Transcript Temperature

Abiotic Factors
• Resources
• Factors
– Abiotic parameters that
influence organism’s
distribution
Tolerance Range
• Biological processes
are sensitive to
environmental
conditions and can
only operate within
relatively narrow
ranges
Optimal Growth Temperatures
Microbial Activity
Temperature
• Temperature and moisture are the 2 most
limiting factors to the distribution of life on
earth
• In the universe temperature varies between
-273oC (absolute 0) and millions of degrees
Homeostasis
• Definition
• Mechanisms
Thermoneutral Zone
Thermoneutral Zones
Microclimates
• Macroclimate: Large scale weather
variation.
• Microclimate: Small scale weather
variation, usually measured over shorter
time period.
– Altitude
– Aspect
– Vegetation
• Ecologically important microclimates.
Microclimates
• Ground Color
– Darker colors absorb more visible light.
• Boulders / Burrows
– Create shaded, cooler environments.
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.
Plant Resources
•
•
•
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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
Plant distributions reflect the effects
of all resources
C3 species
C4 species
Highly sensitive to O2/ CO2
concentration. At low
CO2 levels absorbs O2
instead.
Not sensitive to O2/ CO2
concentration. Higher
affinity for CO2.
• Stomata
– Bring CO2 in
– Allow H2O to escape
Leaf Structure
• Top (e.g., trees)
– C3 leaves have chlorophyll
throughout the interior of the
leaf.
– CO2is found throughout the
leaf allowing the CO2 to escape
through open stomata
• Bottom (e.g., corn)
– C4 species has nearly all its
chlorophyll in two types of
cells which form concentric
cylinders around the fine veins
of the leaf.
– CO2 is concentrated in the
bundle-sheath cells and
isolated away from the stomata
C4 North American
Distribution
• Percentage of C4
species in the
grass floras of 32
regions in North
America (Teeri and
Stowe 1976)
C4 Australia Distribution
• Approximate
contour map of C4
native grasses in
Australia. Lines
give percentages of
C4 species in total
grass flora for 75
geographic regions
(Hattersley 1983).
Heat Exchange Pathways
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).
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.
• Thick pubescence increases leaf temperature
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
Temperature and Animal Performance
• Biomolecular Level
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: mechanisms allowing blood to flow
to coldest part of extremity without loss of heat; related to vasodilation/constriction
Countercurrent Heat Exchange
Temperature Regulation
Temperature Regulation by
Endothermic Animals
• Warming Insect Flight Muscles
– Bumblebees maintain temperature of thorax
between 30o and 37o C regardless of air
temperature
Temperature Regulation by
Endothermic Animals
• Warming Insect
Flight Muscles
– Sphinx moths
(Manduca
sexta) increase
thoracic
temperature
due to flight
activity
• Thermoregula
tes by
transferring
heat from the
thorax to the
abdomen
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
• Bergman’s Rule
• Allen’s Rule
Dormancy
• Diapause
– Pausing life at a
specific stage
Temp. Regulation
• Bergmann’s Rule
– Retains heat better
• Less surface area exposed to
outside environment
– Volume increases as cubed
power
•
Surface area increases
as a squared power
• Bergmann’s Rule
• Allen’s Rule
– Increases surface area
relative to volume
– Radiates heat better
Water Content of Air
• Total Atmospheric Pressure
– Pressure exerted by all gases in the air.
• Water Vapor Pressure
– Partial pressure due to water vapor.
• Saturation Water Vapor Pressure
– Pressure exerted by water vapor in air saturated
by water.
• Vapor Pressure Deficit
– Difference between WVP and SWVP at a
particular temperature.
Water Content of Air
• Relative Humidity:
Water Vapor Density
Saturation Water Vapor Density
(x 100)
• Water vapor density is measured as the water
vapor per unit volume of air
• Saturation water vapor density is measured as the
quantity of water vapor air can potentially hold
– Temperature dependent
Water Availability
• The tendency of water to move down
concentration gradients, and the magnitude
of those gradients, determine whether an
organism tends to lose or gain water from
its environment.
– Must consider an organism’s microclimate in
order to understand its water relations.
Water Content of Air
• Evaporation =
much of water lost
by terrestrial
organisms
– As water vapor in
the air ,water
concentration
gradient from
organisms to air is
reduced, thus
evaporative loss
– Evaporative coolers
work best in dry
climates
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: Diffusion of water through a semipermeable membrane.
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
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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
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Wia= Animal’s internal water
Wd = Drinking
Wf = Food
Wa = Absorbed by air
We = Evaporation
Ws = Secretion / Excretion
Water Acquisition by Plants
• Extent of plant root development often
reflects differences in water availability.
– Deeper roots often help plants in dry
environments extract water from deep within
the soil profile.
• Park found supportive evidence via studies
conducted on common Japanese grasses, Digitaria
adscendens and Eleusine indica.
Xerophyte adaptation – deep roots
•Chihuahuan Desert plants showing deep root systems
http://usda-ars.nmsu.edu/JER/Gibben4.gif
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 and Salt Balance in Aquatic
Environments
• Marine Fish and Invertebrates
– Isomotic organisms do not have to expend energy
overcoming osmotic gradient.
• Sharks, skates, rays - Elevate blood solute concentrations
hyperosmotic to seawater.
– Slowly gain water osmotically.
• Marine bony fish are strongly hypoosmotic, thus need to
drink seawater for salt influx.
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
• Saguaro Cactus
– Trunk / arms act as water storage organs.
– Dense network of shallow roots.
– Reduces evaporative loss.
•
Temperatures above thermoneutrality