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Topic: Keystone species

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	Keystone species - Wikipedia, the free encyclopedia
		A keystone species is a species that has a disproportionate effect on its environment relative to its abundance.
		A classic keystone species is a small predator that prevents a particular herbivorous species from decimating a dominant plant species.
		Another ecosystem engineering keystone species is the beaver, which transforms its territory from a stream to a pond or swamp.
	en.wikipedia.org /wiki/Keystone_species (694 words)

	BookRags: Keystone Species Summary
		This means that if this species propagates or dies off in large numbers, the relative population sizes of other species in the community will be skewed, but the community will eventually return to its original state.
		Note that the keystone species is not the dominant species—it does not have the largest number of individuals in the ecosystem.
		Because species diversity is a strong signifier for a healthy habitat, it is important for humans to understand how to preserve the greatest species diversity within remaining natural habitats.
	www.bookrags.com /research/keystone-species-ansc-03 (1120 words)

	Keystone Species Hypothesis
		The research resulting in the keystone species concept was done on Makah Tribal lands on the outer coast of Washington State, with the Makahs' permission.
		Keystone species are usually noticed when they are removed or they disappear from an ecosystem, resulting in dramatic changes to the rest of the community.
		A good illustration of Paine's keystone species concept is provided by the sea otter, which formerly occupied a range extending from the northern Japanese archipelago, through the Aleutian Islands, down the coast of North America as far south as Baja California.
	www.washington.edu /research/pathbreakers/1969g.html (693 words)

	Bagheera: An Endangered Species and Endangered Animal Online Education Resource
		A keystone species is a species on which the persistence of a large number of other species in the ecosystem depends.
		Keystone species may be top carnivores that keep prey in check, large herbivores that shape the habitat in which other species live, important plants that support particular insect species that are prey for birds, bats that disperse the seeds of plants, and many other types of organisms.
		Keystone species may occur at any level of the ecosystem, from plants and herbivores (plant eaters), to carnivores (meat eaters), and detritivores (waste eaters).
	www.bagheera.com /inthewild/spot_spkey.htm (335 words)

	Biodiversity Loss: cascade effects
		When the keystone predator Pisaster ochraceus (a starfish) is removed from the intertidal zone in the Pacific northwest of the United States, the intertidal community changes from one with a high diversity of relatively large bottom-dwelling invertebrates to a virtual monoculture of the starfish's favorite prey--the mussel (Mytelus edulis).
		By increasing the abundance of the keystone mutualists for instance, it might be possible to increase populations of dependent species.
		Populations of such species, including carnivores, tend to be limited by the amount of prey available, whereas species low in the food chain, such as herbivores, are more often limited by their predators or pathogens.
	pubs.wri.org /pubs_content_text.cfm?ContentID=575 (1171 words)

	Keystone species and how they relate to the aquarium trade.
		While the precise definition of keystone species is a matter of controversy amongst ecologists, we feel that these debates over definitions are not as important as simply accepting the fact that there are species whose very existence influences and even controls the existence of more than one other species.
		Identification of keystone fish species is also often determined through an observation of dramatic rises or falls in populations of plankton and other invertebrates that represent the food of these fish.
		For example, the depletion of certain food species such as some flatfish and haddock may very well have caused an over-population of their prey, particular sea star species such as the Crown of Thorns, that in turn are now decimating shellfish such as scallops, and many reefs.
	www.aquariumpros.com /articles/keystone.shtml (996 words)

	Conservation Ecology: Linking keystone species and functional groups: a new operational definition of the keystone ... (Site not responding. Last check: 2007-10-23)
		A keystone species is held to be a strongly interacting species whose top-down effect on species diversity and competition is large relative to its biomass dominance within a functional group.
		The ecological term "keystone species" was coined by Paine (1969a), and subsequently defined (Paine 1969b:950) as a species of high trophic status whose activities exert a disproportionate influence on the pattern of species diversity in a community.
		However, those species to be identified and removed a priori must, by definition, have a low biomass in relation to the community as a whole, thus forcing the researcher to search for potential KS within the veiled reality of the miniscule among the tremendous biodiversity of nature.
	sunsite.wits.ac.za /eco/vol7/iss1/resp11/main.html (5206 words)

