Why do so many species live in tropical forests and coral reefs?

The latest development in a major debate over a controversial hypothesis of biodiversity and species abundance is the subject of a paper would be reported in the 1 November 2007 issue of the journal Nature. The authors report good agreement between the species richness of two of the world's most vulnerable ecosystems -- tropical forests and coral reefs -- and a simple mathematical model building on the so-called "neutral theory of biodiversity." "We're helping to refine and improve this theory because it might have important implications for the effort to protect terrestrial biodiversity from climate change and urban development," says Jayanth Banavar of the Department of Physics at Penn State, a member of the research team.

The Nature paper is based on a counterintuitive assumption of neutral theory: that one can largely ignore interactions between species in modeling patterns of species abundance. The authors are physicists Igor Volkov and Jayanth Banavar of Penn State University, plant biologist Stephen Hubbell of UCLA (formerly of the University of Georgia), and physicist Amos Maritan of the University of Padua in Italy.

Among ecological theorists, neutral theory has sparked a six-year quarrel over the fundamental assumptions of their discipline. The Nature paper counters another scientific team's claim in 2006 that coral-reef diversity "refutes" the neutral theory. At the same time, the paper by Volkov et al., would be published on 1 November 2007, modifies the classical version of neutral theory that appeared in a 2001 book by Hubbell. (Graham Bell of McGill University also developed a neutral theory independently of Hubbell.) Banavar, Maritan, Volkov, and their collaborators have been active in the development of a mathematical framework for understanding ecosystems that builds on and clarifies Hubbell's neutral theory...
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