Metabolic Theory of Ecology
Also known as: MTE, metabolic scaling, temperature-size rule, energy allocation
The Metabolic Theory of Ecology (MTE), developed by Brown and colleagues (2004), provides a unifying framework linking individual metabolic rate to ecological patterns across levels of organization (organisms, populations, ecosystems). MTE predicts how metabolic rate scales with body size (allometry) and temperature, and uses these scaling relationships to explain patterns in life history, population growth, community structure, and ecosystem dynamics. The theory is grounded in physics: metabolic rate is constrained by supply of resources (energy and nutrients) and demand determined by biochemical kinetics.
Key highlights
- Unifying framework explaining ecological patterns across scales using first principles (physics and biochemistry)
- Predicts temperature dependence of ecological processes, directly relevant to climate change impacts
- Simple, general model applicable to all ectothermic organisms (most biodiversity)
- Enables prediction of life history and population dynamics from size and temperature data alone
Intuition
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How it works
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When to use it
Use MTE to predict how organisms respond to temperature changes (climate warming), how community composition shifts with organism size, or how ecosystem productivity depends on temperature and biomass. Requires metabolic rate measurements or estimates across multiple body sizes and temperatures.
Strengths & limitations
- Unifying framework explaining ecological patterns across scales using first principles (physics and biochemistry)
- Predicts temperature dependence of ecological processes, directly relevant to climate change impacts
- Simple, general model applicable to all ectothermic organisms (most biodiversity)
- Enables prediction of life history and population dynamics from size and temperature data alone
- Model assumes universal scaling exponents (e.g., a = 2/3 or 3/4), but empirical values vary widely
- Does not account for trade-offs in resource allocation or adaptive evolution; organisms may not follow simple metabolic predictions
- Assumes equilibrium physiology; stress or suboptimal conditions violate assumptions
- Accuracy decreases for heterothermic organisms (birds, mammals) whose metabolic rates deviate from ectothermic predictions
Common pitfalls
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Applications
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Frequently asked
What is the difference between the 2/3 and 3/4 power laws for metabolic scaling?
The 3/4-power law (M^0.75) assumes metabolic rate is limited by resource supply through fractal-like distribution networks. The 2/3-power law (M^0.67) assumes surface-area constraints. Empirically, many organisms show exponents between 2/3 and 3/4; neither is universal. Estimate the exponent for your organisms rather than assuming one value.
How does temperature affect metabolic rate and life history?
Metabolic rate increases exponentially with temperature, following Boltzmann kinetics (e^(-E/kT)). This increases energy consumption and availability for growth and reproduction, accelerating life history (faster maturation, shorter lifespans). Warmer organisms grow faster, mature earlier, and have shorter lifespans than cold counterparts of the same size.
Can I use MTE to predict evolutionary responses to climate change?
MTE predicts ecological (population) responses to temperature change. Evolutionary responses depend on heritable variation in metabolic traits and selection pressure, which MTE does not explicitly model. Use MTE to predict selection pressure (e.g., directional selection for higher temperature tolerance) and combine with quantitative genetic models for evolutionary prediction.
Sources
- 1.Brown, J. H., Gillooly, J. F., Allen, A. P., Savage, V. M., & West, G. B. (2004). Toward a metabolic basis of ecology. Ecology, 85(7), 1771-1789.
- 2.Gillooly, J. F., Brown, J. H., West, G. B., Savage, V. M., & Charnov, E. L. (2001). Effects of size and temperature on metabolic rate. Science, 293(5538), 2248-2251.
- 3.Savage, V. M., Gillooly, J. F., Brown, J. H., West, G. B., & Charnov, E. L. (2004). Effects of body size and temperature on population growth. American Naturalist, 163(3), 429-441.
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ScholarGate. (2026, June 3). Metabolic Theory of Ecology. ScholarGate. https://scholargate.app/ecology/metabolic-theory-of-ecology