Self-organized similarity, the evolutionary emergence of groups of similar species
- Aquatic Ecology and Water Quality Management Group, Department of Environmental Sciences, Wageningen University, P.O. Box 8080, 6700 DD, Wageningen, The Netherlands
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Edited by Stephen R. Carpenter, University of Wisconsin, Madison, WI, and approved February 21, 2006 (received for review September 16, 2005)
Abstract
Ecologists have long been puzzled by the fact that there are so many similar species in nature. Here we show that self-organized clusters of look-a-likes may emerge spontaneously from coevolution of competitors. The explanation is that there are two alternative ways to survive together: being sufficiently different or being sufficiently similar. Using a model based on classical competition theory, we demonstrate a tendency for evolutionary emergence of regularly spaced lumps of similar species along a niche axis. Indeed, such lumpy patterns are commonly observed in size distributions of organisms ranging from algae, zooplankton, and beetles to birds and mammals, and could not be well explained by earlier theory. Our results suggest that these patterns may represent self-constructed niches emerging from competitive interactions. A corollary of our findings is that, whereas in species-poor communities sympatric speciation and invasion of open niches is possible, species-saturated communities may be characterized by convergent evolution and invasion by look-a-likes.
Footnotes
- *To whom correspondence should be addressed. E-mail: marten.scheffer{at}wur.nl
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See Commentary on page 6083.
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Author contributions: M.S. and E.H.v.N. designed research, performed research, and wrote the paper.
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Conflict of interest statement: No conflicts declared.
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This paper was submitted directly (Track II) to the PNAS office.
- © 2006 by The National Academy of Sciences of the USA
