Download What is “Comparative Animal Physiology”? Central Themes of

PSLY 4210/5210
!Comparative Animal Physiology
!What is Comparative Animal Physiology ?!
What is Comparative Animal
Physiology ?!
!Spring 2010
Central Themes of Comparative
Animal Physiology!
!Comparing physiologies of
Much the same as for biology in general:!
animals: What does it mean? !
  Comparing physiological
mechanisms?!
  Comparing physiologically
adaptive strategies?!
  Comparative molecular biology? !
Relationship between animal form and
function!
  Relationship between maintenance of
complexity and homeostasis!
  Acquiring and using energy!
  Environmental constraints!
  Evolution and adaptation!
  Biodiversity and uniformity!
 
Insights into the Relationships Between "
Organisms and Their Environment:!
Animals are adapted to their environments through
past evolution.!
  The organism is a compromise. The result of natural
selection is adequacy (“Just good enough”), not
perfection.!
  Energy availability and utilization are important
constraints on animal function.!
  Body temperature regulation is expensive in time and
energy. Its alternative (temperature conformity),
results in variability in all physiological processes.!
  Body size affects nearly every biological variable.!
  Behavior is an important component of functional
adjustment to the environment. Environmental cues
help determine behaviors.!
 
Emergent Properties of Life!
Hierarchical Organization of Life!
Biomolecules and macromolecules!
  Cells and subcellular components (e.g., organelles, membranes,
and cytoplasmic elements)!
  Cells/Organisms – individual living things !
  Populations –freely-interbreeding"
organisms inhabiting the same place at the"
same time!
These two individuals share
  Species – all organisms that can"
more than 98% of their
actually or potentially interbreed"
genomes (perhaps less than
and produce fertile offspring!
500 of their genes differ)!
  Communities – collections of populations"
of different species inhabiting the same place at the same time!
  Ecosystems – living organisms (communities) and their non-living
environments!
  Biosphere – all of Earth s ecosystems: every part of Earth where life
exists!
Most commonly studied by physiologists!
 
Figure 1.1 The study of physiology integrates knowledge at all levels of organization
!Organisms are living systems. Systems are"
organized collections of parts. When energy is"
applied to systems, then new emergent properties"
appear that are more complex than the system’s"
collective properties ( the whole is greater than the"
sum of its parts ) !
Cells: perform synthesis of large molecules and"
chromosomal replication!
  Populations: exhibit age structure, genetic diversity,"
natural selection!
  Species: have reproductive isolating mechanisms (behaviors,
chromosomal or germ cell incompatibilities)!
  Communities: have coevolutionary relationships between species (e.g.,
competition, predation), and undergo predictable changes with time
(succession)!
  Ecosystems: recycle nutrients between living organisms and the nonliving environment!
  Biosphere: living things affect, and are affected by, the Earth’s
biogeochemistry and climatic conditions!
 
Topic 1 – 1!
PSLY 4210/5210
!Comparative Animal Physiology
!What is Comparative Animal Physiology ?!
Environmental Challenges to Organisms
Survival and Reproduction (Fitness)!
!Spring 2010
Figure 1.6 Mixed conformity and regulation in a single species
Temperature extremes!
Osmotic pressure extremes!
  Lack of free water!
  Low partial pressures of oxygen!
  Trace element deficiencies!
  Atmospheric/hydrostatic pressure extremes!
  Radiation!
  pH!
Organisms must adapt to these challenges.!
 
 
Body Size is Important in Many
Physiological Processes!
Figure 1.8 Length of gestation scales as a regular function of body size in mammals
Larger animals:!
  Have fewer predators!
  Compete more successfully for mates!
  Produce more offspring!
  Retain heat better!
  Resist starvation better!
 
 
Use energy at a lower rate per unit mass!
Can store more energy!
!Many anatomical structures and
physiological functions scale with size.!
Example: Flapping Flight"
in Birds and Insects!
Types of Comparisons Between Species!
1)!Convergence/divergence!
 
