# Metabolic Theory of Ecology **Entity class:** Scientific theory **Domain:** Ecology / Bioenergetics / Complex Systems **Doc Type:** Specialized Scientific Branch Node **Maturity:** Developed ## Definition The **Metabolic Theory of Ecology**, commonly abbreviated **MTE**, uses metabolism as a common quantitative basis for connecting organismal biology to ecological organization. It asks how body size, temperature and metabolic rate constrain the pace at which organisms take up resources, grow, reproduce, interact and return matter and energy to their environments. Within this vault, MTE is the established ecological branch of the broader [[wiki/Metabolic Stack|Metabolic Stack]]. The Stack also includes social, cognitive, institutional, cultural, civilizational and computational branches while preserving their different evidentiary status. ## From organism to ecosystem Metabolic rate is the rate at which an organism acquires, transforms and expends energy and material. MTE begins with the [[wiki/Allometric Scaling|allometric]] relation between body size and metabolism, including the tradition represented by [[wiki/Kleiber's Law|Kleiber's law]] and the [[wiki/West-Brown-Enquist Model|West-Brown-Enquist model]], then projects those energetic constraints across levels of ecological organization. The theory makes predictions about life-history rates, population growth, carrying capacity, competition, predation, biomass production, respiration and trophic dynamics. Its organizing proposition is that ecological processes do not float above physiology; they inherit a pace from the organisms performing them and from the temperatures under which those organisms operate. ## Why metabolism matters ontologically A system has a metabolism when it must maintain organized activity through continuing throughput. It receives resources, transforms them, performs work and exports waste. [[wiki/Systems Ecology|Systems ecology]] studies those flows at the ecosystem level; MTE attempts to connect their rates to organismal energetic constraints. Bryant's corpus extends metabolic questions to institutions and computational systems. That extension is conceptual unless the relevant inputs, transformations, outputs and scaling relations are measured. [[wiki/Computational Metabolism|Computational metabolism]] names a different substrate with its own variables; it is not an instance of MTE merely because both use the word *metabolism*. ## The absorptive-system connection An absorptive system is not defined only by what enters it, but by what the larger organization does with what enters. A culture, institution or city can recruit people, attention and resources into a maintained pattern; however, ecological metabolism and social absorption remain distinct claims. MTE contributes the discipline of tracing throughput across levels. The social interpretation must still identify the actual channels of acquisition, transformation, retention and waste. ## Evidence boundary - **Established:** Body size, temperature and metabolism are major predictors of many biological and ecological rates. - **Theoretical:** MTE seeks a unified quantitative account of processes ranging from organisms to ecosystems. - **Variable by application:** Particular predictions depend on taxa, environment, measured rate and model assumptions. - **Interpretive:** Calling an institution metabolic identifies flows to measure; it does not make the institution a biological organism. ## Relationships - **Quantitative foundation:** [[wiki/Allometric Scaling|Allometric Scaling]] · [[wiki/Kleiber's Law|Kleiber's Law]] · [[wiki/West-Brown-Enquist Model|West-Brown-Enquist Model]] - **Ecological context:** [[wiki/Ecology|Ecology]] · [[wiki/Systems Ecology|Systems Ecology]] · [[wiki/Human Ecology|Human Ecology]] - **Cross-substrate comparison:** [[wiki/Computational Metabolism|Computational Metabolism]] · [[wiki/Dissipative Structure|Dissipative Structure]] - **Parent ontology:** [[wiki/Metabolic Stack|Metabolic Stack]] - **Social comparison:** [[wiki/Urban Scaling|Urban Scaling]] - **Corpus application:** [[blog/20170722 - The Atmospheres We Carry|The Atmospheres We Carry]] ## Primary source - James H. Brown, James F. Gillooly, Andrew P. Allen, Van M. Savage and Geoffrey B. West, [“Toward a Metabolic Theory of Ecology”](https://doi.org/10.1890/03-9000), *Ecology* 85, no. 7 (2004): 1771–1789.