Are such changes reversible, or do they carry over as the animals continue to age

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Are such changes reversible, or do they carry
over as the animals continue to age?
Started here 11 Jan. 2007
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Reversal Experiment
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Control Groups
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"Water-Restricted, then Free Water" group drank
copiously when reversed to free water and
remained significantly higher than Free Water
group
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Food intake is intimately linked with water
consumption in house mice
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The effects of early-life water restriction are
not completely reversible
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Modern evolutionary physiology arose in the late
1970s and early 1980s. Three main contributing
factors
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2. attempts to integrate quantitative
genetic perspectives into evolutionary
biology and behavioral ecology a. focus on
individual variation as raw material for
natural selection, not just "noise" b.
attempts to estimate heritability of traits
Bumpus, H. C. 1899. The elimination of the unfit
as illustrated by the introduced sparrow, Passer
domesticus. Mar. Biol. Lab., Biol. Lect. (Woods
Hole, 1898), pp. 209-226.
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3. attempts to integrate phylogenetic
perspectives into comparative biology
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Evolution from a Physiological Perspective and
vice versa recurring themes in ecologicaland
evolutionary physiology 1. How do Different
Kinds of Organisms Work? a. Discover general
principles of organismal function, such as
homeostasis or the scaling of metabolic rate
with body mass. b. Find exceptions to the rules,
species that are "outliers" from the general
trend. c. Determine whether there exist
multiple solutions to a given adaptive
problem.
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Because all organisms on this planet are
descended from common ancestors - and probably
from a single common ancestor - general
biological principles are likely to occur in a
strongly hierarchical (phylogenetic)
pattern. Related organisms tend to resemble each
other in terms of how they are built and how they
do things for example, use of DNA as a
genetic material, structure of eukaryotic
cell membranes, responses to changes in ambient
temperature by mammals.
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2. Extremes of Adaptation, "Model" Species, and
The August Krogh Principle a. Identification of
similarities among species allows the
possibility that certain species may be able
to serve as "model systems" for studying
basic physiological processes. b. August Krogh
noted that for any physiological
principle there exists an organism
especially well suited for its study
(e.g, giant axons of squid).
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c. Similarly, organisms living in extreme
environ- ments are especially likely to
exhibit clear examples of evolutionary
adaptation, because of the presumably
intense past selection. They can also serve to
illustrate the range of evolutionary
possibilities. But we must remember that the
organisms alive today -- and hence available
for physiological study -- are but a small
fraction of what has existed. We have
no guarantee that we can observe the range
of possibilities even among the most extreme
of living species.
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Example Dinosaurs, such as Spinosaurus
http//www.biology.ucr.edu/people/faculty/Garland/
Spinosaurus_30_Theo_29_Sep_2004.jpg
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Example the largest terrestrial mammal that
ever lived (Baluchitherium) was much larger than
living elephants, mammoths or mastodons. An
extinct hornless rhinoceros that lived in the
Oligocene epoch (30- 20 million years ago).
Fossilized remains found in central Asia show
that it was over 5 m high, with a heavy
giraffe-like body.
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Giant birds (both flying and flightless) once
existed, giant dragonflies. And then there were
plesiosaurs, ichthyosaurs, etc. Many
transitional forms are now extinct. Environmental
conditions differed as well, e.g., temperature
and atmospheric oxygen.
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Opthalmosaur Pterosaur
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(No Transcript)
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Plate 8.2 The last living Tasmanian tiger,
Hobart Zoo, 1933.
Plate 9.1 Rear view of the last living Tasmanian
tiger, Hobart Zoo, 1933.
Died night of 7 September 1936
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3. Are Species Differences in Physiology
Adaptive? The neo-Darwinian synthesis, with its
emphasis on natural selection as the major
driving force in evolution, led to the view that
virtually all features of organisms are
adaptive. Comparative physiologists have
routinely viewed any differences among species as
adaptations to their different life styles. And,
of course, many examples clearly do represent
strong evidence for adaptation.
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Nonetheless, not all features of organisms
represent adaptations to current environmental
conditions. Some represent simple inheritance
from ancestors. "Four legs may be optimal,
but tetrapods have them by conservative
inheritance, not selected design." (S. J.
Gould, 1980, p. 44) A similar statement could be
made about insects (6 legs) or spiders (8
legs). Genetic variation for leg number is
virtually absent in extant populations, so
natural selection cannot change it. A sort of
"phylogenetic constraint."
