1. 1 Temperature Relations Chapter 5 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

2. 2 Outline Microclimates Aquatic Temperatures The Principle of Allocation Temperature and Animal Performance Extreme Temperature and Photosynthesis Temperature and Microbial Activity Balancing Heat Gain Against Heat Loss Body Temperature Regulation Surviving Extreme Temperatures

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.

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

7. 7 The Principle of Allocation Organisms allocate limited energy to a certain function which then reduces the amount for other functions.  This trade-off in energy allocation will differ among environments with functions that include growth, reproduction, and defense against predators

8. 8 The Principle of Allocation Levins concluded that the evolutionary consequences of this trade-off results in populations having high fitness in one environment, but lowered fitness in another environment. Bennett and Lenski found support for Levins’ Principle of Allocation using experiments with Escherichia coli grown in different temperature environments.

9. 9 The Principle of Allocation

10. 10 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).

11. 11 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.

12. 12 Optimal Photosynthetic Temperatures

13. 13 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.

14. 14 Optimal Growth Temperatures

15. 15 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

16. 16 Heat Exchange Pathways

17. 17 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.

18. 18 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 ).

19. 19 Temperature Regulation by Plants

20. 20 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.

21. 21 Temperature Regulation by Ectothermic Animals Eastern Fence Lizard ( Sceloporus undulatus )  Metabolizable energy intake maximized at 33ºC  Preferred temperature closely matches the temperature at which metabolizable energy intake is maximized Grasshoppers  Some species can adjust for radiative heating by varying intensity of pigmentation during development.

22. 22 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.

23. 23 Thermal Neutral Zones

24. 24 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.

25. 25 Countercurrent Heat Exchange

26. 26 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

27. 27 Moth Circulation and Thermoregulation

28. 28 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.

29. 29 Eastern Skunk Cabbage

30. 30 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

31. 31 Review Microclimates Aquatic Temperatures The Principle of Allocation Temperature and Animal Performance Extreme Temperature and Photosynthesis Temperature and Microbial Activity Balancing Heat Gain Against Heat Loss Body Temperature Regulation Surviving Extreme Temperatures

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