Converting Ecological Currencies: Energy, Material, and Information Flows

Effects of organisms beyond resource consumption are vital to explaining ecosystem function and structure. Proposed concepts to organize and understand these effects include trait-mediated indirect interactions and ecosystem engineering, but their integration is non-trivial. Many of these effects can be inter-related by focusing on how matter can act as energy, material and/or information, the currencies of ecological interactions, and therefore act as both a resource and a non-resource depending on the context. We show how converting between these three currencies can be achieved, especially if the effects captured by these currencies are mediated by concentrations of matter. Our framework shows that the joint resource and non-resource effects of matter be considered to understand the structure and function of our human-impacted ecosystems. Understanding how the three currencies of life – energy, material, and information – interact is a key step towards synthesis in ecology and evolution. However, current theory focuses on the role of matter as a resource and energy, and typically ignores how the same matter can have other important effects as a carrier of information or modifier of the environment. Here we present the hypothesis that the dynamic conversion of matter by organisms among its three currencies mediates the structure and function of ecosystems, and that these effects can even supersede the effects of matter as a resource. Humans are changing the information in the environment and this is altering species interactions and flows of matter within and among ecosystems. Understanding how the three currencies of life – energy, material, and information – interact is a key step towards synthesis in ecology and evolution. However, current theory focuses on the role of matter as a resource and energy, and typically ignores how the same matter can have other important effects as a carrier of information or modifier of the environment. Here we present the hypothesis that the dynamic conversion of matter by organisms among its three currencies mediates the structure and function of ecosystems, and that these effects can even supersede the effects of matter as a resource. Humans are changing the information in the environment and this is altering species interactions and flows of matter within and among ecosystems. the movement of an organism in response to a chemical stimulus. matter with stored value in particular states (energy, material, information) that acts as a medium of exchange. ‘The physical modification of the environment by organisms.’ [12.Sanders D. et al.Integrating ecosystem engineering and food webs.Oikos. 2014; 123: 513-524Crossref Scopus (67) Google Scholar] the capacity to perform work. In ecological systems, we generally measure chemical potential energy of substances and heat generated by metabolism. influences organismal activity but is not consumed or depleted by organisms. ‘Two systems a and b coupled in such a way that a’s being (of type, or in state) F is correlated to b being (of type, or in state) G, thus carrying for the observer of a the information that b is G’. [39.Floridi L. The language of information.in: Information: A Very Short Introduction. Oxford University Press, 2010Crossref Google Scholar] ‘Anything is a source of information if it has a range of possible states, and one variable carries information about another to the extent that their states are physically correlated.’ [67.Godfrey-Smith P. Sterelny K. Biological information.in: Zalta E.N. The Stanford Encylopedia of Philosophy. Summer 2016 edn. Metaphysics Research Lab, Stanford University, 2016Google Scholar] in this paper, we refer to the size, shape, texture, electrochemical properties of matter that impact conditions of organisms and processes in ecosystems. physical substance of the world. In ecological systems, we generally consider matter at the atomic level and above. ecosystems that are coupled through the movement of organisms and/or non-living matter. ‘The process whereby organisms, through their metabolism, their activities and their choices, modify their own and/or each other’s niches.’ [11.Odling-Smee J. et al.Niche construction theory: a practical guide for ecologists.Q. Rev. Biol. 2013; 88: 3-28Crossref Scopus (185) Google Scholar] effects of matter that do not involve the direct use by organisms to support their growth and maintenance (e.g., alter environmental conditions or act as information). interactions between species that do not involve direct consumption of matter. substances that organisms use and take up from their environment for their growth and maintenance. organic chemicals released by an organism that can alter the behavior of other organisms. effects of the presence of other species on the trophic interactions of focal species [13.Terry J.C.D. et al.Trophic interaction modifications: an empirical and theoretical framework.Ecol. Lett. 2017; 20: 1219-1230Crossref PubMed Scopus (22) Google Scholar]. organic compounds that have a high vapor pressure at 20°C, resulting in rapid transitions into a gaseous phase from liquid and/or solid form.