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"Darwin pointed out in The Origin of Species that
the sutures in the skull of young mammals'have
been advanced as a beautiful adaptation for
aiding parturition, and no doubt they facilitate,
or may be indispensable for this act
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"Darwin pointed out in The Origin of Species that
the sutures in the skull of young mammals'have
been advanced as a beautiful adaptation for
aiding parturition, and no doubt they facilitate,
or may be indispensable for this act but as
sutures occur in the skulls of young birds and
reptiles, which have only to escape from a broken
egg, we may infer that this structure has arisen
from the laws of growth, and has been taken
advantage of in the parturition of the higher
animals.'
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Gould and Vrba (1982) have offered the term
exaptation to describe features that now enhance
fitness, but were not built by natural selection
for their current role." (Futuyma, 1986, p. 257)
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4. Are Organisms Optimally Designed? In addition
to presuming that most features of organisms are
adaptations, a common perspective in comparative
physiology is to view organisms as optimally
designed, i.e., more-or-less perfectly adapted in
some sense. "We do not think a functional
explanation complete until we can show that
a structure or movement is optimal (by some
plausible criterion) for the proposed
function." (Alexander, 1988, p. 237)
"Evolution by natural selection is a process
of optimization." (Alexander, 1996, p. 2)
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This is a controversial view (more later in
course), and many workers have a very different
expectation about "how good" organisms are,
e.g., "Natural selection increases fitness
but it produces systems that function no
better than they must. It yields adequacy
of adaptation rather than perfection."
(Bartholomew, 1987, p. 14)
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5. What is the Origin of Allometric
Relationships? Allometry how and why
properties of organisms change in regular ways in
relation to body size. Scaling essentially a
synonymous term in biology, but used in other
ways in engineering, image processing, computer
science. Example does "smartness" vary with
body size or among evolutionary lineages?
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Large animals have relatively small brains.
log-log axes
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Vertical deviations from "line of best fit"
(residuals) indicate deviation from general
effect of body size.
log-log axes
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http//www.google.com/search?hlenlroidefmore
deflenqdefineallometry 17 Jan.
2006 Definitions of allometry on the
Web Generally, the effect of size on shape.
Specifically, any relationship of anatomical
variables that fits the equation Y AX k (A is a
constant, the exponent k the coefficient of
allometry).www.modernhumanorigins.com/a.html
Change in a measurable aspect of an organism
(such as shape) with increase or decrease in
size.www.csupomona.edu/jcclark/classes/bio406/gl
ossary.html A disproportionate relationship
between size of a body part and size of the whole
body.www.intuitive.com/coolsites/examples/ch5-1.h
tml The relationships between various aspects of
a tree's size and shape. See the allometry topic
for more.www.sortie-nd.org/help/manuals/help/more
_info/glossary.html The study of the change in
proportion of various body parts as a consequence
of their growth at different rates.highered.mcgra
w-hill.com/sites/0767430220/student_view0/glossary
.html The study of the relative growth of a part
of an organism in relation to the growth of the
whole wordnet.princeton.edu/perl/webwn
Allometry is the science studying the
differential growth rates of the parts of a
living organism's body part or process.
en.wikipedia.org/wiki/Allometry
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http//www.google.com/search?hlenlroidefmore
deflenqdefinescaling 17 Jan. 2006 Definitions
of scaling on the Web The act of arranging in a
graduated series act of measuring or arranging or
adjusting according to a scale ascent by or as
if by a ladderwordnet.princeton.edu/perl/webwn
In Euclidean geometry, scaling is an affine,
linear transformation that can enlarge or
diminish an object by certain factors. See also
homothety. en.wikipedia.org/wiki/Scaling_(geometr
y) In computer networking, scaling is the
ability for a network to continue to function
with limited or no degredation in performance as
the number of users on the network increases.
