What Is Meant By Keystone Species?

Some species are essential to the survival of the other species in the ecosystem, typically in every environment. A large predator or a little plant could be the keystone species, without them the ecosystem might not exist. Any arrangement or community's "keystone" is regarded as one of its most important components. A keystone species is an animal that keeps the fabric of an ecosystem—marine or otherwise—together. 

 

Ecosystems would seem extremely different without their keystone species. If a keystone species vanished, some ecosystems might not be able to adjust to environmental changes. That might lead to the ecosystem's demise or might let an invading species take control and drastically change the ecosystem's course.

 

Since a keystone species is not a formal designation, scientists may debate which plants or animals in a particular ecosystem deserve the title, and the concept, according to some wildlife experts, oversimplifies the function of one animal or plant in intricate food webs and environments. However, referring to a certain plant or animal as a keystone species can assist the general public, appreciate how crucial one species can be to the existence of many others? 

 

Many scientists mention three categories of keystone species: predators, ecosystem engineers, and mutualists.

•    Predators aid in the management of prey species' numbers, which has an impact on the number of plants and animals farther up the food chain. For instance, sharks frequently eat sick or old fish, allowing healthier species to flourish. Sharks are able to prevent smaller creatures from overgrazing and eradicating sea grass beds only by being present near those areas. 

 

•    Sea turtles are one of tiger sharks' favorite prey, and scientists in Australia noticed that when they weren't nearby the grass beds, sea turtles had a tendency to decimate them. However, the sea turtles were compelled to graze over a much wider area when tiger sharks began patrolling the grass beds. 

 

•    An organism that alters, destroys, or creates new habitats is known as an ecosystem engineer. The beaver is likely the best illustration of a keystone engineer. Beavers cut down old or dead trees along riverbanks to utilize building their dams, which is essential to the health of river ecosystems. This enables an abundance of new, healthier trees to sprout. River water is diverted by the dams, resulting in wetlands where a variety of animals and plants can flourish.

 

•    Mutualists are two or more species that cooperate with one another for the benefit of the ecosystem as a whole. One of the best examples of this are bees. In addition to collecting nectar from flowers, bees also transport pollen from one flower to the next, increasing the likelihood of fertilization and promoting more flower growth. The main food sources for bees themselves are nectar and pollen.

 

Other keystone species groups are recognized by some scientists. Predators, herbivores, and mutualists are on additional list. Another lists resource competitors, mutualists, and predators.

Plants can be considered keystone species. For example, mangrove trees play a crucial function in stabilizing shorelines and preventing erosion along numerous coastlines. Their roots, which extend down through the shallow water, also offer a haven and a feeding area for small fish. Often, it takes the extinction of a keystone species for the importance of that species in an ecosystem to be fully understood. 

 

Robert Paine, an ecologist who popularized the phrase "keystone species" in the 1960s, discovered the significance of such species while researching starfish along Washington State’s rugged Pacific coast. Because the starfish consumed mussels, the population of mussels was kept under check, allowing many other species to flourish. As part of an experiment, the starfish were taken out of the area, which caused the mussel population to explode and drive out other species. 

 

The ecosystem's biodiversity was severely diminished. According to Payne's research, finding and safeguarding keystone species can assist in maintaining the population of numerous other species. 

 

•    An ecosystem's keystone species contributes to define an entire ecosystem. Without its keystone species, the ecosystem would either no longer exist or would change significantly. A species that plays a vital role in defining an ecosystem is known as a keystone species. Without its keystone species, the ecosystem would either no longer exist or would change significantly.

 

•    There is low functional redundancy in keystone species. This means that no other species would be able to fill the species' ecological niche if it were to vanish from the ecosystem. The ecosystem would be forced to undergo a significant change, allowing for the influx of new, potentially invasive species. 

 

•    A keystone species can be any type of organism, including fungi and plants, they are not usually the biggest or most numerous species in an ecosystem. Animals that have a significant impact on food webs are, nevertheless, virtually universally used as examples of keystone species. The impact these creatures have on food webs varies depending on the habitat, such as: mutualists, herbivores, and carnivores.

 

•    Although not always, a keystone species is a predator. The distribution and population of numerous prey species can be managed by a small number of predators. Research on the impact of a marine predator on its habitat served as the basis for the entire keystone species concept. The removal of a single species, the Pisaster ochraceus sea star, from a tidal plain on Tatoosh Island in the U.S. state of Washington has a profound impact on the ecology, according to research by American zoology professor Robert T. Paine. 

 

•    On Tatoosh Island, purple sea stars, also known as Pisaster ochraceus, are a significant barnacle and mussel predator. After the sea stars disappeared, mussels moved in and displaced other species, such as the benthic algae that supported communities of sea snails, limpets, and bivalves. The tidal plain's biodiversity was reduced in half within a year due to the lack of a keystone species. 

