A metabolic view of the diversity-stability relationship.

A theoretical analysis of the "portfolio effect" expressed in metabolic terms indicates that the coefficient of variation of total biomass in the ecosystem is influenced by three factors: metabolic diversity, total population size and organism biomass (body mass). The contribution of these factors to ecosystem stability depends on the power scaling of population size to its temporal variance: the Tilman's z. In natural populations, 1 < z < 2 both from a theoretical and an empirical background, and so a higher metabolic diversity, a larger population size and a bigger body mass are expected to increase ecosystem stability. The maximization of any of these factors will enhance ecosystem stability both at ecological (successional) and evolutionary timescales, which could explain a number of trends observed in ecosystems and in the history of life.