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Environmental Adaptations

Mammalogy (Fall 2013 Althoff - reference FDVM Chapter 9). LEC 10B. Environmental Adaptations. Which is it for Mammals ?. Warm-bloodied ? – can a mammal ever be alive and have “cold” blood? Endothermy ? – body temp maintained primarily by internally produced heat

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Environmental Adaptations

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  1. Mammalogy (Fall 2013 Althoff - reference FDVM Chapter 9) LEC 10B Environmental Adaptations

  2. Which is it for Mammals? • Warm-bloodied? – can a mammal ever be alive and have “cold” blood? • Endothermy? – body temp maintained primarily by internally produced heat • Homeothermy? – constant body temp maintained by physiological means • _____________ — body temp can change as a result of some amount of dormancy (hibernation, daily torpor, estivation)

  3. Benefits of Regulated Body Temperature • _____________________ – birds and mammals have 8X that of ectotherms • _____________________________________ (which is what a living organism is!) • _________________________________ enhancing neuromuscular system… thereby enhancing ability to capture prey and avoid predation

  4. Benefits of Regulated Body Temperature…con’t • Gain _______________ from temperature extremes common in nature, permitting extensive activity during a 24-hr period or on a seasonal basis • __________________ can be matched better with thermoregulatory pattern for a given environment

  5. Thermodynamic Equilibrium • Heat production: energy ____ • Heat loss: energy _____ This is delicate balancing act…it is a matter of winning or losing the ______________________!

  6. Heat Production achieved throughmetabolism of… • Food • Fat • Cellular metabolism • Muscular contraction

  7. Energy In Energy Out FOOD Energy Balance Model FDVMK Fig. 9.4, p159

  8. __________ energy “input” possible from… • Solar radiation • Thermal radiation • Convection • Conduction

  9. Summary of Energy Exchange • Fig. 9.1, p157 • Note types of energy _______ RADIATION CONDUCTION CONVECTION • Note types of energy ________ RADIATION CONDUCTION CONVECTION EVAPORATION 1 3 2 3 1 2 4

  10. Sun FDVMK Fig. 9.1, p157

  11. ADAPTATIONS TO COLD • _______________ zone = occurs within which the metabolic rate is minimal AND does not change as ambient temperature increases or decreases • _______ critical temperature = Tlc • _______ critical temperature = Tuc • Fig. 9.2, p158 – relationship of ambient temperature to O2 consumption

  12. Metabolism FDVMK Fig. 9.2, p158

  13. Adjustments to ____________ Environmental Temperatures • Change insulatory thickness a) b) • Behavior attributes a) b) c) • Changing peripheral blood flow

  14. Adjustments to Environmental Temperatures • Change insulatory thickness a) subcutaneous layer (seasonal) b) ____ piloerection • Behavior attributes a) posture b) habitat selection c) activity • Changing peripheral blood flow • ____________________

  15. AVOIDANCE of ________ • Body size and metabolism • Insulation • Appendages • Coloration • _________________________ • Reduction in level of activity • Dormancy

  16. Surface of forms used by adult male and females cottontails by season Winter Spring Autumn Summer Debris Debris + Soil Soil Althoff, D.P., G.L. Storm, and D.R. DeWalle. 1997. Daytime habitat selection by cottontail rabbits in central Pennsylvania. Journal of Wildlife Management 61(2): 450-459.

  17. Body Size & Metabolism • Larger mammals consume more oxygen than smaller animals…duh! • Larger mammals, on a MASS-SPECIFIC METABOLIC RATE basis, consume less • Fig. 9.5, p160 (handout). Can use this figure to estimate body metabolic rate for unknown species

  18. BERGMEN’S RULE • “…races from cooler climates in species of warm-blooded vertebrates tend to be ______ than races of the same species living in warmer climates” • Generalize: a) energetic advantage gained through ________________________ ________________ b) amount of _________ depends on animal’s surface area and ambient temperature

  19. Bergman’s Rule: Valid? • McNabb (1971): for 47 species of mammals studied, ______ followed this prediction • Geist (1987): “________” a) body size initially increased with latitude b) it reversed from 530 to 630N c) small body size occurs at __________ and ________ latitudes

  20. The “Poor” Weasel • Long and thin is an advantage: • Long and thin is a disadvantage:

  21. Insulation • ______________ thickness a) fat layer (seasonal) b) fur density & hair length (seasonal) c) fluff fur • _______ in fur (like beaver & muskrats) a) aquatic species do this to keep skin dry b) if air displaced by water, insulation reduced

  22. Appendages • ALLEN’S RULE: “appendages of endothermic animals are shorter in colder climates than those of animals of the same species found in warmer climates.” • Generalize: a) shorter ears, legs, muzzles, tails for more northern species b) _____________________________ • Allen’s Rule ____ “solid”

  23. Appendages Countercurrent heat exchange process in force (Fig. 9.9, p164) a) a form of peripheral heterothermy b) warm arterial blood warms colder blood returning in veins

  24. _______containing very warm blood from core of body ______containing cooled blood from body periphery _______ transferred from ________ to ________ from extremities from extremities from core

  25. Temps in ________ of CCHE Temps in ________ of CCHE Fig 9.9, p1164 FDVMK hypothetical temp changes

  26. Fig 9.9B, p164 FDVMK Regulation of External Body Temp

  27. Coloration • GOLGER’S RULE –”Races in warm and humid areas are more heavily pigmented than those in cool and dry areas” • Generalize: a) mammals closer to arctic region are paler (less pigmented) b) may reduce predation (i.e., ability to be detected)

  28. Coloration • If darker colors “absorb” more solar radiation, why are mammals in more northernly climates darker…instead of lighter? • Does this mean predation is a stronger selective force than that imposed by homeothermy (i.e., winning the energy game?)

