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Temperature relations
Outline
Microclimate
Ecological “laws” for individuals
Temperature optima of organisms
Temperature regulation by plants and
animals
Hot enough for you?
Microclimates
Physiological ecology
What environmental conditions
are most important for organisms?
AKA ecophysiology
How individual organisms respond to
the abiotic environment:
Temperature
Water
 Light
 Nutrients


Northern pitcher plant
Ellison et al. (2003)
Ecological “laws” (1)
Underlying mechanism
So, how do individual organisms respond to
their environment ultimately?
“Nothing in biology makes sense except
in the light of evolution.”The American Biology Teacher (1973)

“The Big Four”
Describing how individual organisms
interact with their environment

Theodosius Dobzhansky (1900 – 1975)
Law of the minimum (von Liebig):



Always the same?
Co-limitation?
Law of limiting factors (Blackman):
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Ecological “laws” (2)
Ecological “laws” (3)
Law of tolerance (Shelford)
Take-home messages:

Life is a compromise
Can you be adapted to all
environmental conditions?
 Once you have maximum fitness
under one set of conditions, what
does that mean if the environment
changes or if you move?

Victor Shelford

Many species can co-exist in the
same region by specializing in
different conditions
Trout and an enzyme
Life and temperature
Life requires a certain temperature (or range
of temperatures) for optimal metabolism
Do trout show an optimum temperature for activity?
Acetylcholinesterase activity
Cold environments & metabolic rate: prediction?
Hot environments & metabolic rate?
 Why?
 Overall result?


Rainbow trout have
2 forms of this enzyme
Why these 2
temperatures?
Fig. 5.8
Plants and temperature optima
*
Shorter-term adjustments to
environmental changes
These last examples show natural selection
selects for genetically-determined traits that
allow the organism to be adapted
physiologically to its environment
But, can an organism show shorter-term
adjustments to changes in temperature
(within certain evolutionary-set bounds) that
allow it to be successful?
Pleurozium
schreberi

Atriplex lentiformis

Acclimation
Temperature regulation
Fig. 5.11
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Temperature regulation
Acclimation by desert shrubs
An evergreen shrub
Winter temps
Summer temps
All experimental shrubs
were grown from cuttings;
so, we do not have to
worry about differences
due to?
Organisms must balance gains
and losses of heat energy
Direction of heat transfer?
Types of heat transfer
 Sunlight (short-wave radiation)
 Long-wave infrared radiation
from objects
 Metabolism
 Evaporation
 Conduction
 Convection
Fig. 5.12
Global heat transfers
Desert plants & heat
Jojoba
Brittlebush
National Park Service
Also see
Fig. 5.16
Types of physiological groupings
Internal temperature
Ectotherms
Endotherms
Heterotherms
Creosote bush
Ectotherms (1)
Characteristics


High thermal conductance
Low metabolic rate
Metabolic rate increases
? with increasing
temperatures
Fig. 5.9: Eastern fence lizard
External temperature
*
Schmidt-Nielsen 1997
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Ectotherms (2)
Ectotherms (3)
Q10
 Q10
How do you regulate your temperature in more
extreme conditions that last a long time?
Diapause
= RT / RT-10
Where RT = the rate at any given body
temperature T
 RT-10 = rate at body temperature T – 10ºC


Typically Q10’s are around 2, which means?
Usually genetically determined and timed by
various environmental cues (e.g., light and
temperature)
Red-legged
earth mite
Rostgaard & Jacobsen 2005
Diapausing eggs
Invasive crop
pest down under
Endotherms
Heterotherms (1)
Fig. 5.25
Roach
Hawkmoth
Heterotherms (3)
Heterotherms (2)
Desert tortoise
Uses 90%
less energy
Fig. 5.32
Dormouse
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