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UA ECOL 437 - ECOL 437 Lecture Notes

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Lecture 27, 09 Dec 2003Chapter 16, Energy Expenditure, Body SizeChapter 17, Environmental ChallengesVertebrate PhysiologyECOL 437University of ArizonaFall 2003instr: Kevin Boninet.a.: Bret Pasch1Vertebrate Physiology 4371. ~Energy Expenditure (CH16)2. Environmental Challenges (Temperature) (CH17)3. Announcements… - Seminar write-up 09 Dec. - Powerpoint (file to us on 09 Dec.) - Oral Presentations 10 Dec. (8min) - Blood Type - Evaluations - Card for guest speaker - Turn in seminar write-ups - Final Exam Tuesday 8 am -Review Sheet2Martin Wikelski, Princeton(16-25)ScalingPower Functions:How do morphology and metabolism change withbody mass?MR = aMbMetabolicrateY-intercept (of log-log plot)BodymassScaling exponent logMR = loga + b(logM)Can look at mass-specific rates by dividing through by MTake logof bothsides(Linearizes)3(16-8)MR = aMbb = 0.75(slope) logMR = loga + b(logM)4(16-7)5Mouse-to-Elephant Curve4g shrew eats 2g/dayelephant is 1 million x larger(16-7)67Knut Schmidt_Nielsen 1972b = 1.13(slope) logMskeleton = loga + b(logM)Isometryis rare8Knut Schmidt_Nielsen 1972Hemoglobin dissociation curves and body size9Knut Schmidt_Nielsen 1972Bohr effect and body size10Knut Schmidt_Nielsen 1972Capillary density and body sizebatratEnergetics of Locomotion-Costly-Rate of O2 consumption increases linearly with speed-rate of increase is less per gram in larger animals-costs small animals more to move each gram(greater drag, less efficient to rapidly contract)(16-13)11Energetics of LocomotionInertial Effects, correlated with Mass1Inertia Resist acceleration2. Momentum In motion tends to stay in motionApplies to whole animals as well as limbs (e.g., cursors)(16-17)12Energetics of LocomotionDrag, viscosity, density…1. Drag = force (~viscosity and density) acting to oppose motion of organisms2. Drag proportional to Surface Area (SA)3. Small animals with relatively large SA and therefore more drag per unit mass4. Drag proportional to SQUARE of velocity(Not too applicable to wholly terrestrial vertebrates.)13Energetics of LocomotionReynold’s Number(p.684)Re = inertia/viscosity-Small animals have low Reynold’s Numbers(viscosity dominates, proportional to SA)-Large animals have high Reynold’s Numbers(inertia dominates, proportional to mass)(p.684)-Shape and size dependent; turbulence-Air Reynold’s lower than Water141. Aquatic Locomotion-relatively efficient b/c neutral buoyancy2. Aerial Locomotion-need to generate lift to fight gravity-airfoil3. Terrestrial rather expensive-Center of Mass up and down (muscles x2)Energetics of LocomotionPenguin?-Consider body shape of aquatic vertebrates vs. aerial vertebrates15(16-20)COSTMode vs. Phylogeny17(16-16)Energetics of LocomotionGait and locomotor mode importantHoppers with elastic energy storage16Terrestrial Gait in Quadrupeds-Walk Æ Trot Æ Gallop-Energy storagenot much Æsome in tendons etc. Æ use whole bodyIntermittent Locomotion-More efficient per unit distance-Gliding in fluid-(Negative Buoyancy)(16-21)18Circadian and other Rhythms (p.688)-link physiology with activity period-more efficient-allows for relaxation/repair -entrained by external stimulus (light, temp.) -larger fluctuations in smaller animals -torpor -hibernation, reproduction, migration etc.(e.g., ~frozen bats?) -in ectotherms harder to separate true circadian rhythms from direct effects of body temperature(16-25)19Pough et al., 200120ThermoregulationTemporal Heterothermy:-Torpor-Hibernation-Estivation(17-35)21aDo Bears Hibernate?Why or Why not?Knut Schmidt_Nielsen 199721bbatsKnut Schmidt_Nielsen 1997Knut Schmidt_Nielsen 199721cbirdsReproductionParental Care:not typical, but...Stebbins and Cohen, 1995Stebbins and Cohen, 1995Darwin frog, vocal sacEnergetics of Reproduction p. 6932223K vs. r selected(logistic curve)-Larger animals investproportionally less inreproduction-Sperm is cheap-Direct and indirect costs-Fetal teeth in caecilians-Male emperor penguin>100days w/o food whenincubating eggsKnut Schmidt_Nielsen 1997(17-11)24Thermal Neutral Zone(17-21)Within TNZ:-Vasomotor-Posture-Insulation fluff fur/feathersCritical TemperatureUpper LowerBelow TNZ:-Increase metabolism above basalAbove TNZ:-Cool via evaporation25Temperature Set Point(season, reproductive state, infection)Hypothalamus functionsas thermostatPough et al., 2001Physiology and BehaviorNeuronal Control of Thermoregulation(17-27)26ThermogenesisShivering (or locomotion)antagonistic muscle contractionsheat byproductNon-shiveringfats metabolized, but produce heat instead of ATPbrown fat specialized sympathetic stimulation:1. ATP hydrolysis used to pump ions needlessly2. Proton leakage in mitochondria,rather than production of ATPin presence of thermogeninEndotherms in the COLD…27STUDENTSLOOK UPEndotherms in the COLD…Shivering (or locomotion)-antagonistic muscle contractions heat byproductNon-shiveringfats metabolized, but produce heat instead of ATP- brown fat specialized Thermogenesis(17-22)28STUDENTSLOOK UPHeat Windows(17-28)Rabbit EarsGuanaco29SKIPPED, BUT IN YOUR BOOKThermoregulationCardiovascular control of heating and cooling- Cardiac Shunts- Peripheral VasodilationPough et al., 2001Pough et al., 200130SKIPPED, BUT IN YOUR BOOKRates ofHeating andCoolingCountercurrent Heat ExchangeEndotherms in the COLD…31aSKIPPED, BUT IN YOUR BOOKKnut Schmidt_Nielsen 199731bSKIPPED, BUT IN YOUR BOOKHot Body, Cool BrainKeep brain cool during prolongedincreased organismal activity:-Countercurrent-Carotid Rete(17-33)32SKIPPED, BUT IN YOUR BOOKMicrohabitat(17-10)33SKIPPED, BUT IN YOUR BOOKPyrogensFever(17-36)Dipsosaurusdorsalis34SKIPPED, BUT IN YOUR BOOKDEBATEWould you rather be an ectotherm or an endotherm?COST/BENEFIT ANALYSIS35SKIPPED, BUT CONCEPTS IN YOUR BOOKEctothermy vs. Endothermy•Ectotherms-lower metabolic rate-require less water-require less food (foraging time)-greater proportion energy into growth and repro-small body size works (different shapes)-reliant on environmental heat sources-seasonal and daily limits on activity-low aerobic capacities2. Endotherms with ‘opposite’ costs and benefits36SKIPPED, BUT CONCEPTS IN YOUR BOOKMuch more difficult for water breathing animals tomaintain body temperatures above ambient becauserate of heat transfer is greater than rate of O2 transferin water (high specific heat)Amblyrhynchus cristatus37Knut Schmidt_Nielsen 1997SKIPPED, BUT CONCEPTS IN YOUR BOOKFish


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