 

•    The existence of grey wolves in the Greater Yellowstone Ecosystem is another illustration of a predator operating as a keystone species. The Montana, Wyoming, and Idaho state borders are shared by the Greater Yellowstone Habitat (GYE), a vast and diversified temperate ecosystem. The GYE comprises freshwater habitats, mountains, forests, meadows, and active geothermal basins.

 

•    The presence of wolves in the Greater Yellowstone Ecosystem at least partially regulates the elk, bison, rabbit, and bird species. These prey species' feeding habits and the locations of their burrows and nests are mostly a response to wolf activity. Additionally, scavenger animals like vultures are under the power of wolf activities. Hundreds of wolves were roaming the GYE when the U.S. government set aside area for Yellowstone National Park in the late 19th century. 

 

•    They prayed largely on large herds of elk and bison. Governments at the municipal, state, and federal levels tried to eliminate wolves from the GYE out of concern for the effect they would have on those herds as well as local cattle. In 1924, the last wolf pups in Yellowstone were exterminated.

 

•    This started a top-down trophic cascade in the Greater Yellowstone Ecosystem. A trophic cascade describes changes in an ecosystem due to the addition or removal of a predator. A top-down trophic cascade outlines the changes that happen when the top predator in an ecosystem is gone. (A bottom-up trophic cascade depicts the evolution that happens when a producer or primary consumer is eliminated.)

 

•    Elk populations in Yellowstone exploded due to the absence of an apex predator. Because of the competition between elk herds for food sources, grasses, sedges, and reeds did not have enough time or space to thrive. Other species' populations, including those of fish, beavers, and songbirds, were impacted by overgrazing. For survival, these creatures are dependent on plants and the roots, flowers, timber, and seeds they produce.

 

•    The absence of wolves and the ensuing elk overgrazing had an impact on the physical topography of the Greater Yellowstone Ecosystem. Wetland plants failed to attach precious soil and sediments, causing stream banks to erode. The lack of shade provided by trees and bushes led to an increase in lake and river temperatures. 

 

•    The United States government started returning wolves to the Greater Yellowstone Ecosystem in the 1990s. The outcomes are noteworthy. The number of elk has decreased, willow heights have grown, and songbird and beaver populations have rebounded.

 

•    Keystone species can also include herbivores. Their consumption of plants aids in maintaining an ecosystem's biological and physical components. Elephants are a keystone species in African savannas, such as the Serengeti plains in Tanzania. Elephants consume savanna-grown shrubs and tiny trees like acacia. Elephants can topple and uproot acacia trees, even if they reach a height of one meter or higher. 

 

•    The savanna remains a grassland and not a forest or woodland due to this feeding behavior. With Elephant population is in control it allows grasslands to flourish and support grazing species like antelope, wildebeests, and zebras. The warm, dry soil of a savanna is ideal for burrowing by smaller animals like mice and shrews. The savanna serves as a major source of food for predators like lions and hyenas.

 

•    Two or more species that interact in a mutually advantageous way are said to be keystone mutualists. A change in one species would have an effect on the other, changing the ecosystem as a whole. Pollinators, such as bees, are frequently keystone mutualists. Pollinators frequently keep gene flow and dispersal throughout large-scale ecosystems. An indigenous plant species and a species of hummingbird work together as keystone mutualists in the wooded grasslands of Patagonia (near the southernmost point of South America). 

 

•    Local trees, shrubs, and flowering plants have developed to rely only on the green-backed fire crown hummingbird ‘’Sephanoides sephanoides’’ for pollination. 20% of the area plant species are pollinated by green-backed firecrowns. The sugary nectar that makes up the majority of the hummingbird's diet is then produced by these plants. Without green-backed firecrowns, portions of the current Patagonian habitat would vanish because no other pollinator has developed the ability to pollinate these plants, reducing their functional redundancy to almost zero.

 

There are other types of organisms that are equally important to the survival of their ecosystems as keystone species. 

 

•    Keystone species and umbrella species are frequently confused. Both names refer to a single species that supports numerous additional species. The significance of an umbrella species is linked to its geographic species range, which is the main distinction between umbrella species and keystone species.

 

•    Because of their extensive habitat needs, umbrella species have an impact on many other species that live there. The majority of umbrella species migrate, and they may use a variety of habitats in their range. An essential component of conservation may be the identification of an umbrella species. The size of a protected area is frequently determined using the minimum species range of an umbrella species.

 

•    An umbrella species with a range of more than 1,000 kilometers (620 miles) in Russia's far east, including parts of China and North Korea, is ‘’the Siberian tiger’’, an endangered species. The species range spans both temperate and boreal (subarctic) biomes, and includes densely wooded environments. The Siberian tiger range's snowy "umbrella" covers populations of deer, boar, and moose.

