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Temperature Relations

Chapter 4

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Microclimates

• Macroclimate: Large scale weather variation.• Microclimate: Small scale weather variation,

usually measured over shorter time period. Altitude

Higher altitude - lower temperature. Aspect

North-face shaded in Northern Hemisphere. Offers contrasting environments.

Vegetation Ecologically important microclimates.

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North

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Microclimates

• Ground Color Darker colors absorb more visible light.

• Boulders / Burrows Create shaded, cooler environments.

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Temperature Response of Metabolic Processes

• Enzymes: Optimum temperature. Multiples isozymes with different optima.

• Complex Processes: Photosynthetic optimal temperature. Acclimation within species (physiological)

• Whole organism: Cardinal temperatures (min, optimum, max) Bacteria to man.

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04_08.jpg

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Optimal Photosynthetic Temperatures

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Body Temperature Regulation

• Poikilotherms Body temperature varies directly with

environmental temperature.• Ectotherms

Rely mainly on external energy sources. Behavior and anatomical features used.

• Endotherms Rely heavily on metabolic energy.

Homeotherms maintain a relatively constant internal environment (birds and mammals)

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Balancing Heat Gain Against Heat Loss

• HS = Hm + Hcd + Hcv + Hr - He

HS = Total heat stored in an organism

Hm = Gained via metabolism

Hcd = Gained / lost via conduction

Hcv = Gained / lost via convection

Hr = Gained / lost via electromag. radiation

He = Lost via evaporation

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Heat Exchange Pathways

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Temperature Regulation by Plants (ectothermy)

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Temperature Regulation by Animals (ectothermy)

• Move to …. (e.g. Angilletta’s lizards)

• Pigmentation (e.g. Curruther’s grasshoppers)

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Temperature Regulation by Endothermic Animals

• Cooling: Anatomical features. Evaporative cooling.

• Thermal neutral zone is the range of environmental temperatures over which the metabolic rate of a homeothermic animal does not change. Breadth of TNZ varies among endotherms. Tropics narrow TNZ Polar broad TNZ

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Thermal Neutral Zones

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Endotherms 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

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Countercurrent Heat Exchange

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http://www.bio.davidson.edu/Courses/anphys/2000/CrawfordR/ccbloodflow.htm

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Temperature Regulation by Endothermic Animals

• Warming Insect Flight Muscles Bumblebees maintain temperature of

thorax between 30o and 37o C regardless of air temperature and flight activity.

Sphinx moths (Manduca sexta) increase thoracic temperature due to flight activity.

Thermoregulates by transferring heat from the thorax to the abdomen

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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.

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Eastern Skunk Cabbage

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Sources for images

• http://astrosun.tn.cornell.edu/~shami/smoky/lizard.jpg• http://www.sf.airnet.ne.jp/~yasuda/main/greenland/mo02.jpg• http://www.gotostcroix.com/hiking/images/cactus.jpg• http://wenlin.network.com.tw/goat/Old_Data/~english/alpine_plant/450/plant_29.

JPG• http://

www.americansouthwest.net/slot_canyons/photographs700/creosotebush.jpg• http://en.wikipedia.org/wiki/Image:Bumblebee_closeup_cropped.jpg