Temperature Relations
Chapter 4
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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
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Microclimates
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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.
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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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Aquatic Temperatures
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Specific Heat
 Absorbs heat without changing
temperature.
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o
 1 cal energy to heat 1 cm of water 1 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
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Aquatic Temperatures
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Riparian vegetation influences stream
temperature by providing shade.
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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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Extreme Temperatures and Photosynthesis
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Photosynthesis
6CO2 + 12H2O  C6H12O6 + 6CO2 + 6H20
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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
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Temperature and Microbial Activity
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Morita studied the effect of temperature on
population growth among psychrophilic
marine bacteria around Antarctica.
o
 Grew fastest at 4 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
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Balancing Heat Gain Against Heat Loss
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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
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Heat Exchange Pathways
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Body Temperature Regulation
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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.
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Temperature Regulation by Plants
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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).
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Temperature Regulation by Plants
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Temperature Regulation by Plants
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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
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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.
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Temperature Regulation by Endothermic Animals
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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.
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Thermal Neutral Zones
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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, 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
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Temperature Regulation by Endothermic Animals
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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
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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
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.
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Eastern Skunk Cabbage
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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
when food is scarce and night temps are
extreme.
 Hibernation - Winter
 Estivation - Summer
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Review
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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
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