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Copyright ©1999 by The Resilience Alliance*

Correct format for citing this article:
Piraino, S., and G. Fanelli. 1999. Keystone species: what are we talking about? Conservation Ecology 3(1): r4. [online] URL: http://www.consecol.org/vol3/iss1/resp4/


Response to Khanina 1998. "Determining keystone species"

Keystone Species: What Are We Talking About?

Stefano Piraino and Giovanni Fanelli


Istituto Sperimentale Talassografico C.N.R., Taranto

Science is often challenged by misuse of terminology. In most cases, this is due to an incomplete review of the literature. In spite of recent recommendations (Paine 1996), terms like "species' functional roles" are still used in a confused way, and original definitions are often misinterpreted. The "keystone species" concept (Paine 1966, 1969) is a case in point. In recent years, the overly expansive usage of the keystone concept has led to a redefinition of the term. According to the current interpretation (Power and Mills 1995, Power et al. 1996), keystones are only those species having a large, disproportionate effect, with respect to their biomass or abundance, on their community. Some operational tools are now available to distinguish not only between strong and weak interactors, but also between keystone and dominant species (Paine 1992, Navarrete and Menge 1996, Power et al. 1996, Hurlbert 1997). Khanina (1998) is the latest (but certainly not the last) author attributing the keystone status to dominant species or even to dominants with structural roles (see, for instance, MacIsaac et al. 1995, Procaccini et al. 1996, Hacker and Gaines 1997). Moreover, those species driving ecosystem processes or energy flows are generally referred as "key" species, but only a few of them are keystones. Putting keystones and key species in the same melting pot, as Khanina (1998) does, should be avoided. Therefore, trees and bisons are not keystones, just as the original keystone species identified by Paine was not the dominant mussel, but its starfish predator.

Published April 1, 1999.


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LITERATURE CITED

Hacker, S. D., and S. D. Gaines. 1997. Some implications of direct positive interactions for community species diversity. Ecology 78: 1990-2003.

Hurlbert, S. H. 1997. Functional importance vs. keystoneness: reformulating some questions in theoretical biocenology. Australian Journal of Ecology 22:369-382.

Khanina, L. 1998. Determining keystone species. Conservation Ecology 2(2):R2. [online] URL:http://www.consecol.org/Journal/vol2/iss2/resp2.

MacIsaac, H. J., J. H Leach, G. D. Haffner, R. W. Bachmann, J. R. Jones, R. H Peters, and D. M. Soballe, editors. 1995. Ecological and ecotoxicological changes in the western Lake Erie following zebra mussel invasion. Lake Reserve Management 11: 163-164.

Navarrete, S. A., and B. Menge. 1996. Keystone predation and interaction strength: interactive effects of predators on their main prey. Ecological Monographs 66:409-429.

Paine, R. T. 1966.Food web complexity and species diversity. American Naturalist 100: 65-75.

_______ . 1969. A note on trophic complexity and species diversity. American Naturalist 103:91-93

_______ . 1992. Food-web analysis through field measurement of per capita interaction strength. Nature 355: 73-75.

_______ . 1996. Preface. Pages ix-x in G. A. Polis and K. O. Winemiller, editors. Food webs: integration of patterns and dynamics. Chapman and Hall, London, UK.

Power, M. E., and L. S. Mills. 1995. The keystone cops meet in Hilo. Trends in Ecology and Evolution 10:182-184.

Power, M. E., D. Tilman, J. A. Estes, B. A. Menge, W. J. Bond, L. S. Mills, D. Gretchen, J. C. Castilla, J. Lubchenco, and R. T. Paine. 1996. Challenges in the quest for keystones. BioScience 46: 609-620.

Procaccini, G., R. S. Alberte, and L. Mazzella. 1996. Genetic structure of the seagrass Posidonia oceanica in the Western Mediterranean: ecological implications. Marine Ecology Progress Series 140:153-160.


Address of Correspondent:
Stefano Piraino
Istituto Sperimentale Talassografico CNR, Via Roma 3, 74100
Taranto, Italy
Phone: 39 99 4542209
Fax: 39 99 4542215
piraino@istta.le.cnr.it

*The copyright to this article passed from the Ecological Society of America to the Resilience Alliance on 1 January 2000.

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