to the physical geography of their habitat.

Ecosystem engineers modify , create, and maintain habitats. Ecosystem engineers modify their habitats through their own biology or by physically changing biotic and abiotic factors in the environment. Autogenic engineers modify their environment by modifying their own biology. Corals and trees are autogenic engineers.

As they grow, they are a living part of the environment, providing food and shelter to other organisms. The hard exoskeletons left as corals die, continue to define and modify the ecosystem. Allogenic engineers physically change their environment from one state to another. Beavers are a classic example of allogenic engineers. Beavers help maintain woodland ecosystems by thinning out older trees and allowing young saplings to grow.

Converting these trees into timber for dams radically alters woodland meadows and streams, changing them into wetland habitats. Invasive species are often ecosystem engineers.

Lacking natural predators or abiotic factors to constrain them, these introduced species modify the existing environment in ways that inhibit the growth of the indigenous ecosystem. Kudzu regularly outcompetes native species for space and nutrients. As it crowds out native species, kudzu limits the pollinators, insects, and bird species that inhabit an area. An indicator species describes an organism that is very sensitive to environmental changes in its ecosystem. Indicator species are almost immediately affected by changes to the ecosystem and can give early warning that a habitat is suffering.

Changes associated with external influences such as water pollution , air pollution , or climate change first appear in indicator species. Oysters and other bivalves are filter feeders, meaning they filter water as they strain it for food particles. Oysters filter nutrients, sediments, and pollutants that enter the bay through natural or anthropogenic sources.

Oyster beds help protect fisheries, coastal habitats, and even benthic ecosystems. The health of oyster populations in the Chesapeake, therefore, is used to indicate the health of the entire ecosystem. A flagship species acts as a symbol for an environmental habitat, movement, campaign, or issue. They can be mascots for entire ecosystems. The identification of a flagship species relies heavily on the social , cultural, and economic value of a species. Flagship species may or may not be keystone or indicator species.

Flagship species can sometimes be symbols of general ideas about conservation, not representatives of specific ecosystems. However, specific issues are often associated with a specific animal. Residing in the grasslands of central and western North America, prairie dogs are a keystone species that supports some plus other species.

In addition to serving as a food source for coyotes, eagles, the endangered black-footed ferret , and other animals, they are ecosystem engineers, maintaining the health of arid grasslands by churning, aerating, and fertilizing soil as they create vast and intricate underground colonies.

Their digging allows an array of vegetation to thrive, which in turn supports a greater number of elk, bison, and other grazers. And their burrows provide shelter for animals like rattlesnakes, burrowing owls, and jackrabbits. When prairie dogs disappear from their native grasslands habitat, woody plants can take over , fundamentally altering the prairie ecosystem. Not only do they pollinate fruits, vegetables, and other crops that provide humans with everything from food to clothing to fuel , but they also help produce the seeds, nuts, berries, and fruit that countless other species in ecosystems around the world survive on.

Without bees, there would be a bottom-up cascade of consequences throughout the food chain. Despite this, bees like the endangered rusty patched bumblebee have failed to receive crucial protections in the United States. Left: Krill. At the top of the food chain, sharks are keystone predators that have a top-down impact on marine ecosystems worldwide.

By preying on the sickest, weakest, and slowest animals, they control the spread of disease and keep prey populations in check. They impact local habitat, too: By hunting predatory fish like grouper in Caribbean reef ecosystems, for example, sharks allow populations of herbivorous fish farther down the food chain to thrive, and these fish, in turn, graze on algae that otherwise degrade coral reef.

Some types of corals are considered keystone species as well. One example is ivory tree coral , which is found in the waters off the southeastern United States, the Gulf of Mexico, and the Caribbean and provides valuable habitat for more than invertebrates.

Other oceanic keystone species include krill a vital food source for myriad whales, seals, and seabirds in Antarctica and mangrove-dwelling crabs which manage leaf litter and create burrows that improve underwater soil health. Native to the Sonoran Desert of the southwestern United States and northwestern Mexico, the saguaro cactus is a keystone species that provides critical nesting spots for birds like red-tailed hawks and woodpeckers the latter of which peck new nest holes each year, leaving old holes for other birds.