	Keystone Species - Essential to Ecosystems and Biodiversity (Environmental Article) (Site not responding. Last check: 2007-10-23)
		In any event, just as the keystone is essential to the physical integrity of a stone arch, a keystone species is defined as one that has a critical role in determining and maintaining the overall relationship of plants and animals within an ecosystem.
		Other examples of keystone species are the prairie dog in the US Southwest, the banner-tailed kangaroo rat in the Chihuahuan Desert grassland (also in the Southwest), and the red-naped sapsucker in Colorado.
		But not all keystone species are cute and furry or feathered: Certain species of truffles are thought to be keystone fungal species, and oysters and other shellfish are considered keystone species in a variety of estuarine ecosystems.
	www.grinningplanet.com /2004/06-22/keystone-species-article.htm (975 words)

	Ecological Value (Site not responding. Last check: 2007-10-23)
		Species that are important due to their sheer numbers are often called dominant species.
		Species that have important ecological roles that are greater than one would expect based on their abundance are called keystone species.
		The impact of removing an individual or several keystone species from kelp forests in the Pacific is examined in example 1.
	cnx.org /content/m12154/latest (712 words)

	Indicator species - Wikipedia, the free encyclopedia
		Indicator species are unique environmental indicators as they offer a signal of the biological condition in a watershed or ecosystem, and are a warning system that pollution has entered the food web.
		They can be abundant or dominant in the community, and occasionally can be a keystone species.
		The term indicator species is a bit misleading, as indicators are often whole groups of flora/fauna types which can be used to assess environmental condition.
	en.wikipedia.org /wiki/Indicator_species (114 words)

	Austin Biodiversity Project - Species (Site not responding. Last check: 2007-10-23)
		Species come in all shapes and sizes, from the tiny organisms that we can see through a microscope to huge redwood trees.
		What we do know is that certain species, called keystone species, play critical roles in the ecosystems they inhabit because they affect the abundance and health of many other species.
		Examples of keystone species include brown algae, commonly known as kelp, in Pacific coastal ecosystems, fruit-eating bats in southwestern deserts, and corals in tropical coastal waters.
	www.cs.utexas.edu /users/s2s/pending/biodiversity3/src/species.html (217 words)

	Conservation Ecology: Determining keystone species (Site not responding. Last check: 2007-10-23)
		Turnover cycles of energy and matter are dominated by the life activities of keystone species, and these activities determine the major shifts at the spatial and temporal scales at which these species exist.
		Population mosaics of key species have largest spatial-temporal dimensions, and population mosaics of subordinate species are thereby determined by key-species." The last means that vegetation patterns produced by key species are larger and last longer than those produced by subordinate species.
		It needs to be underlined that we propose to name as keystone species only those species whose populations (or flocks of animals, as rule) either support or essentially alter the main vegetation pattern of the ecosystem.
	sunsite.wits.ac.za /eco/vol2/iss2/resp2 (635 words)

	Ecorisk Fundamentals: 1.6 Indicator and Keystone Species (Site not responding. Last check: 2007-10-23)
		An indicator species is a species that has such a narrow range of ecological tolerance that their presence or absence is a good indication of environmental conditions.
		Some species are known to have a disproportionately large role in determining the overall community structure within an ecosystem.
		The role of keystone species is not clearly understood until removal of the species, either artificially or by natural means, has occurred.
	web.ead.anl.gov /ecorisk/fundamentals/html/ch1/1.6.htm (420 words)

	WWF - Global Species Programe: how WWF classifies species (Site not responding. Last check: 2007-10-23)
		Flagship species may or may not be keystone species and may or may not be good indicators of biological process.
		For WWF, a “priority species” may be either a flagship or a keystone species and is chosen to represent an ecoregion or region.
		An indicator species is a species or group of species chosen as an indicator of, or proxy for, the state of an ecosystem or of a certain process within that ecosystem.
	www.panda.org /about_wwf/what_we_do/species/our_solutions/flagship_keystone_indicator_definition.cfm (405 words)

	Cottonwood Ecology Keystone Species
		A keystone species is defined as a species that has a disproportionate impact on the community relative to its abundance (Paine 1966, Power et al.
		We propose that plant genetic traits determine the distributions of keystone species, which in turn affect the distributions of hundreds of other species.
		Because plant genetic traits (e.g., defensive chemistry) can influence the distribution of keystone herbivores, which in turn affect many other species, it is important to understand how genetic variation in plants influences the abundance, distribution, and stability of keystone species.
	herb.bio.nau.edu /poplar/keystone.htm (211 words)

	Keystone Species
		A keystone species is 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.
		Keystone species help to support the ecosystem (entire community of life) of which they are a part.
		Black-Tailed Prairie Dogs Are a Keystone Species of the Prairie Ecosystem.
	www.prairiedogs.org /keystone.html (304 words)