 

•    A habitat can be created or maintained in large part by foundation species. A prime example of a foundation species present on numerous islands in the South Pacific Ocean are corals. These tiny creatures develop into colonies made up of tens of thousands or perhaps millions of distinct polyps. These polyps' rocky exoskeletons give rise to coral reefs, which are vast structures ringing islands.

 

•    One of the planet's most dynamic and biologically varied ecosystems is the coral reef. Healthy coral reef ecosystems include microscopic plankton as well as crustaceans, mollusks, sponges, fish, and marine reptiles and mammals.

 

•    Coral reef ecosystems play a role in a region's human geography as well. Coral exoskeletons may erode due to exposure to waves and ocean currents. These degraded coral fragments, coupled with the bone remains of other animals including foraminifera, mollusks, and crustaceans, result in coral sand, a soft sand. One of the most well-liked tourist spots worldwide is coral sand beaches.

 

•    Ecosystem engineers, like foundation species, influence the physical topography of their habitat. Habitats are altered, created, and maintained by ecosystem engineers.

 

•    By modifying biotic and abiotic elements in the environment physically or through their own biology, ecosystem engineers can alter their habitats. Autogenic engineers alter their surroundings by altering their biological makeup. Trees and corals are self-replicating engineers. 

 

•    They become a living component of the environment as they develop, giving other organisms food and a place to live. The environment is still being defined and altered by the hard exoskeletons that remain after corals die.

 

•    Engineers with allogenic environments alter their surroundings physically. A prime example of an allogenic engineer is the beaver. By removing older trees and promoting the growth of young saplings, beavers contribute to the preservation of woodland ecosystems. Wooded meadows and streams are drastically altered when these trees are harvested for dam construction, becoming wetland habitats. Ecosystem engineers are frequently invasive species. 

 

•    Because they lack abiotic or natural predators to keep them in check, these introduced species alter the environment in ways that stunt the development of the native ecosystem.

 

•    The so-called "vine that ate the South," kudzu, is an invasive plant species that changed the southeastern United States' ecosystem. For space and resources, kudzu consistently outcompetes natural plants. Kudzu restricts the variety of pollinators, insects, and bird species that can live in a region by displacing native species.

 

•    An indicator species describes an organism that is very sensitive to environmental changes in its ecosystem. Indicator species are the first to exhibit changes brought on by external forces such as air pollution, water pollution, or climate change. Because of this, sentinel species are another name for indicator species.

 

•    Oysters are an indicator species in the Chesapeake Bay, the "nation's estuary." 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. Fisheries, coastal habitats, and even benthic ecosystems are all aided by oyster beds. 

 

•    Therefore, the health of the oyster populations in the Chesapeake is used to gauge the overall health of the ecosystem. 

 

•    A flagship species serves as a representative of a certain environmental habitat, movement, cause, or problem. They may serve as the mascots for entire ecologies.

 

•    The social, cultural, and economic worth of a species is a major factor in determining whether it should be considered a flagship species. Frequently, they are "charismatic mega fauna"—large animals that are popularly liked because of their size or cultural significance. 

 

•    Keystone or indicator species may or may not be flagship species. Flagship species aren't only the representatives of particular ecosystems, they can also serve as symbols for broader conservation concepts. However, particular problems are frequently linked to a particular animal. The young harp seal became the symbol of the campaign to ban seal hunting in the Arctic. The undisputed emblematic creature linked to climate change is the polar bear.

 

•    The giant panda is perhaps the most familiar flagship species. Pandas are the global symbol of endangered species and the value of captive breeding. 

 

Keystone hosts are frequently referred to as plants and other providers who give food and shelter for keystone species. A keystone host is kelp. For sea otters, kelp forests offer a stable home and nutrient-rich food for their prey, like fish and sea urchins. 

 

Despite being preyed upon, keystone feast can maintain robust populations. Wildebeests, prey for predators from lions to crocodiles of the African savanna, are an example of keystone prey.

 

Although not always apex predators, keystone species are frequently predators. They are typically secondary consumers instead. Despite being ferocious predators of barnacles and mussels, for instance, sea stars are a prey species for fish and sea anemones. 

 

It's possible for keystone species to act as "nutrient vectors" by moving nutrients from one habitat to another. For instance, Grizzly bears feed on salmon. Salmon carcasses can be dumped miles away from rivers and streams. Decomposing salmon carcasses release nutrients into the soil that may not be present in nearby terrestrial ecosystems. 

 

Keystone species were first described by zoologist Robert T. Paine, who also had an unconventional approach to his job. Paine experimented by actively altering the habitat of the Pisaster ochraceus sea star rather than merely monitoring it. 

 

To find out what occurred when the sea stars were gone, Paine and his University of Washington students spent 25 years removing them from a tidal area on the shore of Tatoosh Island, Washington. He was one of the pioneering researchers in his field to conduct this kind of experimentation in nature.