Transcript MAMMALOGY AS A SCIENCE

Mammalogy
(Spring 2015 Althoff - reference FDVM Chapter 9)
Environmental Adaptations
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
Energy In
Energy Out
FOOD
FDVMK Fig. 9.4, p159
Energy Balance Model
__________ energy “input” possible from…
• Solar radiation
• Thermal radiation
• Convection
• Conduction
Summary of Energy Exchange
• Fig. 9.1, p157
• Note types of energy _______
1 RADIATION
3 CONDUCTION
2 CONVECTION
•
• Note types of energy ________
3 CONDUCTION
1 RADIATION
2 CONVECTION 4 EVAPORATION
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
Metabolism
FDVMK Fig. 9.2, p158
Adjustments to ____________
Environmental Temperatures
• Change insulatory thickness
a)
b)
• Behavior attributes
a)
b)
c)
• Changing peripheral blood flow
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
• ____________________
AVOIDANCE of ________
•
•
•
•
•
•
•
Body size and metabolism
Insulation
Appendages
Coloration
_________________________
Reduction in level of activity
Dormancy
Surface of forms used by adult male and females cottontails by season
Winter
Spring
Summer
Autumn
100
Debris
90
% of observations
80
70
60
Debris
+ Soil
50
40
30
Soil
20
10
0
Females
Males
Females
Males
Females
Males
Females
Males
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.
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
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
latitude
b) it reversed from 530 to 630N
c) small body size occurs at __________
and ________ latitudes
The “Poor” Weasel
• Long and thin is an advantage:
• Long and thin is a disadvantage:
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
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”
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
_______ containing
very warm blood from
core of body
______ containing cooled
blood from body periphery
_______ transferred
from ________ to ________
from
extremities
from
extremities
from core
Fig 9.9, p1164 FDVMK
hypothetical temp changes
Temps in ________ of CCHE
Temps in ________ of CCHE
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 BEARS
Hollow 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 hours
b) 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 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
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 produced
ex. 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 skin
b) from surfaces of the respiratory tract
• Sweating (a) - ______ controllable
vs.
• 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
______ VENOUS BLOOD
TO BRAIN
ARTERIAL BLOOD
_____ VENOUS BLOOD
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