And later telemetry was used

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And later telemetry was used
Started here 16 Jan. 2007
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Huey, R. B., and M. Slatkin. 1976. Cost and
benefits of lizard thermoregulation. Quart. Rev.
Biol. 51363-384.
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Empirical studies were followed by development of
biophysical models of heat and water exchange,
e.g., Porter, Bakken, Gates 1. pure theory 2.
copper models Thermoregulation was generally
viewed asonly a good thing, because our frame of
reference was Homo sapiens. What might be the
"costs" of temperature variability?
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Later, it was recognized that thermoregulation
also has costs. What might be the costs of
thermoregulation? a. exposure to predators b.
increased metabolic rate and hence energy
costs c. lost opportunity to do other
things So, focus changed to the relative costs
and benefits of thermoregulation. Sometimes
better to allow Tb to vary, and many organisms do
just that.
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For example, some lizards do not bask in the sun,
but rather are thermoconformers.
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Huey, R. B., and M. Slatkin. 1976. Cost and
benefits of lizard thermoregulation. Quart. Rev.
Biol. 51363-384.
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An Extreme Thermoconformer
Australian Gecko
Nephrurus laevissimus
Eric Pianka, U. Texas Biology 213, 9th.Lecture.ppt
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Thus, multiple solutions are possible, and one is
not necessarily "better" than another.
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3. Body size affects nearly every biological
variable. (we will return to this in a later
lecture ) 4. Behavior is an important
component of functional adjustment to the
environment. Laboratory physiologists go to
extreme lengths to standardize measurement
conditions and to control extraneous
variables. This is necessary to obtain values
that can be compared across studies, across labs,
and across species.
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But it can make the measurements of low relevance
to what goes on in nature. A trade-off exists
between getting precisely controlled
physiological measurements and making those
measurements ecologically relevant. Behavioral
adjustments are often not seen in lab settings,
either because they are just impossible, or
because the animal is "stressed out" and isn't
acting normally. Examples wild rodents often
huddle forced diving in seals leads to abnormal
physiological responses.
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Only way to overcome this is with field
observations of free-living animals and a
thorough understanding of their natural history
and behavior. Many animals simply avoid the most
stressful of conditions that occur in their
environment. Examples most desert rodents are
nocturnal many arctic or high-altitude animals
hibernate. Recent technological advances, e.g.,
miniaturized radio transmitters coupled with
thermometers, motion detectors, or force
transducers, are allowing measurements of
free-living animals.
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5. Animals ARE adapted to their
environment. Trivially, one can show that
organisms can indeed live where they do! But it
is not always obvious how they will be doing
it. Will they have adapted physiologically,
morphologically, or perhaps "only" behaviorally,
e.g., nocturnal animals avoid daytime heat
extremes? Example Lake Titicaca frog does
multiple things, but not all things.
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Lake Titicaca at high-altitude(3,800 meters or
12,500 feet) in South America
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world's highestnavigable lake
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Hutchison, V. H., H. B. Haines, and G.
Engbretson. 1976. Aquatic life at high
altitude respiratory adaptations in the
Lake Titicaca frog, Telmatobius culeus.
Respiration Physiology 27115-129. "Telmatobius
culeus has a combination of behavioral,
morphological and physiological adaptations which
allows an aquatic life in cool (10 C)
O2-saturated (at 100 mm Hg) waters at high
altitude (3,812 m). Rarely surfaces to
breathe. Greatly reduced lungs. Pronounced folds
on skin, with cutaneous capillaries penetrating
to outer layers.