	Keystone species
		A keystone species is one whose impact on its community or ecosystem is disproportionately large relative to its abundance [
		Although the idea of keystone species is intuitively appealing, it has been much criticized in the ecological literature.
		In spite of its limitations, the keystone species concept has some usefulness in the same way that elasticity coefficients in a Leslie or Lefkovitch matrix are useful.
	darwin.eeb.uconn.edu /eeb310/lecture-notes/interactions/node2.html (925 words)

	Aspen: A Keystone Species
		In many tree species, new bark cells grow beneath the old layer of dead cells which, as the trunk expands, splits apart to form furrows and wrinkles, as in firs or cottonwoods.
		The modern species is probably a hybrid of its two ancient ancestors.
		Most species in a given ecosystem owe their existence to the myriad connections to other species, none overly abundant but together creating a functional whole, an interdependent community able to meet the needs of all its inhabitants.
	www.amnh.org /nationalcenter/youngnaturalistawards/1998/aspen.html (2968 words)

	Field Trip Earth: Elephants as Keystone Species
		The keystone's disappearance triggers the loss of other resident species, and the intricate connections among the remaining residents begin to unravel.
		Elephants appear to be keystone species in African grasslands.
		As keystone species, elephants stop the progression of grassland to forest or thicket by by weeding out the trees and shrubs.
	www.fieldtripearth.org /article.xml?id=754 (1219 words)

	Conservation Ecology: Herbivores as keystone predators
		Paine (1969) not only coined the term “keystone species,” but also presented the characteristics required for a species to be given keystone status: (1) it provides top-down effects (such as predation) on lower trophic levels, and (2) it prevents the monopolization of a critical resource (such as competition for space) in lower trophic levels.
		However, whether or not the hare is also a keystone species must await the results of its experimental removal to determine if such a removal regulates competitive interactions, and species diversity, within the plant functional group that it eats.
		In summary, herbivores are predators of plant species and snowshoe hare may be a keystone species if it regulates competitive interactions within the functional group of its prey, but not because it is prey for top carnivores.
	www.ecologyandsociety.org /vol6/iss2/resp8 (489 words)

	Coastlines 2004-2005: Spotlight on Eelgrass A Species and Habitat at Risk
		Darwin explained that the abundance of every species is influenced by that of other species, which serve as its food, create its habitat, and/or influence it through a web of relationships.
		Populations of species dependent on eelgrass, as well as those indirectly associated with eelgrass, were substantially reduced.
		Bay scallops and mussels are examples of species whose habitat, at least for a time during their lifecycle, is a blade of eelgrass.
	www.mass.gov /czm/coastlines/2004-2005/habitat/e_grass.htm (1947 words)

	Keystone species - Search Results - MSN Encarta
		Species and Speciation, basic concepts in the classification of organisms.
		In simple terms, a single species is a distinct kind of organism, with a...
		Evolution, in biology, complex process by which the characteristics of living organisms change over many generations as traits are passed from one...
	encarta.msn.com /encnet/refpages/search.aspx?q=Keystone+species (116 words)

	KeystoneProtect (Site not responding. Last check: 2007-10-23)
		It aims to educate inspire and spread awareness about the species and their current situation and actions being implemented to help save these animals and it’s environment.
		Keystone Species are considered as important biodiversity indicators used in the assessment of the ecological integrity of various ecosystems in the Philippines and elsewhere.
		Learn about keystone species, it’s importance to the ecosystem and the animals that are classified as a keystone species.
	www.keystoneprotect.com (182 words)

	MediaRights: Film: Natural Connections (Series): Keystone Species (Site not responding. Last check: 2007-10-23)
		His experiment on the connection between starfish and mussels has resulted in one of the most important principles of modern ecology, known as "keystone species".
		Paine showed that certain species are critically important to the balance of particular ecosystems.
		The loss of a keystone species can have a devastating impact on that ecosystem's biodiversity.
	www.mediarights.org /film/natural_connections_series_keystone_species (110 words)

	Cottonwood IRCEB Grant
		species have dramatic effects on communities, the strongest effects of plant genetic diversity for community structure may occur through influences on keystone species.
		Last, markers that do not cross species boundaries are probably associated with negative genes, while those that introgress far into the narrowleaf zone may be associated with traits that increase fitness and are under positive selection.
		Based upon reproduction success, the fossil record, and a hybrid speciation event, hybrid cottonwoods are at least equal in fitness to their parental species.
	herb.bio.nau.edu /poplar/nsf.htm (1881 words)

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