Towards a solution of the plankton paradox: the importance of physiology and life history

Phytoplankton communities reveal an astonishing biodiversity, whereas classical competition theory seems to suggest that only a few competing species can survive. Recently we suggested a new solution to this plankton paradox. In theory, at least, competition between multiple species can generate complex dynamics that can support a large number of species. How likely is it then, in reality, that competitive chaos indeed promotes biodiversity? To obtain some insight, we simulated multispecies competition according to five different physiological scenarios. For random species parameters, biodiversity was generally low. Assuming plausible physiological trade-offs, the simulations revealed switches back and forth between equilibrium and nonequilibrium dynamics, and a higher biodiversity. An extremely high biodiversiry, with sometimes more than 100 species on three resources, was observed in simulations that assumed a cyclic relation between competitive abilities and resource contents. We conclude that physiological and life-history patterns have a major impact on the likelihood of nonequilibrium dynamics and on the biodiversity of plankton communities.