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TEMPERATURE

TEMPERATURE. 350 o C (662 F). Prokaryotes (bacteria, cyanobacteria) span almost the entire range of Earth’s Temperatures. Vertebrates can tolerate only a small portion of this range. Deep sea Hydrothermal vents. Few Species of Fish 44 o C. 0 o C (32 F). Large Polar Mammals -60 o C.

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TEMPERATURE

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  1. TEMPERATURE

  2. 350 oC (662 F) • Prokaryotes (bacteria, cyanobacteria) span almost the entire range of Earth’s Temperatures. • Vertebrates can tolerate only a small portion of this range. Deep sea Hydrothermal vents Few Species of Fish 44 oC 0 oC (32 F) Large Polar Mammals -60 oC -89 oC -128 F Antarctica

  3. Temperature sets limits… Physiology Morphology Behavior performance Darwinian fitness Environment

  4. Biochemical structures (i.e. enzymes) breakdown Rate of reaction Increasing T Limits at the Cellular Level Increased Temperature speeds up biochemical reactions… …to a point

  5. Thermal performance curves: specialist generalist Performance Lower lethal temp Upper lethal temp Temperature … but limits are species-specific

  6. Temperature Outline • Definitions: • Heat Transfer • Physiological strategy: endo, ecto, etc. • Temperature tolerance • Extreme Temperature: HEAT • Death? • Avoidance strategies • Tolerance strategies • Extreme Temperature: COLD • Death? • Avoidance strategies • Tolerance strategies • Example: Camels are cool!

  7. Temperature Basics • Heat Transfer • Thermal Strategies • Thermal Tolerance

  8. Heat transfer between animals and environment

  9. What’s the difference between temperature & heat? Measure of intensity of heat Total KE (calories or joules) (oC, oF, K) Same temp, Different heat content 1 Calorie = energy required to raise 1g of water 1o C How many calories to heat 1g water from 25o C to 50o C? = 25 calories How many calories to heat 100g water from 25o C to 50o C? = 2500 calories

  10. Heat production - + Heat in Heat out (metabolism) = Heat stored Body temperature depends on heat stored Gains > losses

  11. Heat flows from warmer cooler 4 Mechanisms of heat transfer • Conduction • Conduction + Convection • Radiation • Evaporation “The Rules” Greater temperature gradient, greater flux Physical properties matter

  12. 1. Conduction = heat transfer between bodies in direct physical contact • temperature differential • area of contact • conductivity of materials

  13. 2. Convection CONDUCTION ONLY CONDUCTION AND CONVECTION Hot object Hot object = bulk movement of fluid - Accelerates heat transfer between a solid and a fluid Why? Boundary Layer is Removed

  14. 2. Convection …All fluids come to rest at a solid surface Air reaches full speed Air reaches full speed = “boundary layer” Fluid speed 0 Distance from solid surface Size of boundary layer is influenced by: Thicker boundary layer, less heat loss to conduction • size (and shape) of animal • surface roughness • fluid speed (air, H2O)

  15. 3. Radiation Short wavelengths ∞ Surface temperature is important: -intensity T4 Long wavelengths = transfer of heat between objects without contact Above absolute zero, all objects emit & receive radiation -hotter surface, shorter wavelengths Area of radiative surface is, too

  16. 4. Evaporation =Extremely effective method of losing heat @ 35o C, it takes 580 cal to vaporize 1g of H2O! • exposure of moist surfaces • moisture gradient

  17. 4. Evaporation =Extremely effective method of losing heat @ 35o C, it takes 580 cal to vaporize 1g of H2O! • exposure of moist surfaces • moisture gradient

  18. Heat flux from different sources is additive Infrared thermal radiation from lizard Infrared thermal radiation from atmosphere Direct sunlight Evaporation Convection by wind Conduction from rock Infrared thermal radiation from rock

  19. Temperature Basics • Heat Transfer • Conduction • Convection • Radiation • Evaporation • Thermal Strategies • Thermal Tolerance

  20. Thermal Strategies • Ectotherms: a body temperature principally dependent on external heat sources • Endotherms: a body temperature principally dependent on internally generated metabolic heat • Homeotherms: body temperature kept constant • Poikilotherms: body temperature varies

  21. Some small birds and mammals Brooding Python A few fish MR MR Tb Tb Ta Ta ENDOTHERMS Terrestrial Birds and Mammals POIKILOTHERMY HOMEOTHERMY Polar Marine Fish Most Amphibians and Reptiles A few Amph and Rept Freshwater Fish Most Marine Fish ECTOTHERMS

  22. Temperature Basics • Heat Transfer • Conduction • Convection • Radiation • Evaporation • Thermal Strategies • Endotherm vs Ectotherm • Homeothermy vs Poikilothermy • Thermal Tolerance

  23. Thermal performance curves: Preferred Body Temp Performance Temperature

  24. Thermal performance curves: Preferred Body Temp Performance Temperature Environmental Temperature shift? ACCLIMITIZATION!!

