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 CO 2 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 CO 2 in –Allow H 2 O to escape

Heat Exchange Pathways

Temperature Regulation by Plants Desert Plants: Must reduce heat storage. –H s = H cd + H cv + H r

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 WestEast Sierra-Nevada Range

Natural Selection High temperature High humidity Low temperature Low 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 H tot = H c ± H r ± H s - H e H tot = total metabolic heat H c = Conductive & convective H r = Radiative H s = Storage H e = 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

W ip = W r + W a - W t - W s W ip = Plant’s internal water W r =Roots W a = Air W t = Transpiration W s = Secretions

Water Regulation on Land - Animals

W ia = W d + W f + W a - W e - W s W ia = Animal’s internal water W d = Drinking W f = Food W a = Absorbed by air W e = Evaporation W s = 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: C 6 H 12 O 6 + 6O 2  6CO 2 + 6H 2 O –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 T B to near T A, 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 Field Studies – Kaoru Kitajima, pp Quantifying Ecology 7.1, pp