9/1/11
Ecology (BIOL 250) Lecture 4: Temperature Regulation
Today s Outline
Announcements
∞  Environmental Studies
minor
icroclimates
M
Aquatic Temperatures
Temperature and Animal Performance
Extreme Temperature and Photosynthesis
Balancing Heat Gain Against Heat Loss
Body Temperature Regulation
Plants
Ectothermic Animals
Endothermic Animals
adaptations
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Microclimates
 Macroclimate: Large scale weather variation.
 Microclimate: Small scale weather variation,
usually measured over shorter time period.
 Altitude
 Aspect
 Vegetation
 Ecologically important microclimates.
Extreme Temperatures and
Photosynthesis
Microclimates
 Ground Color
 Darker colors absorb more visible light.
 Photosynthesis
 Boulders / Burrows
 Create shaded, cooler environments.
Aquatic Temperatures
 Riparian vegetation influences stream temperature by
providing shade.
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.
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 radiation
 He = Lost via evaporation
Body Temperature Regulation
 Ectotherms
   Endotherms
   Homeotherms

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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 convective cooling (Hcv).
 Reduce radiative heating (Hr).
Temperature Regulation by Ectothermic Animals
Temperature Regulation by Plants
 Arctic and Alpine Plants
  Two main options to stay warm:
 Increase radiative heating (Hr).
 Decrease Convective Cooling (Hcv).
Temperature Regulation by Ectothermic Animals
 Grasshoppers
 Liolaemus Lizards
 Thrive in cold environments.
 Burrows
 Dark pigmentation  Sun Basking
Temperature Regulation by Endothermic Animals
 Thermoneutral zone is the range of
environmental temperatures over which the
metabolic rate of a homeothermic animal does
not change.
 Some species can adjust for radiative heating by
varying intensity of pigmentation during
development.
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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Temperature Regulation by Heterothermic 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
Eastern Skunk Cabbage
(Symplocarpus foetidus)
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
Eastern Skunk Cabbage
(Symplocarpus foetidus)
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