en.wikipedia.org/wiki/Scaling_(computer_network)
The measuring of lengths and diameters of logs
and calculating deductions for defect to
determine volume.www.woodlot.bc.ca/swp/myw/html/2
1_Glossary.htm A means of calculating the amount
of enlargement or reduction necessary to
accommodate a photograph within the area of a
design.www.purdue.edu/printingservices/support/gl
ossary/glossrtoz.htm The enlargement or
reduction of an image or copy to fit a specific
area.www.millerbrosengraving.com/resources/glossa
ry.html Determining the proper size of an image
to be produced (or reduced/enlarged). It is
important that both directions be scaled in order
to ensure proper fit in the final
reproduction.www.relyprint.com/help_dictionary.ht
ml Reduction or enlargement of artwork, which
can be proportional (most frequently used) or
disproportional. In desktop publishing, optimal
scaling of bitmaps is reduction or enlargement
that will avoid or reduce moiré
patterns.www.printingyoucantrust.com/glossary.cfm
Determining the proper size of an image to be
reduced or enlarged to fit an area.www.careydigit
al.com/support/glossaryr-s.html
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Lecture 2 Evolution and thePhenotypic
Hierarchy Accomplishments of Physiological
Ecology
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A General Question How do traits atdif ferent
levels of biological organization evolve in a
coherent fashion?
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Dar winian Fi t nessage at 1st reprod.,
fecundity, lifespan
Organisms are complex and hierarchical entities.
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Although scientists tend to specialize on
particular levels of biological organization,
organisms evolve as coordinated
wholes. Therefore, cross-disciplinary studies are
required to understand how organisms work and
evolve. The inseparability of physiology from
behavior and from the environmental context has
long been a central tenant of physiological
ecology. Only in the last 20 years or so have
attempts been made to formalize such
relationships conceptually and in operational
terms, but the general problem has long been
appreciated ....
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"The whole organism is so tied together that when
slight variations in one par t occur, and are
accumulated through natural selection, other
parts become modified. (Darwin, 1859, The
Origin of Species)
This is aver y
impor tant subject, mostimper fectly understood."
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Dar winian Fi t nessage at 1st reprod.,
fecundity, lifespan
Behavior
Selection a correlation between fitness and one
or more traits at lower levels of organization.
OrganismalPer formance
OrganSystems
Organs
Tissues
Cells
Organelles
Proteins, etc.
DNA
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Dar winian Fi t nessage at 1st reprod.,
fecundity, lifespan
Behavior
OrganismalPer formance
OrganSystems
In nature, selection may of ten act most directly
on behavior.
Organs
Tissues
Cells
Organelles
Proteins, etc.
DNA
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"Many if not most acquisitions of new structures
in the course of evolution can be ascribed to
selection forces exerted by newly acquired
behaviors ... (Mayr, 1982, p. 612)
Behavior, thus, plays an important role as the
pacemaker of evolutionary change.
Most
adaptive radiations were apparently caused by
behavioral shifts."
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Dar winian Fi t nessage at 1st reprod.,
fecundity, lifespan
Behavior
Wherever it acts, selectionmay cause changes in
other traits at that level, and at other levels,
but perhaps with some lag.
OrganismalPer formance
OrganSystems
Organs
Tissues
Cells
Organelles
Proteins, etc.
DNA
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Behavior
A Simple Model of Correlated Responses to
Selection on Behavior The "Behavior Evolves
First" Hypothesis
OrganismalPer formance
OrganSystems
Organs
Tissues
Assuming that Traits at all Levels Have Some
Genetic Basis
Cells
Organelles
Proteins, etc.
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Behavior
OrganismalPer formance
OrganSystems
Organs
Tissues
Cells
Organelles
Proteins, etc.
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Behavior
OrganismalPer formance
OrganSystems
Organs
Tissues
Cells
Organelles
Proteins, etc.
45
Behavior
OrganismalPer formance
OrganSystems
Organs
Tissues
Cells
Organelles
Proteins, etc.
46
Behavior
OrganismalPer formance
OrganSystems
Organs
Tissues
Cells
Organelles
Proteins, etc.
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Behavior
OrganismalPer formance
OrganSystems
Organs
Tissues
Cells
Organelles
Proteins, etc.
48
Behavior
OrganismalPer formance
OrganSystems
Organs
Tissues
Cells
Organelles
Proteins, etc.
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Behavior
OrganismalPer formance
OrganSystems
Organs
Tissues
Cells
Organelles
Proteins, etc.
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Cinclus mexicanus
The Dipper dives to forage. Presumably, selection
favored diving to exploit an underutilized food
resource.
Figure 3 (page 257) from D. J. Futuyma. 1986.
Evolutionary biology. 2nd. Ed. Sinauer
Associates, Sunderland, Massachusetts.
