Environmental Adaptations
Mammalogy (Spring 2015 Althoff - reference FDVM Chapter 9)
LEC 10B
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)
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
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
Thermodynamic Equilibrium
• Heat production: energy ____
• Heat loss: energy _____
This is delicate balancing act…it is a matter of winning or losing the ______________________!
Heat Production achieved through
metabolism of…
• Food
• Fat
• Cellular metabolism
• Muscular contraction
FOOD
FDVMK Fig. 9.4, p159 Energy Balance Model
Energy In Energy Out
__________ energy “input” possible from…
• Solar radiation
• Thermal radiation
• Convection
• Conduction
Summary of Energy Exchange
• Fig. 9.1, p157• Note types of energy _______
RADIATION CONDUCTIONCONVECTION
• • Note types of energy ________
RADIATION CONDUCTIONCONVECTION EVAPORATION
1
1
23
2 43
Sun
FDVMK Fig. 9.1, p157
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
Met
abo
lism
FDVMK Fig. 9.2, p158
Adjustments to ____________
Environmental Temperatures • Change insulatory thickness
a) b)
• Behavior attributesa) b) c)
• Changing peripheral blood flow
Adjustments to
Environmental Temperatures
• Change insulatory thicknessa) subcutaneous layer (seasonal)b) ____ piloerection
• Behavior attributesa) postureb) habitat selectionc) activity
• Changing peripheral blood flow• ____________________
AVOIDANCE of ________
• Body size and metabolism• Insulation• Appendages• Coloration• _________________________• Reduction in level of activity• Dormancy
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.
Surface of forms used by adult male and females cottontails by season
Debris
Debris + Soil
Soil
Winter Spring Summer Autumn
Body Size & Metabolism • Larger mammals consume more oxygen than
smaller animals…duh!
• Larger mammals, on a MASS-SPECIFICMETABOLIC RATE basis, consume less
• Fig. 9.5, p160 (handout). Can use this figure to estimate body metabolic rate for unknown species
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
Bergman’s Rule: Valid?
• McNabb (1971): for 47 species of mammals studied, ______ followed this prediction
• Geist (1987): “________”a) body size initially increased with
latitudeb) it reversed from 530 to 630Nc) small body size occurs at __________
and ________ latitudes
The “Poor” Weasel
• Long and thin is an advantage:
• Long and thin is a disadvantage:
Insulation
• ______________ thicknessa) 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, insulationreduced
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 speciesb) _____________________________
• Allen’s Rule ____ “solid”
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
_______ transferredfrom ________ to ________
______ containing cooled blood from body periphery
_______ containing very warm blood from
core of body
from core
from extremities
from extremities
Fig 9.9, p1164 FDVMK hypothetical temp changes
Tem
ps
in _
____
___
of
CC
HE
Tem
ps
in _
____
___
of
CC
HE
Fig 9.9B, p164 FDVMK Regulation of External Body Temp
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)
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?)
POLAR BEARSHollow hairs to
“trap” air
But….skin is _______
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)
___________________
• 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
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
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
What BEARS do…is not, technically
hibernation
They exhibit
_____________________
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
Dormancy, torpor, hibernation, winter lethargy…all could be considered forms
of:
ADAPTIVE _______THERMIA
Bats…the best of both worlds?
• Some _________• Some _________• Some do _______!• Most _________ species (Vespertilonid bats)
hibernate in caves
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 hoursb) animal urinates, drinks water,
possibly changes location
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 __________________________
_________ 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
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
Water Economy
• Mammalian kidney (Fig. 9.19, p177)a) 1.5 nephrons per kidney b) glomerular filtration
tubular reabsorptiontubular secretion
_______ c) papilla of the medulla (Fig. 9.20, p178)…further extension of renal capsule of into ureter pronounced for small desert
rodents
NEPHRON
“the workhorse”of the kidney
_____ “H20” limited ____ “H20” limited
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 …_____________
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 producedex. Merriam’s kangaroo rat…____% water
• Desert rodents, some canids, kangaroos reclaim water by consuming dilute urine & feces of young
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
TEMP REGULATION
• Transpirational water loss:a) through skinb) from surfaces of the respiratory tract
• Sweating (a) - ______ controllablevs.
• Panting (b) - _____ controllable
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
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
ARTERIAL BLOOD
_____ VENOUS BLOOD
______ VENOUS BLOODTO BRAIN
Saliva Spreading
• Known for some rodents & marsupials
• Saliva spread on limbs, tail, chest, etc.
• ______________ heat loss
• _____ as efficient as sweating because fur must be ______ wet before heat is lost from underlying skin
What is Estivation?
• Is it a form of dormancy?
• Is it a phenomenon associated with a) cold conditions …or…b) hot and dry conditions?
• Name a species known to exhibit estivation
Explain this…dealing with _____ temperatures
• Fig. 9.29, p186• Activity patterns of antelope ground squirrels, Fig.
9.30, p187• Dromedary, Fig. 9.32, p187• The camel’s hump p188• Desert antelope: oryx, gazelles, and elands, p188
including Fig. 9.33 on p189