Energy Uptake and Allocation during Ontogeny


All organisms face the problem of how to fuel ontogenetic growth. We present a model, empirically grounded in data from birds and mammals, that correctly predicts how growing animals allocate food energy between synthesis of new biomass and maintenance of existing biomass. Previous energy budget models have typically had their bases in rates of either food consumption or metabolic energy expenditure. Our model provides a framework that reconciles these two approaches and highlights the fundamental principles that determine rates of food assimilation and rates of energy allocation to maintenance, biosynthesis, activity, and storage. The model predicts that growth and assimilation rates for all animals should cluster closely around two universal curves. Data for mammals and birds of diverse body sizes and taxa support these predictions.


Biological Sciences

Keywords and Phrases

Bioactivity; Bioenergetics; Biomass; Bird; Body Size; Energy Budget; Energy Flow; Food Consumption; Food Intake; Growth Modeling; Mammal; Metabolism; Ontogeny; Resource Allocation; Taxonomy, Article; Biomass; Bird; Body Growth; Body Size; Calculation; Digestion; Energy Consumption; Energy Expenditure; Food Intake; Mammal; Nonhuman; Ontogeny; Prediction; Priority Journal; Rat; Synthesis, Animals; Basal Metabolism; Biomass; Birds; Body Size; Energy Intake; Energy Metabolism; Female; Food; Growth; Male; Mammals; Mathematics; Models, Biological, Animalia; Aves; Mammalia

International Standard Serial Number (ISSN)


Document Type

Article - Journal

Document Version


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© 2008 American Association for the Advancement of Science (AAAS), All rights reserved.

Publication Date

01 Oct 2008

PubMed ID