This is about the temperature in nature

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Temperature Relations
Chapter 4

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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

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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.

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Microclimates
 Ground Color
 Darker colors absorb more visible light.
 Boulders / Burrows
 Create shaded, cooler environments.

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Aquatic Temperatures
 Riparian vegetation influences stream
temperature by providing shade.

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Temperature and Animal Performance
 Biomolecular Level
 Most enzymes have rigid, predictable shape at
low temperatures

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Extreme Temperatures and
Photosynthesis
 Photosynthesis
6CO2 + 12H2O  C6H12O6 + 6CO2 + 6H20
 Extreme temperatures usually reduce rate of
photosynthesis.

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Optimal Photosynthetic Temperatures

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Temperature and Microbial Activity
 Morita studied the effect of
temperature on population
growth among 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

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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

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Heat Exchange Pathways

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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.

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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 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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Temperature Regulation by Plants

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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
 Grasshoppers
 Some species can adjust for radiative heating by
varying intensity of pigmentation during
development.

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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.

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Thermal Neutral Zones

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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

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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

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Moth Circulation and Thermoregulation

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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.

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Eastern Skunk Cabbage

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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

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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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