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If prevented from surfacing in hypoxic waters,
use "bobbing" behavior to ventilate skin. "The
oxygen transport properties of the blood show
several distinct adaptations for an aquatic life
at high altitude. erythrocyte counts ... greater
than that reported for any frog erythrocyte
volume is the smallest ... known among
amphibians hematocrit () of 27.9 is within the
range of most amphibians oxygen capacity (ml/100
ml) of 11.7 is fairly high among amphibians
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hemoglobin content (g/100 ml) falls within the
upper range of amphibians mean cell hemoglobin
concentration (pg/um3) of 0.281 is in the upper
range of those previously observed in
amphibians lowest P50 of any frog at comparable
temperature (10 oC)"
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Summary Smallest red blood cells of any
amphibian. Most red blood cells per volume
blood. Lowest P50. Relatively high
hematocrit, hemoglobin concentration, and O2
capacity of blood. Low resting metabolic
rate. Note that the authors assumed that
everything they saw was an adaptation!!! Did not
specifically ask what does the closest relative
that does not at high altitude look like?
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A similar example African ranid frog
Trichobatrachus robustus. During the breeding
season, males have long, hair-like projections of
vascularized epidermis. They are known to sit on
clutches of eggs in streams, and presumably the
"hairs" function to increase cutaneous
respiration, thereby allowing males to remain
under water for longer periods of time (Duellman
and Trueb, 1986).
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6. The organism is a compromise. The result of
natural selection is adequacy and not
perfection. Although animals are indeed adapted
to their environments, they are far from
perfectly so. All sorts of constraints prevent
organisms from being the best that might be
theoretically possible. It has often been said
that organisms "make the best of a bad
situation," but it is not clear that they even do
that!
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Lecture 3 AllometryandScalingwith examples of
correlation and regression
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Allometry "different measure" the study of
how and why properties of organisms change in
regular ways in relation to body size. Scaling
essentially a synonymous term in biology, but
used more in engineering. Can be studied at three
levels 1. ontogenetic (intraspecific)
growth relationships during development, between
two traits or between one trait and the whole
organism a. longitudinal follow
individuals b. cross-sectional mixed-age
sample
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Allometric Growth in Human Beings Juveniles are
not Scale Models of Adults
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Zebrafish again, large changes in shape are
occurring ...
Randall, D., W. Burggren, and K. French. 2002.
Eckert animal physiology mechanisms and
adaptations. 5th ed. W. H. Freeman and Co., New
York.
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Allometric growth is differential rates of growth
of two or more traits. It is often well described
by the equation Y bXa where Y is one trait
(e.g., metabolic rate), b is a constant, a is the
"allometric" or "scaling" coefficient, and X is
the other trait (often a measure of body size,
e.g., mass or length).
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Y bXa This equation describes a logarithmic
relationship. It can be made linear by taking the
logs of the values measured for each trait, or by
plotting on log-log graph paper. If we take logs,
then the equation becomes log Y log b a log
X This equation describes a straight linewith a
being the slope.
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"Reptiles" (not a good term, phylogenetically
speaking) are a good model for studies of
ontogenetic allometry because 1. they have
little or no parental care, so newly hatched
or born offspring must fend for themselves,
forage, escape from predators, etc. 2. huge
size range from juvenile to adult 3.
no metamorphosis to complicate the
picture.
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An Example of Studying Ontogenetic Allometry
Amphibolurus (Ctenophorus) nuchalisfrom central
Australia
Australian National Bird
Recent Hatchling
Adule Male
Adule Female
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Fowlers Gap a Research Station and Working
Sheep Ranch run by the University of New South
Wales
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Fowlers Gap a Research Station and Working
Sheep Ranch run by the University of New South
Wales
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Area around Fowlers Gap Lizards often Bask on
Fence Posts, or use them for Territorial Outposts
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Fences can be Hazardous to Emu and Kangaroo!
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The Wet Season can be Hazardous to Vehicles!
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Lizard Burrows can be in Surprising Places
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Amphibolurus (Ctenophorus) nuchalis
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Exponent (slope of line) is lt 1, so liver
exhibits negative ontogenetic allometry
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log base 10 version
95 Confidence Interval on slope is 0.747 - 1.063
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Logarithmic axes.
Note that the log transform also 1. shrinks
large values, expands small 2. homogenizes
variances
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Exponent (slope of line) is gt 1, so thigh muscle
exhibits positive ontogenetic allometry
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95 Confidence Interval on slope is 1.104 - 1.212
Juveniles are not just scale-models of adults!
