López-Villalta Julián Simón
Departamento de Ecología, Universidad Autónoma de Madrid, Cantoblanco, 28040 Madrid, Spain.
J Theor Biol. 2008 May 7;252(1):39-42. doi: 10.1016/j.jtbi.2008.01.015. Epub 2008 Jan 26.
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.
从代谢角度对“组合效应”进行的理论分析表明，生态系统中总生物量的变异系数受三个因素影响：代谢多样性、总种群规模和生物体生物量（体重）。这些因素对生态系统稳定性的贡献取决于种群规模与其时间方差的幂次缩放：即蒂尔曼的z值。从理论和实证背景来看，自然种群中1 < z < 2，因此更高的代谢多样性、更大的种群规模和更大的体重有望提高生态系统稳定性。这些因素中任何一个的最大化都将在生态（演替）和进化时间尺度上增强生态系统稳定性，这可以解释在生态系统和生命历史中观察到的一些趋势。
