Fair game dynamics and ecological equivalence in a tropical forest
Understanding the mechanisms that maintain biodiversity is a core issue in ecology. Classic ecological theory asserts that stable coexistence requires ecological differences among species whilst neutral theory assumes that individual organisms are ecologically equivalent and explains species coexistence and composition by stochastic processes. Here we show that neutral theory in ecology is analogous to the prevalent ‘efficient market theory’ in economics: a financial system model where future earnings are distributed between competing players according to a ‘fair game’. This analogy allows using powerful methods from econometrics for testing neutral theory in ecology, in particular ‘panel data analysis’ of large numbers of short time-series observed from the same system. Such ecological panel data exist for tropical forests.
We found that species abundance dynamics in such a forest remain in striking agreement with ‘fair game’ dynamics and hence with the predictions of neutral theory. More generally, our findings suggest that complex dynamical systems, such as tropical forests and financial markets, share unexpected common features and so further methods may prove valuable when transferred between the two fields.