Abiotic Factors
• Resources
• Factors
Tolerance Range
• Homeostasis
Optimal Growth Temperatures
Microbial Activity
Temperature
Aquatic Temperatures
• Riparian vegetation influences stream temperature
by providing shade.
Homeostasis
• Definition
• Mechanisms
– Physiological
– Behavioral
Thermoneutral Zone
LETHAL TEMPERATURE RELATIONS FOR TWO
SPECIES OF FISH. ENCLOSED AREA OF EACH
TRAPEZIUM IS THE ZONE OF TOLERANCE
Thermoneutral Zones
Microclimates
• Macroclimate:
• Microclimate:
• Altitude
• Higher altitude - lower temperature.
– Aspect
• Offers contrasting environments.
– Vegetation
• Ecologically important microclimates.
Microclimates
• Ground Color
• Boulders / Burrows
Microclimate
• The distribution of species and temperature
contour maps do not always coincide
• This is because the temperatures organisms
experience are greatly effected by numerous
things.
– Behavior of animals
– North-facing & south-facing slopes
Plant Resources
•
•
•
•
Solar radiation (energy source)
Water
CO2
Minerals (nutrients)
Saguaro cactus (Cereus giganteus)
Distribution determined
by temp.
Limited by temperature
remaining below
freezing for 36 hr.
Dots are sites where temp.
remains below freezing for
36 hr. or more. “X’s” are
sites where these
conditions have not been
recorded. The dotted line is
the boundary of the
Sonoran desert.
Optimal Photosynthetic
Temperatures
• Stomata
– Bring CO2 in
– Allow H2O to escape
Heat Exchange Pathways
Temperature Regulation by
Plants
• Desert Plants: Must reduce heat storage.
– Hs = Hcd + Hcv + Hr
Temperature Regulation by
Plants
Temperature Regulation by
Plants
• Arctic and Alpine Plants
– Two main options to stay warm:
• Tropic Alpine Plants
– Rosette plants generally retain dead leaves,
which insulate and protect the stem from
freezing.
Sierra-Nevada Range
West
East
Yarrow (Achillea) along an altitudinal gradient
Natural Selection
Cold genotype
Moderate genotype
Warm genotype
Low temperature
Low humidity
Many
Generations
High temperature
High humidity
Animal Resources & Factors
•
•
•
•
•
Temperature
Oxygen, water
Nutrition (energy source)
Defense
Intraspecific competition
Temperature and Animal
Performance
• Biomolecular Level
– Most enzymes have rigid, predictable shape at
low temperatures
Heat Exchange Pathways
• Heat Transfer
• Htot= Hc ± Hr ± Hs - He
Htot = total metabolic heat
Hc = Conductive & convective
Hr = Radiative
Hs = Storage
He = evaporation
Body Temperature Regulation
• Poikilotherms
• Homeotherms
Body Temperature Regulation
• Poikilotherms
• Homeotherms
Body Temperature Regulation
• Ectotherms
• Endotherms
Temperature Regulation by
Ectothermic Animals
• Liolaemus Lizards
– Thrive in cold
environments
• Burrows
• Dark pigmentation
• Sun Basking
Temperature Regulation by
Ectothermic Animals
• Grasshoppers
– Some species adjust
for radiative heating
by varying intensity
of pigmentation
during development
Temp Regulation - costs
Temperature Regulation by
Endothermic Animals
• Regional
Heterothermy
Countercurrent heat exchange:
Countercurrent Heat Exchange
Temperature Regulation
rete mirabile
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
• Reduce Metabolic Rate
Adaptations to
Environmental
Extremes
• Dormancy
–
–
–
–
Diapause
Torpor
Hibernation
Estivation
• Bergman’s Rule
• Allen’s Rule
Dormancy
• Diapause
Temp. Regulation
• Bergmann’s Rule
– Retains heat better
• Bergmann’s Rule
• Allen’s Rule
Water Movement in Aquatic
Environments
• Water moves down concentration gradient
– freshwater vs. saltwater
• Aquatic organisms can be viewed as an
aqueous solution bounded by a semipermeable membrane floating in an another
aqueous solution
Water Movement in Aquatic
Environments
• If 2 environments differ in water or salt
concentrations, substances move down their
concentration gradients
– Diffusion
• Osmosis:
Water Movement in Aquatic
Environment
• Isomotic:
– [Salt]
– body fluids = external fluid
• Hypoosmotic:
– [Salt] <
– body fluids > external fluid
– Water moves out
• Hyperosmotic:
– [Salt] >
– body fluids < external fluids
– Water moves in
Water Regulation on Land
• Terrestrial organisms face (2) major
challenges:
– Evaporative loss to environment.
– Reduced access to replacement water.
Water Regulation on Land Plants
Water Regulation on Land Plants
• Wip= Wr + Wa - Wt - Ws
•
•
•
•
•
Wip= Plant’s internal water
Wr =Roots
Wa = Air
Wt = Transpiration
Ws = Secretions
Water Regulation on Land Animals
Water Regulation on Land Animals
• Wia= Wd + Wf + Wa - We - Ws
•
•
•
•
•
•
Wia= Animal’s internal water
Wd = Drinking
Wf = Food
Wa = Absorbed by air
We = Evaporation
Ws = Secretion / Excretion
Water Acquisition by Animals
• Most terrestrial animals satisfy their water
needs via eating and drinking.
– Can also be gained via metabolism through
oxidation of glucose:
• C6H12O6 + 6O2  6CO2 + 6H2O
– Metabolic water refers to the water released during
cellular respiration.
Water Conservation by Plants and
Animals
• Many terrestrial organisms equipped with
waterproof outer covering.
• Concentrated urine / feces.
• Condensing water vapor in breath.
• Behavioral modifications to avoid stress
times.
• Drop leaves in response to drought.
• Thick leaves
• Few stomata
• Periodic dormancy
Figure 3.17
Kangaroo rat,
in SW USA,
forages for
food at night;
benefit of
cooler air
temps. Water
conserved via
condensation
in large nasal
passages and
lungs.
Loop of Henle in mammal kidney
Dissimilar Organisms with
Similar Approaches to Desert
Life
• Camels
– Can withstand water loss up to 20%.
• Face into sun to reduce exposure.
• Thick hair: Increased body temperature lowers heat
gradient.
• Saguaro Cactus
– Trunk / arms act as water storage organs.
– Dense network of shallow roots.
– Reduces evaporative loss.
•
Temperatures above thermoneutrality
– Become hyperthermic by raising TB to near TA, thereby
reducing water loss and continuing dry heat transfer
•
e.g., many desert mammals
Readings
•
•
•
•
•
Ecological Issues (EI): Urban Microclimates, p. 34
EI – Groundwater Resources, p.39
Quantifying Ecology 4.1, pp.59-60
Field Studies – Kaoru Kitajima, pp. 112-113
Quantifying Ecology 7.1, pp. 140-141