Temperature Relations
Chapter 5
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Co 5
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Outline
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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
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Figure 05_01
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Microclimates
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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.
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Microclimates
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Ground Color

Darker colors absorb more visible light.
Boulders / Burrows

Create shaded, cooler environments.
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Figure 05_06
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Aquatic Temperatures
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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

About 584 cal per gram of water at 22 o C and 580 cal per gram of water at 35 o C.
Latent Heat of Fusion

1 g of water gives off 80 cal as it freezes.
Riparian Areas
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Aquatic Temperatures
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Riparian vegetation influences stream temperature by providing shade.
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5.2 Evolutionary Trade-offs
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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
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The Principle of Allocation
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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.
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The Principle of Allocation
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Temperature and Animal Performance
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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 ).
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Figure 05_10
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Extreme Temperatures and Photosynthesis
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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.

Acclim a tion ( 馴化 ): Physiol o gical changes in response to temperature.
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Figure 05_11
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Optimal Photosynthetic Temperatures
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Temperature and Microbial Activity
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Morita studied the effect of temperature on population growth among psychrophilic ( 嗜冷
性的 ) marine bacteria around Antarctica.

Grew fastest at 4 o C.

Some growth recorded in temperatures as cold as 5.5
o C.
Some thermophilic （嗜熱性的） microbes have been found to grow best in temperatures as hot as 110 o C.
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Optimal Growth Temperatures
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Optimal Growth Temperatures
Antarctic bacteria
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Optimal Growth Temperatures
Hot spring microbes
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Balancing Heat Gain Against Heat Loss
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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
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Heat Exchange Pathways
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Body Temperature Regulation
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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.
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Temperature Regulation by Plants
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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
).
Leaves with a dense coating of white plant hairs.
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Temperature Regulation by Plants
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北極與高山植物的平鋪生長植物
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Temperature Regulation by Plants
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Arctic and Alpine Plants

Two main options to stay warm:


Increase r a diative heating (H r
).
Decrease Convective Cooling (H cv
).
Tropic Alpine Plants

Ros e tte plants generally retain dead leaves, which insulate and protect the stem from freezing. (蓮座型植物)

Thick pub e scence increases leaf temperature. (軟毛)
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A cushion plant
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柳樹
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Temperature Regulation by Ectothermic Animals
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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.
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Figure 05_20
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撫養
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高溫抑制食蟲菌
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Temperature Regulation by Endothermic Animals
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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.
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Thermal Neutral Zones
樹懶
幼仔
松鼠
絨猴
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Temperature Regulation by Endothermic Animals
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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.
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Countercurrent Heat Exchange
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Countercurrent Heat Exchange
藍鰭鮪魚
皮膚的
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Temperature Regulation by Endothermic Animals
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Warming Insect Flight Muscles

Bumblebees ( 雄蜂 ) maintain temperature of thorax ( 胸甲 ) between 30 o and 37 o 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
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Moth Circulation and Thermoregulation
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Temperature Regulation by Thermogenic Plants
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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 inflor e scence (花序) where it is metabolized thus generating heat.
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Eastern Skunk Cabbage (臭菘)
肉
穗
花
序
主根
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虎甲蟲
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棲息
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Surviving Extreme Temperatures
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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
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