Post on 11-Jan-2016
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 EACHTRAPEZIUM 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.
Yarrow (Achillea) along an altitudinal gradient
West East
Sierra-Nevada Range
Natural Selection
High temperatureHigh humidity
Low temperatureLow humidity Many
Generations
Cold genotype
Moderate genotype
Warm genotype
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 Transfer
• Htot= Hc ± Hr ± Hs - He
Htot = total metabolic heat
Hc = Conductive & convective
Hr = Radiative
Hs = Storage
He = evaporation
Heat Exchange Pathways
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 semi-permeable 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