1. Abiotic Factors Resources Factors –Abiotic parameters that influence organism’s distribution

2. Tolerance Range Biological processes are sensitive to environmental conditions and can only operate within relatively narrow ranges

3. Optimal Growth Temperatures Microbial Activity

4. Temperature Temperature and moisture are the 2 most limiting factors to the distribution of life on earth In the universe temperature varies between -273 o C (absolute 0) and millions of degrees

5. Homeostasis Definition Mechanisms

6. Thermoneutral Zone

7. Thermoneutral Zones

8. Microclimates Macroclimate: Large scale weather variation. Microclimate: Small scale weather variation, usually measured over shorter time period. –Altitude –Aspect –Vegetation Ecologically important microclimates.

9. Microclimates Ground Color –Darker colors absorb more visible light. Boulders / Burrows –Create shaded, cooler environments.

10. 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.

11. Plant Resources Solar radiation (energy source) Water CO 2 Minerals (nutrients)

12. 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.

13. Optimal Photosynthetic Temperatures

14. Plant distributions reflect the effects of all resources C 3 species C 4 species Highly sensitive to O 2 / CO 2 concentration. At low CO 2 levels absorbs O 2 instead. Not sensitive to O 2 / CO 2 concentration. Higher affinity for CO 2.

15. Stomata –Bring CO 2 in –Allow H 2 O to escape

16. Leaf Structure Top (e.g., trees) –C 3 leaves have chlorophyll throughout the interior of the leaf. –CO 2 is found throughout the leaf allowing the CO 2 to escape through open stomata Bottom (e.g., corn) –C 4 species has nearly all its chlorophyll in two types of cells which form concentric cylinders around the fine veins of the leaf. –CO 2 is concentrated in the bundle-sheath cells and isolated away from the stomata

17. C 4 North American Distribution Percentage of C 4 species in the grass floras of 32 regions in North America (Teeri and Stowe 1976)

18. C 4 Australia Distribution Approximate contour map of C 4 native grasses in Australia. Lines give percentages of C 4 species in total grass flora for 75 geographic regions (Hattersley 1983).

19. Heat Exchange Pathways

20. Temperature Regulation by Plants Desert Plants: Must reduce heat storage. –H s = H cd + H cv + H r –To avoid heating, plants have (3) options: Decrease heating via conduction (H cd ). Increase conductive cooling (H cv ). Reduce radiative heating (H r ).

21. Temperature Regulation by Plants

22. 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

24. Yarrow (Achillea) along an altitudinal gradient WestEast Sierra-Nevada Range

25. Natural Selection High temperature High humidity Low temperature Low humidity Many Generations Cold genotype Moderate genotype Warm genotype

26. Animal Resources & Factors Temperature Oxygen, water Nutrition (energy source) Defense

27. Temperature and Animal Performance Biomolecular Level

28. 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

29. Body Temperature Regulation Poikilotherms Homeotherms

30. Body Temperature Regulation Poikilotherms Homeotherms

31. Body Temperature Regulation Ectotherms Endotherms

32. Temperature Regulation by Ectothermic Animals Liolaemus Lizards –Thrive in cold environments Burrows Dark pigmentation Sun Basking

33. Temperature Regulation by Ectothermic Animals Grasshoppers –Some species adjust for radiative heating by varying intensity of pigmentation during development

34. Temp Regulation - costs

35. Temperature Regulation by Endothermic Animals Regional Heterothermy

36. Countercurrent heat exchange: mechanisms allowing blood to flow to coldest part of extremity without loss of heat; related to vaso- dilation/constriction

37. Countercurrent Heat Exchange

39. Temperature Regulation

41. Temperature Regulation by Endothermic Animals Warming Insect Flight Muscles –Bumblebees maintain temperature of thorax between 30 o and 37 o C regardless of air temperature

42. 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

43. 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

44. Surviving Extreme Temperatures Inactivity Reduce Metabolic Rate

45. Adaptations to Environmental Extremes Dormancy Bergman’s Rule Allen’s Rule

46. Dormancy Diapause –Pausing life at a specific stage

49. Temp. Regulation

50. 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

51. Bergmann’s Rule

52. Allen’s Rule –Increases surface area relative to volume –Radiates heat better

53. 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.

54. 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

55. 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.

56. 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

57. 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

58. 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 semi- permeable membrane.

59. 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

60. Water Regulation on Land Terrestrial organisms face (2) major challenges: –Evaporative loss to environment. –Reduced access to replacement water.

61. Water Regulation on Land - Plants

62. 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

63. Water Regulation on Land - Animals

64. 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

65. 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.

66. Xerophyte adaptation – deep roots http://usda-ars.nmsu.edu/JER/Gibben4.gif Chihuahuan Desert plants showing deep root systems

67. 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.

68. 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.

69. 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

70. 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.

71. Loop of Henle in mammal kidney

72. 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.

74. Temperatures above thermoneutrality