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Temperature Relations Chapter 5 1 Co 5 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 Surviving Extreme Temperatures 3 Figure 05_01 4 Microclimates • • Macroclimate (大氣候): Large scale weather variation. Microclimate (微氣候): climatic variation on a scale of few kilometers, meters, or even centimeters, usually measured over short periods of time. Altitude Higher altitude - lower temperature. Aspect Offers contrasting environments. Vegetation Ecologically important microclimates. 5 6 Microclimates • • Ground Color Darker colors absorb more visible light. Boulders / Burrows Create shaded, cooler environments. 7 8 9 10 Figure 05_06 11 Aquatic Temperatures • • • • Specific Heat Absorbs heat without changing temperature. 3 o 1 cal energy to heat 1 cm of water 1 C. Air - .0003 cal Latent Heat of Evaporation o About 584 cal per gram of water at 22 C and 580 cal per gram of water at 35 oC. Latent Heat of Fusion 1 g of water gives off 80 cal as it freezes. Riparian Areas 12 Aquatic Temperatures • Riparian vegetation influences stream temperature by providing shade. 13 14 5.2 Evolutionary Trade-offs • Organisms allocate limited energy to a certain function which then reduces the amount for other functions. This trade-off (交換) in energy allocation (配置) will differ among environments with functions that include growth, reproduction, and defense against predators 15 The Principle of Allocation • • Levins concluded that the evolutionary consequences of this trade-off results in populations having high fitness (適當) 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. 16 The Principle of Allocation 17 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). 18 19 20 21 Figure 05_10 22 Extreme Temperatures and Photosynthesis • Photosynthesis 6CO2 + 12H2O C6H12O6 + 6CO2 + 6H20 Extreme temperatures usually reduce rate of photosynthesis. Different plants have different optimal temperatures. Acclimation (馴化): Physiological changes in response to temperature. 23 Figure 05_11 24 Optimal Photosynthetic Temperatures 25 Temperature and Microbial Activity • • Morita studied the effect of temperature on population growth among psychrophilic (嗜冷 性的) marine bacteria around Antarctica. o Grew fastest at 4 C. Some growth recorded in temperatures as cold as - 5.5o C. Some thermophilic (嗜熱性的)microbes have been found to grow best in temperatures as hot as 110o C. 26 Optimal Growth Temperatures 27 Optimal Growth Temperatures Antarctic bacteria 28 Optimal Growth Temperatures Hot spring microbes 29 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 30 Heat Exchange Pathways 31 Body Temperature Regulation • • • Poikilotherms (變溫動物) Body temperature varies directly with environmental temperature. Ectotherms (外溫動物) Rely mainly on external energy sources. Endotherms (內溫動物) Rely heavily on metabolic energy. Homeotherms (恒溫動物) maintain a relatively constant internal environment. 32 Temperature Regulation by Plants • Desert Plants: Must reduce heat storage. Hs = Hcd Hcv Hr To avoid heating, plants have (3) options: Decrease heating via conduction (Hcd). Increase conductive cooling (Hcv). Reduce radiative heating (Hr). Leaves with a dense coating of white plant hairs. 33 Temperature Regulation by Plants 34 北極與高山植物的平鋪生長植物 35 Temperature Regulation by Plants • • Arctic and Alpine Plants Two main options to stay warm: Increase radiative heating (Hr). Decrease Convective Cooling (Hcv). Tropic Alpine Plants Rosette plants generally retain dead leaves, which insulate and protect the stem from freezing. (蓮座型植物) Thick pubescence increases leaf temperature. (軟毛) 36 37 38 A cushion plant 39 柳樹 40 Temperature Regulation by Ectothermic Animals • • Eastern Fence Lizard (Sceloporus undulatus) 東方強稜蜥 Metabolizable energy intake maximized at 33ºC Preferred temperature closely matches the temperature at which metabolizable energy intake is maximized Grasshoppers (透翅蝗) Some species can adjust for radiative heating by varying intensity of pigmentation during development. 41 Figure 05_20 42 撫養 43 44 高溫抑制食蟲菌 45 46 Temperature Regulation by Endothermic Animals • Thermal neutral zone (熱中性區) is the range of environmental temperatures over which the metabolic rate of a homeothermic animal does not change. Breadth varies among endothermic species. 47 Thermal Neutral Zones 樹懶 絨猴 松鼠 幼仔 48 Temperature Regulation by Endothermic Animals • Swimming Muscles of Large Marine Fish Lateral swimming muscles of many fish (Mackerel Sharks 灰鯖鯊, Tuna 鮪魚) are well supplied with blood vessels that function as countercurrent heatexchangers. Keep body temperature above that of surrounding water. 49 Countercurrent Heat Exchange 50 Countercurrent Heat Exchange 藍鰭鮪魚 皮膚的 51 52 Temperature Regulation by Endothermic Animals • Warming Insect Flight Muscles Bumblebees (雄蜂) maintain temperature of thorax (胸甲) between 30o and 37o C regardless of air temperature. Sphinx moths 天蛾科 (Manduca sexta) increase thoracic temperature due to flight activity. Thermoregulates by transferring heat from the thorax to the abdomen 53 Moth Circulation and Thermoregulation 54 Temperature Regulation by Thermogenic Plants • Almost all plants are poikilothermic (變溫的) ectotherms (外溫生物). Plants in family Araceae use metabolic energy to heat flowers (天南星科). Skunk Cabbage (Symplocarpus foetidus 臭菘) stores large quantities of starch in large root, and then translocate it to the inflorescence (花序) where it is metabolized thus generating heat. 55 Eastern Skunk Cabbage (臭菘) 肉 穗 花 序 主根 56 57 虎甲蟲 58 棲息 59 Surviving Extreme Temperatures • • Inactivity Seek shelter during extreme periods. Reducing Metabolic Rate Hummingbirds enter a state of torpor (蟄 伏) when food is scarce and night temps are extreme. Hibernation (冬眠) - Winter Estivation (夏眠) - Summer 60 61 62