  29. POLAR BEARS Hollow hairs to “trap” air But…. skin is _______

  30. Modification of Microclimate • Construction and use of nest • Communal nesting • Huddling--____________________ surfaces (either curling and/or contact with nest mates) • Differences can be dramatic – (see Fig. 9.14, p168 handout) • Insulation: rabbit bedsite (earlier data)

  31. ___________________ • Defined-- “period of inactivity characterized by a reduced metabolic rate and lowering of body temperature” • ___________--a form of dormancy with lower body temp, metabolic rate, respiration rate, and heart rate • ___________--”profound” dormancy: 2-50C for periods of weeks during the winter

  32. TORPOR • ______________________: can be for a day…portion of a day • Effort to achieve energy savings • Body temperature declines…but usually not below 150C • Known examples: many rodents (including Peromyscus), many marsupials, insectivores, bats, and some primates

  33. HIBERNATION • _________ period of time: can be for many weeks to several months • Effort to achieve energy savings • No mammal remains constantly in a dormant state during the entire period of hibernation • Known examples: many rodents (including many ground squirrel species like chipmunks) marmots, woodchucks, and hedgehogs

  34. What BEARS do…is not, technically hibernation They exhibit _____________________

  35. Winter Lethargy • Body temps decrease only 5 - 60C, lowering it to about 330C • Adaptation found only in _________ mammals…the only ones capable of _______ _________ required for arousal in light of only “modest” drop in body temperature

  36. Dormancy, torpor, hibernation, winter lethargy…all could be considered forms of: ADAPTIVE _______THERMIA

  37. Bats…the best of both worlds? • Some _________ • Some _________ • Some do _______! • Most _________ species (Vespertilonid bats) hibernate in caves

  38. Bats…patterns of hibernation • Typically, bat’s temp about 1 C more than ambient (typically 5 C) temperature • Arousals: a) 1 -3 weeks apart for few hours b) animal urinates, drinks water, possibly changes location

  39. Resistance to COLD: Brown vs. White Adipose Tissue • BROWN ADIPOSE TISSUE--the site of “________________________… no muscle contractions involved. It is found in ALL hibernating mammals. Multiple, small droplets with _____________________ • WHITE ADIPOSE TISSUE--single droplet of __________________________

  40. _________ Adipose Tissue (vs. White) • Highly ___________, well ____________ • Cells have _________ mitochrondria • Higher rate of O2 consumption, therefore higher _______ production • Heat produced “_______” directly to bloodstream • ______ important form of adipose tissue for insulation

  41. Adaptations to _______ • Mammalian body composition: 70% water • _________________: primarily a function of the kidneys (internal salt-water concentration) • ________________--an important device for cooling, is a major process resulting in loss of water

  42. Water Economy • Mammalian kidney (Fig. 9.19, p177) a) 1.5 nephrons per kidney b) glomerular filtration tubular reabsorption tubular secretion _______ c) papilla of the medulla (Fig. 9.20, p178)…further extension of renal capsule of into ureter pronounced for small desert rodents

  43. NEPHRON “the workhorse” of the kidney

  44. _____ “H20” limited ____ “H20” limited

  45. Kidneys…con’t • Loop of the nephron (loop of the Henle)… longer it is, more concentrated the urine • Desert heteromyids, pallid bats, canyon and house mice, and golden hamsters among those species with the most highly concentrated urine …_____________

  46. Other adaptations • Feces with low water content • Desert heteromyids, pallid bats, canyon and house mice, and golden hamsters -- most highly concentrated urine • Highly concentrated milk produced ex. Merriam’s kangaroo rat…____% water • Desert rodents, some canids, kangaroos reclaim water by consuming dilute urine & feces of young

  47. Diet • Critical for desert mammals • Many subsist on _____________-created by oxidation of food (particularly carbohydrates) …kangaroo rat gets all H20 needs from seeds consumed • Some (desert woodrats and cactus mice) consume cactus--high in H20 content • Xeric-adapted canids, badgers, etc. can subsist on H20 content obtained from ____________ of prey

  48. TEMP REGULATION • Transpirational water loss: a) through skin b) from surfaces of the respiratory tract • Sweating (a) - ______ controllable vs. • Panting (b) - _____ controllable

  49. Panting • Air flow over moist surfaces, thus controlling degree of evaporative cooling • Unlike sweating, no loss of salt…no loss of electrolytes, therefore ___________ stress • Requires ______________, thus generates more heat …a down side

  50. Cool Brains • Form of panting • Important for keeping brain temp below elevated body temp • Noted for carnivores and artiodactyls • Accomplished through _________________ heat exchange process • ________________ SINUS Fig. 9.21, p181 • Lower brain temp 2-3 C from body temp

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