  25. Will discuss in hot vs. cold Temperature Acclimatization • Behavioral • Morphological • Physiological • Biochemical • Membrane dynamics • Enzyme types and concentrations • Heat Shock Proteins

  26. Membrane Dynamics What are the kinks?

  27. Polyunsaturated Fatty Acid (Omega 6)

  28. Temperature also has major effects on cell membrane fluidity If you live in hot climate, what sort of fatty acids should you have? If you live in cold climate, what sort of fatty acids should you have?

  29. Cage Floor temperature Diet very high in unsaturated fats Normal Diet Common Shingleback

  30. Thermal performance curves: Preferred Body Temp Performance Temperature Environmental Temperature shift? Increase PUFA in diet!

  31. Enzymes = different forms of particular enzymes with different temperature optima • isozymes 4 different forms of ATPase Each with a separate thermal performance curve

  32. Alligator lizard Fence lizard Desert Fringed Lizard Desert Iguana Enzymes • isozymes

  33. Heat Shock Proteins • Under High Temperatures, Proteins unfold (denature) How can you protect Cells during protein denaturation?

  34. “Heat Shock Proteins” protect against heat damage • = proteins synthesized in response to cellular stress (including high temps) • function as “molecular chaperones” Heat increases Protein denatures from Heat HSP expression increases (more HSP) HSP binds up denatured protein Heat decreases HSP lets go, protein can refold

  35. Cataglyphis Ants >50C on sand 45C in nest entrance Cataglyphis spend 10-15 minutes In the tunnel to the nest, making heat shock proteins to protect their cells while they are out on the desert foraging Other insects stop foraging <30C inside nest http://www.youtube.com/watch?v=w9KDM4C1kVg&feature=related

  36. Temperature Acclimatization • Biochemical • Membrane dynamics • Colder? Incoporate more PUFA • Hotter? Use less PUFA • Enzyme types and concentrations • Colder or hotter? Change isozyme Goldfish Swimming Speed

  37. Temperature Acclimatization • Biochemical • Membrane dynamics • Colder? Incoporate more PUFA • Hotter? Use less PUFA • Enzyme types and concentrations • Colder or hotter? Change isozyme • Heat Shock Proteins • Protect protein denaturation from killing cells

  38. Temperature Basics • Heat Transfer • Conduction • Convection • Radiation • Evaporation • Thermal Strategies • Endotherm vs Ectotherm • Homeothermy vs Poikilothermy • Thermal Tolerance • Acclimatization of membranes and enzymes

  39. Temperature Outline • Definitions: • Heat Transfer • Physiological strategy: endo, ecto, etc. • Temperature tolerance • Extreme Temperature: HEAT • Death? • Avoidance strategies • Tolerance strategies • Extreme Temperature: COLD • Death? • Avoidance strategies • Tolerance strategies • Example: Camels are cool!

  40. HEAT • What causes death? • Avoidance Strategies • Tolerance Strategies

  41. Acetylcholinesterase What ultimately causes heat death? • Disruption of membrane integrity • Exceeding optimal temp for enzyme function temperature optima vary by species

  42. What ultimately causes heat death? • Disruption of membrane integrity • Exceeding optimal temp for enzyme function • Protein Denaturation

  43. HEAT • What causes death? • Membrane disruption • Enzyme function • Protein denaturation • Avoidance Strategies • Tolerance Strategies

  44. Metabolic rates reduced Thermal tolerance limits expanded Growth and reproduction cease Animal becomes relatively unresponsive to external stimuli Estivation = ‘summer sleep’ Avoidance Strategies Migration • Spend part of the year in different location

  45. Tolerance Strategies: 1 (behavioral) Alter Heat Transfer Properties • Decrease conduction from warm surfaces • Increase Convection • Increase Evaporation • Decrease Radiation Intake

  46. Tolerance Strategies: 1 (behavioral) Locate appropriate microclimate High evaporation Burrowing FIND SHADE!

  47. Tolerance Strategies: 1 Change Effective Surface Area Change Foraging strategy ants Change Color

  48. Tolerance Strategies: 2 (physiological) Vasodilation -promotes heat loss

  49. Even cicadas “sweat”! Tolerance Strategies: 2 (physiological) Vasodilation Evaporative heat loss • accelerated water loss for evaporative cooling at 41o C • replenish with plant juices

  50. Tolerance Strategies: 2 (physiological) Without rest, this rabbit will die of heat exhaustion, but the dog can keep on running… HOW?

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