Metabolism. -Chemical reactions in the body -Temperature-dependent rates -Not 100% efficient, energy lost as heat (not lost if used to maintain Tb)

Transcription

1 Metabolism 58

2 Metabolism -Chemical reactions in the body -Temperature-dependent rates -Not 100% efficient, energy lost as heat (not lost if used to maintain Tb) 1. Anabolic -creation, assembly, repair, growth (positive nitrogen balance) 2. Catabolic -energy release from complex molecules (carbos, fats, proteins) -energy storage in phosphate bonds (ATP) and metabolic intermediates (glucose, lactate) 59

3 Chemical Energy (Eckert 16-1) 60

4 10% Rule Hill et al. 2004, Fig

5 Metabolism Energy Available for: - Growth, Maintenance, Reproduction - SDA (specific dynamic action) No free lunch! (Hill et al. 5.5) 62

6 Metabolism and Ecology Male emperor penguin >100days w/o food when incubating eggs Knut Schmidt_Nielsen

7 Metabolism and Ecology K vs. r selected (logistic curve) -Larger animals invest proportionally less in reproduction -Sperm is cheap -Direct and indirect costs 64

8 Fetal teeth in caecilians Fig Stebbins and Cohen, 1995 Fig. 5-5 Duellman and Trueb,

9 Metabolic Rate -measurable conversion of chemical energy into heat -used to understand: -energy budgets -dietary needs -body size implications -habitat effects -costs of various activities -mode of locomotion -cost of reproduction 66

10 Much more difficult for water breathing animals to maintain body temperatures above ambient because rate of heat transfer is greater than rate of O 2 transfer in water (high specific heat) Amblyrhynchus cristatus Knut Schmidt_Nielsen

11 Fish Example: -Differences in vascular organization -Tuna with warm, aerobic muscle medially -Countercurrent blood flow (don t lose heat to cold water across gills) (17-19) 68

12 Knut Schmidt_Nielsen

13 Metabolic Rates -Basal Metabolic Rate, BMR -minimal environmental and physiological stress (appropriate ambient temperature, post-digestive, resting etc.) -Standard Metabolic Rate, SMR -similar to BMR, but at a given Tb -Field Metabolic Rate, FMR -average metabolic rate of animal in natural setting -hard to measure 70

14 birds Knut Schmidt_Nielsen 1997 Knut Schmidt_Nielsen

15 Metabolic Rates Basal Metabolic Rate, BMR -important components: 1. Membrane form and function maintenance of electrochemical gradients -proton pumps in mitochondrial membranes -Na/K-ATPase pumps in plasma membrane 2. Protein synthesis 3. ATP formation 72

16 73

17 Metabolic heat production (chemical energy lost as heat during metabolism) -Endotherms -surface area to volume ratio -Larger ectotherms can be heterothermic - leatherback (Dermochelys coriacea) - pythons (female brooding clutch) - tuna and increased core temperature Pough et al.,

18 Allometry: 75

19 Allometry Mouse-to-Elephant Curve 4g shrew eats 2g/day elephant is 1 million x larger (Eckert 16-7) 76

20 Allometry x 6 1 week of food x 0.3 (Hill et al. 5.6) 77

21 Allometry (Eckert 16-8) MR = am b b = 0.75 logmr = loga + b(logm) (slope) 78

22 Scaling How do morphology and metabolism change with body mass? Body Power Functions: mass Scaling exponent MR = am b Take log of both sides Metabolic rate logmr = loga + b(logm) Y-intercept (of log-log plot) (Linearizes) 79 Can look at mass-specific rates by dividing through by M

23 Allometry (Eckert 16-7) 80

24 logm skeleton = loga + b(logm) Isometry is rare b = 1.13 (slope) Knut Schmidt_Nielsen

25 Allometry Locomotor Mode COST (Eckert 16-20) 82

26 Scaling Effects Allometry - changes in body proportions as animals get larger (mouse vs. elephant) Metabolic Rate - mass-specific metabolic rate decreases with increasing body mass (16-6) linear cubed squared 83

27 Allometry Knut Schmidt_Nielsen mg/kg 0.2mg for 70 kg (a) = elephant freaked out and died (1960 s) in a study of musth [elephantine fallacy] -What is the correct dose? -Importance of Scaling! 84

28 Allometry Hemoglobin dissociation curves and body size Knut Schmidt_Nielsen

29 Allometry Bohr effect and body size 86 Knut Schmidt_Nielsen 1972

30 Allometry bat Capillary density and body size rat Knut Schmidt_Nielsen