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Spatial scaling laws yield a synthetic theory of biodiversity


Ecologists still search for common principles that predict well-known responses of biological diversity to different factors1,2,3,4. Such factors include the number of available niches in space5,6,7, productivity8,9,10, area10, species' body size11,12,13,14 and habitat fragmentation. Here we show that all these patterns can arise from simple constraints on how organisms acquire resources in space. We use spatial scaling laws to describe how species of different sizes find food in patches of varying size and resource concentration. We then derive a mathematical rule for the minimum similarity in size of species that share these resources. This packing rule yields a theory of species diversity that predicts relations between diversity and productivity more effectively thanprevious models8,9,10. Size and diversity patterns for locally coexisting East African grazing mammals and North American savanna plants strongly support these predictions. The theory also predicts relations between diversity and area and between diversity and habitat fragmentation. Thus, spatial scaling laws provide potentially unifying first principles that may explain many important patterns of species diversity.

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Figure 1: Hypothetical distribution of resources, food and habitat, as used by species of different size.
Figure 2: Graphical representation of the conditions for species persistence and coexistence.
Figure 3: Predictions and tests of the scaling law model.


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We thank B. Milne, J. H. Brown, H. DeKroon, J. H. Emlen, S. Gripne, A. Guss, N.Haddad, L. Li, S. Naeem and W. Pitt for comments. Supported by the US NSF, The Netherlands NWO, Santa Fe Institute and USU Ecology Center.

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Correspondence to Mark E. Ritchie.

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Ritchie, M., Olff, H. Spatial scaling laws yield a synthetic theory of biodiversity. Nature 400, 557–560 (1999).

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