Very Short Term. Low ATP demand, charge system. High ATP demand, supply P. Short Term Storage. High insulin, glycogenesis

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1 Energy Storage ATP Very Short Term Low ATP demand, charge system High ATP demand, supply P Creatine Blood Glucose Levels Short Term Storage High insulin, glycogenesis Low glucagon, glycogenolysis Glycogen Acetyl-CoA Long Term Storage Insulin - lipogenesis Epinephrine, glucagon - Lipolysis Lipids 1

2 Animals use energy in hierarchy Phosphagen system Anaerobic Aerobic Oxygen Debt and Exercise Ability to supply oxygen usually lags behind energy use Phosphagen, anaerobic sources used, incurring an oxygen debt 2

Energetics Energy Input Waste (feces) Absorbed Net Energy Input Waste (urine) Specific

3 Measuring metabolic rate Energy in energy out Oxygen consumed or CO 2 released Heat production Production of metabolic water Complications with each approach Metabolism and Energetics Energy Input Waste (feces) Absorbed Net Energy Input Waste (urine) Specific Dynamic Action Maintenance Work (muscular) Production Heat Growth (somatic/fat) Reproduction 3

4 Measures of metabolic rate Metabolic rate is expected to be variable based on what an animal is doing, environmental conditions etc. Standard (basal) metabolic rate (SMR/BMR) primarily maintenance, no specific dynamic action (SDA) or movement Routine metabolic rate (RMR) resting rate not well defined Field metabolic rate (FMR) average metabolic rate over a 24 hour period of typical activity. Active metabolic rate metabolic rate to carry out a specific activity or exercise. Maximum metabolic rate peak rate during maximum activity. Scope Absolute aerobic scope difference between minimum (standard/basal) and maximum rates Factorial aerobic scope ratio between minimum and maximum Sustained scope difference between BMR and sustained rates 4

5 Next Class Reading Metabolic rate and body size M = 70 mass 0.74 Slope intermediate to expectations based on surface area and mass alone Note differences between endotherms (39C) and ectotherms (20C). Temperature and body size are the best predictors of metabolic rate. 5

size (capillary) is constant, not allometric Energy required to supply network should be

6 Mass-specific metabolic rates Mass specific metabolic rate almost 200x greater for shrew than blue whale Assumptions Network of branching vessels supports all tissue Final branch size (capillary) is constant, not allometric Energy required to supply network should be minimized Larger animals require proportionately fewer branches in the network to supply all cells 6

Metabolic Regulators Metabolic regulators metabolic rate constant as environmental O 2 changes

rates at certain times Torpor short term reduction in metabolic rate Aestivation prolonged summer

based on Length and depth of torpor Body size Ambient temperature Arousing from torpor is estimated

7 Metabolic Regulators Metabolic regulators metabolic rate constant as environmental O 2 changes Metabolic conformers metabolic rate changes with O 2 levels Hypometabolism decreasing metabolic rates at certain times Torpor short term reduction in metabolic rate Aestivation prolonged summer torpor Hibernation prolonged winter torpor Cost/benefit of torpor Energetic savings from torpor based on Length and depth of torpor Body size Ambient temperature Arousing from torpor is estimated to be up to 75% of total cost Bats and white nose disease Recall night roosting energy savings for hummingbirds 7

8 Temperature and metabolism Temperature and metabolic rate tightly linked in ectotherms Q 10 rate increase in a process over a 10 C o increment. Typically 2-3 for metabolic rates Endotherms expect increase at low temperature to maintain body temperature Torpor, aestivation, hibernation Endotherm Metabolism and Temperature Costs to maintain body when cold can be high Body size Insulation Available microhabitats Aquatic vs. terrestrial Avoidance Spatial (migrate) Temporal (torpor) Tolerance Metabolic Rate Energy demand to counter heat loss (stress) Zone of Thermal Neutrality Ambient Temperature Thermal stress 8

9 Metabolic Cold Adaptation (MCA) Ectotherm metabolic rate tightly linked with environmental temperature Warm climate population Cold climate population As you move away from the equator Mean annual temperature lower Length of growing season shorter MCA selects for elevated metabolic rates Metabolic Rate Temperature Optimal Temperatures For larval salmon, fitness measured as accumulation of mass (growth) Growth rate and metabolic rate maximized at 7.3 C for salmon 9

Specific tissues Heart and skeletal muscle have

production/storage mechanisms Constraints to

cardiovascular limits Tolerance to byproducts

Evolutionary context selection should favor

10 Specific tissues Heart and skeletal muscle have different capacities for various ATP production/storage mechanisms Constraints to maximum metabolism Heat production Gas exchange, cardiovascular limits Tolerance to byproducts Muscle capacity (mitochondrial packing) Evolutionary context selection should favor adaptations that maximize energy allocation to reproduction in that particular environment 10

11 Variation in Energy Budgets Season and sex variation in allocation to production (growth + reproduction) 11

2/23/2015. Metabolism and Energetcis. Metabolism and Energetics. Metabolism and Energetics

2/23/2015. Metabolism and Energetcis. Metabolism and Energetics. Metabolism and Energetics 8 6 Metabolism and Energetcis Simple energy budget Calories ingested = Calories used + growth Frequency 4 Currency is typically (kilo)calories 1 calorie 1 g water 1 C o 4.2 Joules 2 0 90-100 80-90 70-80