Reconciling theories for metabolic scaling

Area of Science:

• Metabolic ecology
• Theoretical biology
• Physiological ecology

Background:

• Metabolic theory explains organismal metabolic organization and its ecological implications.
• Metabolic scaling is a controversial area in ecology, with ongoing debate about the role of cellular energy supply networks.
• Existing theories often focus on supply-side limitations, leading to discrepancies in scaling relationships.

Purpose of the Study:

• To propose Dynamic Energy Budget (DEB) theory as a unifying framework for metabolic ecology.
• To provide an alternative explanation for physicochemical constraints on individual metabolism.
• To reconcile intra- and interspecific scaling relationships in metabolic rates.

Main Methods:

• Formulating DEB theory to explain metabolic scaling.
• Deriving an equation for metabolic rate scaling in adult heterotrophs based on nutrient assimilation and storage.
• Parameterizing the DEB model using literature data on growth and reproduction.
• Comparing DEB predictions with mammalian respiration data.

Main Results:

• The DEB theory provides a coherent explanation for metabolic scaling by considering nutrient storage and utilization.
• The derived equation for metabolic rate scaling does not rely on optimization or cellular nutrient supply limitation.
• DEB theory successfully explains differences between intra- and interspecific scaling of biological rates with mass.

Conclusions:

• DEB theory offers a robust theoretical underpinning for metabolic ecology, enhancing coherence between different scaling relationships.
• The DEB mechanism, based on universal metabolite storage, applies broadly across taxa.
• This approach provides novel avenues for testing hypotheses regarding metabolic scaling and its underlying mechanisms.