Temperature Relations

—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 micro climates.

—Ground Color

—Darker colors absorb more visible light.

—Boulders  / Burrows

—Create shaded, cooler environments.

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

Temperature and Animal Performance

 

—Bio-molecular 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).

Extreme Temperatures and Photosynthesis

—Photosynthesis

—6CO2 + 12H2O à C6H12O6 + 6O2 + 6H20

—Extreme temperatures usually reduce rate of photosynthesis.

—Different plants have different optimal temperatures.

—Acclimation : Physiological changes in response to temperature.

—Acclimatization

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.

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

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.

 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).

 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.

 Temperature Regulation by Ectothermic Animals

—Liolaemus Lizards

—Thrive in cold environments.

—Burrows

—Dark pigmentation

—Sun Basking

—Grasshoppers

—Some species can adjust for radiative heating by varying intensity of pigmentation during development.

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.

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

 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.

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