These cacti serve as an important source of sustenance, too. Their blooming flowers feed bats, birds, and bees, while their fruit, which ripens when the desert is at its driest, is often the sole wet food source for myriad mammals, insects, and other species.

Other desert keystone species include the desert tortoise of the Mojave which digs burrows that other animals rely on for protection from predators and the desert heat and the Australian dingo, which preys on both predators in the middle of the food chain, like invasive red foxes and feral cats, as well as a wide range of herbivores e.

In the Canadian boreal , the snowshoe hare is an example of a keystone prey species, serving as food for the threatened Canada lynx which relies on snowshoe hares for more than 75 percent of its winter diet , and other predators. In the boreal, keystone species also include trees like aspen and willow these provide critical habitat for myriad organisms like lichens, fungi, insects, and birds and plants like wild red raspberries, which are a critical food resource for animals from bees to bears.

Cold, treeless, and typically snowy, the Arctic tundra encompasses the northern part of the Northern Hemisphere and is an ecosystem in which few plant and animal species thrive.

One of its most vital prey species is the lemming, a small rodent that undergoes large, cyclic population fluctuations that impact the whole tundra food web. A keystone species, lemmings feed predators like arctic foxes, snowy owls, and weasels; as hungry herbivores, they also impact the prevalence, health, and composition of the vegetation they feed on. Meanwhile, on a series of islands between Norway and the North Pole, dovekies are keystone birds that provide crucial compost for local vegetation while supporting polar bears and arctic foxes as prey.

In tropical forests around the world, fig trees serve as a keystone resource, bearing fruit that feeds more than 1, types of birds, bats, and other species year-round including, critically, times of the year when other food resources are scarce.

Some seed dispersers—animals that move through the forest, leaving droppings filled with seeds that can then take root and grow—are also considered keystone species. Members of the veterans community traveled to Washington, D. You may have never heard of them, but there are hundreds around the world. Find out what makes this specific type of reserve so special. Protecting these nine species will help save the region's iconic sagebrush prairies, grasslands, and mountains.

Why our success in saving the greater sage grouse is key to preserving millions of acres of habitat and hundreds of other species across the American West. Keystone Species By: Stephen C. Wagner Department of Biology, Stephen F. Citation: Wagner, S. Nature Education Knowledge 3 10 A keystone in an arch's crown secures the other stones in place.

Keystone species play the same role in many ecological communities by maintaining the structure and integrity of the community. Aa Aa Aa. Paine's Milestones. Figure 1: Food web of species present in temperate intertidal ecosystem. Figure 2: Effect of removal of top predator on total species number in intertidal ecosystem. Other Keystone Species. Figure 3: A dam built by beavers as keystone modifiers.

Figure 6: Map of wolf pack territories in Yellowstone National Park in Public Domain National Park Service. References and Recommended Reading Baril, L. Grooms, S. Return of the Wolf. Minocqua, WI: Northword Press, Internal Memorandum. Yellowstone National Park, Garrott et al. Article History Close. Share Cancel. Revoke Cancel. Keywords Keywords for this Article.

Save Cancel. Flag Inappropriate The Content is: Objectionable. Flag Content Cancel. Email your Friend. Submit Cancel. This content is currently under construction. Explore This Subject. Topic rooms within Community Ecology Close. No topic rooms are there. Or Browse Visually. Other Topic Rooms Ecology. Student Voices. Creature Cast.

Simply Science. Green Screen. Green Science. Bio 2. The Success Code. Why Science Matters. The Beyond. Plant ChemCast. Postcards from the Universe. Brain Metrics. Mind Read. Eyes on Environment. Accumulating Glitches. Saltwater Science. Microbe Matters. You have authorized LearnCasting of your reading list in Scitable. Do you want to LearnCast this session? This article has been posted to your Facebook page via Scitable LearnCast. Change LearnCast Settings.