Leaving Out the Details

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Science  04 Aug 2006:
Vol. 313, Issue 5787, pp. 592
DOI: 10.1126/science.313.5787.592c

The species-area relationship (SAR) is a well-studied concept in ecology and biogeography, relating area to the total number of species found within it. The relationship takes the form of a power law S = cAz, where S is the number of species, A is the area, and c is a constant. The exponent z varies from as little as 0.5 to as much as 1.0, according to the group of organism, the scale in question, and the habitat type, but is most commonly found to lie in the range of 0.2 to 0.3. However, the factors underlying this relationship, and the reasons for the variation in z, have remained enigmatic.

In a new theoretical treatment of the question, García Martín and Goldenfeld show that the observed relationship and the value of z flow from the statistical properties of spatial and abundance distributions, such as clustering and mean distance between individuals, rather than directly from any ecological property of organisms and ecosystems (competition, dispersal, etc.) They validate the theory using data from a grassland site in California. — AMS

Proc. Natl. Acad. Sci. U.S.A. 103, 10310 (2006).

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