1. 1 Temperature Relations Chapter 4

2. 2 Outline Microclimates Aquatic Temperatures Temperature and Animal Performance Extreme Temperature and Photosynthesis Temperature and Microbial Activity Balancing Heat Gain Against Heat Loss Body Temperature Regulation  Plants  Ectothermic Animals  Endothermic Animals

3. 3 Microclimates Macroclimate: Large scale weather variation. Microclimate: Small scale weather variation, usually measured over shorter time period.  Altitude  Higher altitude - lower temperature.  Aspect  Offers contrasting environments.  Vegetation  Ecologically important microclimates.

4. 4 Microclimates Ground Color  Darker colors absorb more visible light. Boulders / Burrows  Create shaded, cooler environments.

5. 5 Aquatic Temperatures Specific Heat  Absorbs heat without changing temperature.  1 cal energy to heat 1 cm 3 of water 1 o C.  Air -.0003 cal Latent Heat of Evaporation  1 cal can cool 580 g of water. Latent Heat of Fusion  1 g of water gives off 80 cal as it freezes. Riparian Areas

6. 6 Aquatic Temperatures Riparian vegetation influences stream temperature by providing shade.

7. 7 Temperature and Animal Performance Biomolecular Level  Most enzymes have rigid, predictable shape at low temperatures  Low temperatures cause low reaction rates, while excessively high temperatures destroy the shape.  Baldwin and Hochachka studied the influence of temperature on performance of acetylcholinesterase in rainbow trout (Oncorhynchus mykiss).

8. 8 Extreme Temperatures and Photosynthesis Photosynthesis 6CO 2 + 12H 2 O  C 6 H 12 O 6 + 6CO 2 + 6H 2 0  Extreme temperatures usually reduce rate of photosynthesis.  Different plants have different optimal temperatures.  Acclimation: Physiological changes in response to temperature.

9. 9 Optimal Photosynthetic Temperatures

10. 10 Temperature and Microbial Activity Morita studied the effect of temperature on population growth among psychrophilic marine bacteria around Antarctica.  Grew fastest at 4 o C.  Some growth recorded in temperatures as cold as - 5.5 o C. Some thermophilic microbes have been found to grow best in temperatures as hot as 110 o C.

11. 11 Optimal Growth Temperatures

12. 12 Balancing Heat Gain Against Heat Loss H S = H m + H cd + H cv + H r - H e  H S = Total heat stored in an organism  H m = Gained via metabolism  H cd = Gained / lost via conduction  H cv = Gained / lost via convection  H r = Gained / lost via electromag. radiation  H e = Lost via evaporation

13. 13 Heat Exchange Pathways

14. 14 Body Temperature Regulation Poikilotherms  Body temperature varies directly with environmental temperature. Ectotherms  Rely mainly on external energy sources. Endotherms  Rely heavily on metabolic energy.  Homeotherms maintain a relatively constant internal environment.

15. 15 Temperature Regulation by Plants Desert Plants: Must reduce heat storage.  H s = H cd + H cv + H r  To avoid heating, plants have (3) options:  Decrease heating via conduction (H cd ).  Increase conductive cooling (H cv ).  Reduce radiative heating (H r ).

16. 16 Temperature Regulation by Plants

17. 17 Temperature Regulation by Plants Arctic and Alpine Plants  Two main options to stay warm:  Increase radiative heating (H r ).  Decrease Convective Cooling (H cv ). Tropic Alpine Plants  Rosette plants generally retain dead leaves, which insulate and protect the stem from freezing.  Thick pubescence increases leaf temperature.

18. 18 Temperature Regulation by Ectothermic Animals Liolaemus Lizards  Thrive in cold environments.  Burrows  Dark pigmentation  Sun Basking Grasshoppers  Some species can adjust for radiative heating by varying intensity of pigmentation during development.

19. 19 Temperature Regulation by Endothermic Animals Thermal neutral zone is the range of environmental temperatures over which the metabolic rate of a homeothermic animal does not change.  Breadth varies among endothermic species.

20. 20 Thermal Neutral Zones

21. 21 Temperature Regulation by Endothermic Animals Swimming Muscles of Large Marine Fish  Lateral swimming muscles of many fish (Mackerel, Sharks, Tuna) are well supplied with blood vessels that function as countercurrent heat-exchangers.  Keep body temperature above that of surrounding water.

22. 22 Countercurrent Heat Exchange

23. 23 Temperature Regulation by Endothermic Animals Warming Insect Flight Muscles  Bumblebees maintain temperature of thorax between 30 o and 37 o C regardless of air temperature.  Sphinx moths (Manduca sexta) increase thoracic temperature due to flight activity.  Thermoregulates by transferring heat from the thorax to the abdomen

24. 24 Moth Circulation and Thermoregulation

25. 25 Temperature Regulation by Thermogenic Plants Almost all plants are poikilothermic ectotherms.  Plants in family Araceae use metabolic energy to heat flowers.  Skunk Cabbage (Symplocarpus foetidus) stores large quantities of starch in large root, and then translocate it to the inflorescence where it is metabolized thus generating heat.

26. 26 Eastern Skunk Cabbage

27. 27 Surviving Extreme Temperatures Inactivity  Seek shelter during extreme periods. Reducing Metabolic Rate  Hummingbirds enter a state of torpor when food is scarce and night temps are extreme.  Hibernation - Winter  Estivation - Summer

28. 28 Review Microclimates Aquatic Temperatures Temperature and Animal Performance Extreme Temperature and Photosynthesis Temperature and Microbial Activity Balancing Heat Gain Against Heat Loss Body Temperature Regulation  Plants  Ectothermic Animals  Endothermic Animals

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