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Keystone species and Ecosystem In a population and ecosystem, describe/define the role that a keystone species plays. Hi, I hope that the following will help you understand and be able to formulate your answer to this problem. Divide the word up in to two parts and it will give you an idea as to the importance of this concept, crucial in today’s rapidly changing and evolving environment with rapid depletion of resources, climate change and rise in global pollution. The word key can be used to mean central, important, vital. The word stone is often used in terms of it’s signifiance e.g. foundation stone, tomb stone etc. Combine the words together had been done in terms of architecture and the concept can be a valuable one. I have included the definition from Wikipedia As follows: 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 analagous 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. Similarly, an ecosystem may experience a dramatic shift if a keystone species is removed, even though that species was a small part of the ecosystem by measures of biomass or productivity. It has become a very popular concept in conservation biology. An important point to stress would be that the species considered to be the keystone in an ecological niche would not necessarily be the top carnivore or the main producer etc, but the important feature is that there removal has drastic consequences with the possible collapse of the ecological niche or alternatively a drastic and dramatic effect on the extent of the biodiversity. Where this impinges on human resources particularly in developing countries that effects can similarly be dramatic for human societies. It is important to note that it may be an oversimplification of living communities (or ecosystems), in which all species playsome role. It is also not possible to identify keystone species in every ecosystem. However the idea illustrates powerfully how the loss of a species from an ecosystem (or the addition of a species that does not “belong” in that ecosystem) can have a profound effect on how thatecosystem works, often to the detriment of humans. The keystone species is often the “top predator” in food webs, and so it is not surprising thatit has a profound effect on the balance of numbers in species at lower levels in the webs. There are good Scottish examples to illustrate this process. For example, the extermination of the wolf in the late eighteenth century removed the last predator of red deer. Today – helped by the way we manage the land and by inadequate culling policies – red deer have increased to huge numbers in many parts of the Highlands, causing problems for farmers, crofters, grouse-moorowners and for the conservation of our native forests and plant communities.If one species becomes extinct, this can have a knock-on effect on others it interacts with. Indeed, an analysis has suggested that the number of species globally threatened with extinction is nearly 50 per cent higher than the number currently listed as endangered. This is because the survival of 6,300 non-threatened species depends on the existence of threatened species. In other words Some species are — by virtue of their interactions with others — important to the continued existence of their ecosystems. These are known as 'keystone' species. The extinction of a keystone species is predicted to cause a cascade of further extinctions. In conservation biology, keystone species are ones which play a central, critical role in ecosystems, and upon which many other species depend. If an ecosystem can be returned to a state in which the keystone species flourish, then all the other species which depend on it will benefit as well. In the boreal component of the Caledonian Forest, such as the pinewoods in Glen Affric, the Scots pine is a keystone species. Therefore, by concentrating our efforts on Scots pines, we find that the whole forest community begins to recover. Another example of a keystone species, for riparian (or river-side) ecosystems is the European beaver , which through its dam-building creates micro-habitats of still water. These benefit certain fish species and promote the growth of aquatic vegetation, which in turn provides food for mammals such as the moose. Some other examples that you will find in the literature include: Limpets as keystone species of rocky shores because they keep algal levels in check. They are not considered to be endangered. The removal of starfish in certain ecological niches has been responsible for collapse of some marine habitats In his book,The Diversity of Life (Harvard University Press, 1992), Wilson illustrated the idea with reference to the Californian sea otter, which was hunted almost to extinction for its valuable pelt. Sea otters (Enhydra lutris) were once found along the entire Pacific coast of North America, but are now confined to California and Alaska. They were huntedfor their valuable fur, and the Californian population was thought to be extinct until a small group was discovered on a remote coast in 1938. With careful protection, numbers have built up to over 2,000 along one stretch of the Californian coast. Wilson wrote:– “In places where sea otters disappeared completely, an unexpected sequence of events unfolded. Sea urchins, normally among the major prey of the otters, exploded in numbers and proceeded to consume large portions of the kelp and other inshore seaweeds. In otter times, the heavy kelp growth, anchored on the sea bottom and reaching to the surface, was a veritable forest. Now it was mostly gone, literally eaten away. Large stretches of the shallow ocean floor were reduced to a desert-like terrain, called the sea urchin barrens.” In these sea urchin barrens, few fish could live and, as a result, many inshore fishermen went out of business. The great fisheries and the coastal canneries of towns like Monterey virtually disappeared, just as the sea otter had done. The sea otter story illustrates how easily marine ecosystems are disrupted. We know least about how these ecosystems work, yet we continue to over-exploit individual species from the seas. There are already good examples of the complex impacts such exploitation may have. For example, overfishing of cod and other large predatory fish is thought to have led to an increase in numbers of the smaller fish on which they preyed. Some seabirds, such as the puffin, which feed on smaller fish, may have benefited initially from these changes, and this may explain recent increases in the size of some of their breeding colonies. Now, however, industrial fisheries increasingly are targeting smaller fish, like sprats and sand eels. We have seen the impact of such fisheries already on Norwegian islands such as Røst, where almost a million puffin chicks starved to death during several summers in the 1980s because their parents could not find enough food to feed them. CHECKSANDBALANCES . To quote Edward Wilson from his book The Diversity of Life (1992) “Because scientists have yet to put names on most kinds of organisms, and because they entertain only a vague notion of how ecosystems work, it is reckless to suppose that biodiversity can be diminished indefinitely without threatening humanity itself. . . . As extinction spreads, some of the lost forms prove to be keystone species and trigger a ripple effect through the demographies of the survivors. The loss of a keystone species is like a drill accidentally striking a power-line. It causes lights to go out all over.” CONSERVATION Useful websites http://www.snh.org.uk/pdfs/education/biodiversity/3%20keystone%20sp ecies.pdf http://www.treesforlife.org.uk/tfl.eco.html#3 www.abdn.ac.uk/biology/lectures/bi2001_foodwebs.ppt http://www.scidev.net/ms/biofacts/index.cfm?pageid=423 http://en.wikipedia.org/wiki/Keystone_species http://www.bbc.co.uk/nature/blueplanet/factfiles/molluscs/limpet_bg.sht ml http://www.pima.gov/cmo/sdcp/sdcp2/fsheets/key/key.html