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Opportunistic Species

Opportunistic Species In Novel Circumstances

Sometimes, species that are not particularly prominent in their native habitat become important pests when they are introduced by humans into a new habitat. In such cases, these organisms are opportunistically responding to a novel ecological circumstance that enhances their access to resources. This response is made possible because the species are no longer constrained by the specifically adapted herbivores, predators, or diseases that occur in their native habitat, a situation that is referred to as ecological release. Most of the important species of weeds in agriculture have opportunistically responded to favorable circumstances in the new environments to which they have been introduced, as have invasive animal pests, such as rats and mice.

Of course, there are limitations to the ecological success of opportunistic species. In stable environments, where disturbance is infrequent, there are few circumstances that are favorable to opportunistic species, and they will be rare in the biota. Such conditions are common, for example, in old-growth forests and other climax ecosystems. However, many human activities result in extensive disturbances of natural ecosystems. As a result, opportunistic species are faring much better today than they did prior to the global environmental changes that are being caused by humans.



Ambasht, R.S., and Navin K. Ambasht. Modern Trends in Applied Terrestrial Ecology. New York: Plenum, 2003.

Barbour, M.G., J. H. Burk, and W. D. Pitts. Terrestrial Plant Ecology. 2nd ed. Don Mills, Canada: Benjamin/Cummings, 1987.

Freedman, B. Environmental Ecology. 2nd ed. San Diego: Academic Press, 1994.

Gibson, David J. Methods in Comparative Plant Population Ecology. Oxford: Oxford University Press, 2002.

Bill Freedman


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—The full set of paired genetic elements carried by each individual, representing the its genetic blueprint.


—The actual, biological expression in an individual organism of its genetically based information, as influenced by environmental conditions.

Phenotypic plasticity

—The variable degree of expression of genetically based biological potential, in terms of growth form, biochemistry, behavior, etc., depending on environmental circumstances.


—Refers to plants that occur on recently disturbed sites, but only until the intensification of competition related stresses associated with succession eliminates them from the community.

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Science EncyclopediaScience & Philosophy: Octadecanoate to OvenbirdsOpportunistic Species - Environmental Resources And Opportunities, Opportunistic Species In Novel Circumstances