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Cinclus mexicanus
But dippers show r elatively few morpho-logical
or physiological specializations that might
enhance the ability to dive.
Figure 3 (page 257) from D. J. Futuyma. 1986.
Evolutionary biology. 2nd. Ed. Sinauer
Associates, Sunderland, Massachusetts.
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Natural Sexual Selection
Act On
Behavior
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Natural Sexual Selection
Act On
Behavior
Constrain
Organismal Performance Abilities
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Natural Sexual Selection
Act On
Behavior
Constrain
Morphology, Physiology, Biochemistry
Organismal Performance Abilities
Deter- mine
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Natural Sexual Selection
Act On
Behavior
This model presumes that animals can be maximally
motivated to perform ...
Constrain
Morphology, Physiology, Biochemistry
Organismal Performance Abilities
Deter- mine
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Natural Sexual Selection
Act On
Behavior
Hormones
Constrain
Morphology, Physiology, Biochemistry
Organismal Performance Abilities
Deter- mine
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Traditionally, many studies in morphology and
physiology would just study traits at the lowest
level (morphology, physiology, biochemistry), and
then try to correlate variation here with
variation in behavior or ecology. Examples 1.
correlating leg length with habitat usage of
lizards, without ever showing empirically that
leg length affects some measure of per formance,
such as sprinting or climbing abilities. 2.
correlating bill dimensions of birds with diet,
without showing that bill proportions actually
affect feeding abilities on different types of
food.
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3. correlating wing dimensions of bats with life
style, generally in the absence of studies
measuring effects of wing dimensions on flying
abilities. 4. relating the thermal dependence of
an enzyme activity or of the contractile
properties of isolated muscles to the temperature
at which animals normally live.
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Time required for exposure to 37oC to inactivate
myofibrillar ATPase is positively correlated with
thermal environment across species of fish
(Johnston and Walesby, 1977).
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Maximum isometric twitch tension of lizard
muscles is positively correlated with PBT across
species(Licht, Dawson, and Shoemaker, 1969).
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A major conceptual advance in the last 25 years
has been adopting the perspective that you really
need to make some measures of organismalper
formance to allow a clear link between
lower-level traits and behavior/ecology.
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The Accomplishments of Physiological Ecology
Bennett, A. F. 1987. Pages 1-10 in M. E. Feder,
A. F. Bennett, W. W. Burggren, and R. B. Huey,
eds. New directions in ecological physiology.
Cambridge Univ. Press., Cambridge, U.K. New
York. 1. Energy availability and utilization are
important constraints on animal function. Energy
availability can impose constraints on what
organisms can do. For poikilotherms, these
constraints can be temperature dependent.
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Measurement of energy exchange leads easily to
links with behavior and ecology 1. optimal
foraging theory - costs and benefits usually
phrased in energy 2. population- and
community-level usage of energy affect
ecosystem dynamics Evolutionary linkage is often
via life history theory, which deals with things
like optimal size and number of offspring, given
a limited amount of energy available for
reproduction trade-offs can be important if
energy is truly limiting.
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2. Body temperature regulation is expensive in
time and energy. Its alternative, temperature
conformity, entails variability in all
physiological processes. Thermoregulation has
long been a favorite subject of study. Cowles, R.
B., and C. M. Bogert. 1944. A preliminary study
of the thermal requirements of desert
reptiles. Bull. Amer. Mus. Nat. Hist.
83265-296. Bogert, C. M. 1949. Thermoregulation
in reptiles, a factor in evolution. Evolution
3195-211.
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Early papers showed that desert lizards often
maintained high (35-40oC) and relatively stable
body temperatures when active.
Dipsosaurus dorsalis,the desert iguana
Cnemidophorus tigris,the whiptail
Uma scoparia,the fringe-toed lizard
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This was different from what most people thought,
who had typically observed lizards in captive
situations where they could not thermoregulate
normally (e.g., no heat lamp). Studies were made
possible by a technological advance
quick-registering mercury thermometers. Grab 'em
and jab 'em! Noose 'em and goose 'em! (Find
'em and grind 'em!)
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http//www.wildherps.com/species/S.occidentalis.ht
ml
Got through this slide 11 Jan. 2007
Data from Prof. Stephen C. Adolph, Department of
Biology, Harvey Mudd College, Claremont,
California