11

Temperature RelationsChapter 4

22

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

33

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.

44

Microclimates Ground Color

Darker colors absorb more visible light. Boulders / Burrows

Create shaded, cooler environments.

55

Aquatic Temperatures Specific Heat

Absorbs heat without changing temperature. 1 cal energy to heat 1 cm3 of water 1o 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.

Riparian Areas

66

Aquatic Temperatures Riparian vegetation influences stream

temperature by providing shade.

77

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).

88

Extreme Temperatures and Photosynthesis

Photosynthesis

6CO2 + 12H2O C6H12O6 + 6CO2 + 6H20

Extreme temperatures usually reduce rate of photosynthesis. Different plants have different optimal temperatures. Acclimation: Physiological changes in response to

temperature.

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Optimal Photosynthetic Temperatures

1010

Temperature and Microbial Activity Morita studied the effect of temperature on

population growth among psychrophilic marine bacteria around Antarctica. Grew fastest at 4o C. Some growth recorded in temperatures as cold

as - 5.5o C. Some thermophilic microbes have been

found to grow best in temperatures as hot as 110o C.

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Optimal Growth Temperatures

1212

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

1313

Heat Exchange Pathways

1414

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.

1515

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).

HS = Total heat stored in an organismHm = Gained via metabolismHcd = Gained / lost via conductionHcv = Gained / lost via convectionHr = Gained / lost via electromag. radiationHe = Lost via evaporation

1616

Temperature Regulation by Plants

1717

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. Thick pubescence increases leaf temperature.

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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.

1919

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.

2020

Thermal Neutral Zones

2121

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.

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Countercurrent Heat Exchange

2323

Temperature Regulation by Endothermic Animals

Warming Insect Flight Muscles Bumblebees maintain temperature of thorax

between 30o and 37o 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

2424

Moth Circulation and Thermoregulation

2525

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.

2626

Eastern Skunk Cabbage

2727

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

2828

Review

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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