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Dynamic Energy Budget Theory: Understanding Reserve Density Dynamics

Explore DEB dynamics, exercises, and interpretations related to reserve density dynamics in an organism. Learn key concepts and computations in energy flows versus mass flows, state variables, and dynamic equations.

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Dynamic Energy Budget Theory: Understanding Reserve Density Dynamics

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  1. DynamicEnergy Budget Theory - I Tânia Sousa withcontributionsfrom : Bas Kooijman

  2. Energyflows vs. Massflows • Fluxes • Parameters = • StateVariables

  3. DEB Dynamics • Thedynamicsofthestate-variables are givenby:

  4. DEB Dynamics • Thedynamicsofthestate-variables are givenby:

  5. Exercises • Obtain an expression for the dynamics of the reserve density mEusingtheequations for thedynamicsof MEand MVandthefollowingequations:

  6. Exercises • Obtain an expression for the dynamics of the reserve density mE • Set dmE/dt=0 (weakhomeostasis). • WhatisthemaximumvalueofmE?

  7. Exercises • Obtain an expression for the dynamics of the reserve density mE • Set dmE/dt=0 (weakhomeostasis). • WhatisthemaximumvalueofmE? • Can youunderstandthemeaning? • Whatisthevalue for mEin weakhomeostasis? -maximumreserve density

  8. Exercises • Obtain an expression for the dynamics of the reserve density mE • Set dmE/dt=0 (weakhomeostasis). • WhatisthemaximumvalueofmE? • Can youunderstandthemeaning? • Whatisthevalue for mEin weakhomeostasis? -maximumreserve density

  9. Exercises • Obtain an expression for the dynamics of the reserve density mE • Set dmE/dt=0 (weakhomeostasis). • WhatisthemaximumvalueofmE? • Can youunderstandthemeaning? • Rewrite usingmEm. -maximumreserve density

  10. Exercises • Obtain an expression for the dynamics of the reserve density mE • Set dmE/dt=0 (weakhomeostasis). • WhatisthemaximumvalueofmE? • Can youunderstandthemeaning? • RewriteusingmEm. Whatisthemeaningof? -maximumreserve density

  11. Exercises • Obtain an expression for the dynamics of the reserve density mE • Set dmE/dt=0 (weakhomeostasis). • WhatisthemaximumvalueofmE? • Can youunderstandthemeaning? • Rewrite usingmEm. Whatisthemeaningof? -maximumreserve density - maximumlength -maximumreserve density

  12. Exercises • What wouldbetheexpression for a parameterthatistheequivalentof for thesomaticmaintenanceassociatedwith volume? • Suggestions: • Write as a functionof - energyspent in themaintenanceofstructurebuiltwith 1 unitof reserve energy per unit time - energyspent in themaintenanceofmaturitybuiltwith 1 unitof reserve energy per unit time

  13. Exercises • What wouldbetheexpression for a parameterthatistheequivalentof for thesomaticmaintenanceproportional to volume? === = - energyspentper unit time inthemaintenanceofstructurethatwasbuiltwith 1 unitof reserve energy - energyspent in themaintenanceofmaturitybuiltwith 1 unitof reserve energy per unit time

  14. A DEB organismAssimilation, dissipationandgrowth • Metabolism in a DEB individual. • Rectangles are state variables • Arrows are flows of foodJXA, reserveJEA, JEC, JEM, JET, JEG, JER, JEJor structureJVG. • Circles are processes • The full square is a fixed allocation rule (the kappa rule) • The full circles are the priority maintenance rule. Feeding ME- Reserve Mobilisation Assimilation Offspring MER MaturityMaintenance Reproduction Growth SomaticMaintenance Maturation MH - Maturity MV - Structure

  15. 3 types of aggregated chemical transformations • Assimilation: X(substrate)+M  E(reserve) + M + P • linked to surface area • Dissipation: E(reserve) +M  M • somatic maintenance: linked to surface area & structural volume • maturity maintenance: linked to maturity • maturation or reproduction overheads • Growth: E(reserve)+M  V(structure) + M • Compounds: • Organic compounds: V, E, X and P • Mineral compounds: CO2, H2O, O2 and Nwaste

  16. Exercises • Identify in theseequationsyXE, yPEandyEV. • Constraintsonthe yield coeficients • Degreesoffreedom

  17. Exercises • Identify in theseequationsyXE, yPEandyEV. • Constraintsonthe yield coeficients • Degreesoffreedom • Obtaintheaggregatedchemicalreactions for assimilation, dissipationandgrowthconsideringthatthechemicalcompositions are: food CH1.8O0.5N0.2, reserve CH2O0.5N0.15, faeces CH1.8O0.5N0.15,structure CH1.8O0.5N0.15and NH3.

  18. Exercises • Identify in theseequationsyXE, yPEandyEV. • Constraintsonthe yield coeficients • Degreesoffreedom • Obtaintheaggregatedchemicalreactions for assimilation, dissipationandgrowthconsideringthatthechemicalcompositions are: food CH1.8O0.5N0.2, reserve CH2O0.5N0.15, faeces CH1.8O0.5N0.15,structure CH1.8O0.5N0.15and NH3. • Howwouldyouobtaintheaggregatechemicaltransformation?

  19. Exercises • What istherelationshipbetweentheseequationsand, ,,, , and .

  20. Exercises • What istherelationshipbetweentheseequationsand, ,,, , and . • Compute the total consumptionof O2. • Writeit as a functionof, and .

  21. Exercises • What istherelationshipbetweentheseequationsand, , , , , and . • Compute the total consumptionof O2. • Writeit as a functionof, and . • Thestoichiometryoftheaggregatechemicaltransformationthatdescribestheorganismhas 3 degreesoffreedom: anyflowproducedorconsumed in theorganismis a weightedaverageofanythreeotherflows

  22. Exercises • Write theenergy balance for eachchemical reactor (assimilation, dissipationandgrowth)

  23. Exercises • Write theenergy balance for eachchemical reactor (assimilation, dissipationandgrowth) • Compute the total metabolicheatproductionas a function of , and .

  24. Exercises • Write theenergy balance for eachchemical reactor (assimilation, dissipationandgrowth) • Compute the total metabolicheatproductionas a function of , and . • Iftheorganismtemperatureisconstantthenthemetabolicheat must beequal to theheatreleased • Indirectcalorimetry (estimatingheatproductionwithoutmeasuringit): Dissipatingheatisweighted sum ofthreemassflows: CO2, O2andnitrogeneouswaste (Lavoisier in the XVIII century).

  25. Dissipating heat Steam from a heap of moist Prunus serotina litter illustrates metabolic heat production by fungi

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