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Explore the impact of temperature on metabolic processes, body temperature regulation, and heat exchange in organisms. Learn how plants and animals adapt to varying temperatures and regulate their internal environment.
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Temperature Relations Chapter 4
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.
Microclimates • Ground Color • Darker colors absorb more visible light. • Boulders / Burrows • Create shaded, cooler environments.
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.
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)
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
Temperature Regulation by Animals (ectothermy) • Move to …. (e.g. Angilletta’s lizards) • Pigmentation (e.g. Curruther’s grasshoppers)
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
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
http://www.bio.davidson.edu/Courses/anphys/2000/CrawfordR/ccbloodflow.htmhttp://www.bio.davidson.edu/Courses/anphys/2000/CrawfordR/ccbloodflow.htm
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
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.
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