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Relationship is non-linear even on log-log scale.
Again, juveniles are not just miniature adults!
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Non-linear ontogenetic allometries (on log-log
scale) of physiological traits also occur in
garter snakes and water snakes, and in many
amphibians around metamorphosis.
The common garter snake, Thamnophis sirtalis
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An Altricial Mammal, the house mouse
Randall, D., W. Burggren, and K. French. 2002.
Eckert animal physiology mechanisms and
adaptations. 5th ed. W. H. Freeman and Co., New
York.
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Some Differences between Hatchling and Adult
Amphibolurus (Ctenophorus) nuchalis
Ratio 1 g 50 g 50/1 Liver, body
mass 3.4 2.3 0.69 Heart, body mass 0.27
0.40 1.51 Thigh, body mass 1.31
2.44 1.86 Hindlimb span/SVL 1.52
1.25 0.82 Hematocrit () 6.0 20.7 3.44 How
might these differences affect organismal
performance?
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Additional levels at which allometry can be
studied 2. static size relationships of traits
among individuals of the same age (typically
adults) 3. evolutionary (interspecific) size
relationships among species This is a perennial
favorite of comparative and ecological
physiologists! It pervades the fields. Many
books have been written.
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Books on Allometry (mainly interspecific) Brown,
J. H., and G. B. West, eds. 2000. Scaling in
biology. Oxford Univ. Press, New York. Calder, W.
A. 1984. Size, function and life history.
Harvard Univ. Press, Cambridge. Peters, R. H.
1983. The ecological implications of body
size. Cambridge Univ. Press, Cambridge. Reiss, M.
J. 1989. The allometry of growth and
reproduction. Cambridge Univ. Press,
Cambridge. Schmidt-Nielsen, K. 1984. Scaling why
is animal size so important? Cambridge Univ.
Press, Cambridge.
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Allometry Predictions from First
Principles A Tool to Understand
Organismal Design and Adaptation
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Scaling Relationships Based on First
Principles For geometrically similar objects
(scale models) Relationships with
Length Circumference ? Length1 (for a circle,
circumference ? 2 p radius1) Cross-sectional
Area ? Length2 (for a circle, area ? p
radius2) Surface Area ? Length2 Volume ?
Length3 (for a sphere, volume ? 4/3 p
radius3) Mass ? Length3 (assuming that density
remains constant)
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Consider a cube ...
Length 1 2 3 Area 1 4
9 Circum- 4 8 12 ference Volume 1 8
27
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Relationships with Mass Volume is proportional to
Mass1.00 Length is proportional to
Mass0.33 Surface Area is proportional to
Mass0.67 Predictions for geometrically similar
animals Blood Volume is proportional to
Mass1.00 Mass of Organ is proportional to Body
Mass1.00 Limb Length is proportional to Body
Mass0.33 Skin, Gill or Lung Surface Area ?
Mass0.67
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Allometric Expectations Based on First Principles
for Geometrically Similar Objects (scale models)
serve as Null Models for Comparison with Real
Organisms. Deviations from "isometry" may
indicate how evolution has modified organisms
from geometric similarity in order to maintain
(more or less) functional abilities across a
range of body sizes. (Only may indicate because
this presumes that evolutionary changes in size
because of random genetic drift, in the absence
of seleciton, would occur along lines of
geometric similarity )
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Got through this slide 16 Jan. 2007
Example Mammalian Skeletal Mass As body mass
becomes larger, would need bone strength to keep
up. Strength ? cross-sectional area, so would
need bone cross-sectional area ? M1.00 to support
the load. Mass of skeleton would be M1.00 X M0.33
M1.33 Empirical result skeletal mass ?
M1.080.04 So, large mammals should not be able
to do what small ones do (unless all are
"over-designed"). In fact, large mammals have
more upright postures, less dynamic less risky
locomotor behavior (elephants dont jump).