 
Animals belonging to distantly related taxa
often evolve adaptations that allow them to
have similar modes of life!
Analogous structures and physiological
functions:!
 
 
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Form and prior evolutionary history constrains
function!
Different embryonic derivation and structural
organization)!
Physiological machinery and morphological
structures are totally different!
 
 
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High degree of"
convergence, e.g.,"
hummingbirds"
and sphinx moths!
Overlapping body sizes, similar body/wing
shapes and aerodynamics (both beat their
wings in the same figure-eight "
pattern!
Both hover in front of flowers"
to drink nectar!
Topic 1 – 2!
PSLY 4210/5210
!Comparative Animal Physiology
!What is Comparative Animal Physiology ?!
Figure 1.4 Structures that are similar in gross appearance, functional performance, and adaptive
significance can differ dramatically in details of how they are assembled and work
Example: Flapping Flight"
in Birds and Insects!
 
 
Hovering is"
the most"
energetically"
expensive"
form of flight!
Hummingbirds"
and sphinx"
moths have"
similar energy"
consumption"
rates!
!Spring 2010
Bartholomew and Casey (1978);
Bartholomew and Lighton (1986)
Figure 1.4 Structures that are similar in gross appearance, functional performance, and adaptive
significance can differ dramatically in details of how they are assembled and work
No
blind
spot
Blind
spot
Types of Comparisons Between Species!
2) !Adjustments that permit closely related species to live in dissimilar environments!
!Example: sea lions and fur sea lions in equatorial,
temperate and Arctic climates!
Pinnipeds are extremely well-adapted to cold: insulated
from cold water by combinations of size, subcutaneous
fat, and fur, but!
  Easily overheated on land!
 
Can die if forced to walk a few hundred meters, even when
overcast and <10 °C!
  Unable to lose the heat they generate by terrestrial
locomotion, body temperature rises to 43 °C or more!
 
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Fur Sea Lions in Equatorial Climates!
California Sea Lions in Equatorial Climates!
!Although otherwise circumpolar in distribution, one
species of fur seal lions (Arctocephalus
galapagoensis) breeds in the Galapagos Islands:!
!One subspecies of California sea lions
Water is 12 to 18 °C below"
body temperature!
Easily lose heat in water from"
naked, well-vascularized"
flippers!
Avoid heat of day by hiding in"
caves, or on talus slopes among"
boulders!
During trade wind season, stay on low rocky ledges on
windward side, where the spray can reach them!
(Zalophus californianus wollebacki) also lives
in the Galapagos Islands:!
Switch breeding behavior from maintaining
terrestrial breeding territories to defending aquatic
ones: remain partly or fully"
submerged in tide pools or"
channels !
  Avoid heat by restricting"
terrestrial activity to"
crepuscular hours or"
nighttime!
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Topic 1 – 3!
PSLY 4210/5210
!Comparative Animal Physiology
!What is Comparative Animal Physiology ?!
Types of Comparisons Between Species!
Types of Comparisons Between Species!
3) Do related species living in the same difficult environment have
similar responses to that environment? Example: desert lizards
of the family Iguanidae:"
"
"
"
"
!
"
"
"
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!chuckwalla
!desert iguana
!!
Both can feed on dried vegetation and extract water from it.!
High temperature tolerances allow longer daily activity: longer
time interval to acquire and digest this low-quality diet.!
Similar adaptations for fermentative digestion.!
Nasal salt glands to deal with excess Na+/ K+ in diet!
4)!How do distantly-related taxa adapt to the
same or similar difficult environment?!
Example: flying insects that breed during the winter!
  Normally, insects at < 0 °C are immobilized.!
  However, a few unrelated species (a scarab beetle
and several geometrid moths) carry out breeding
flights at < 0 °C (presumably to avoid predation).!
  Beetles have low wing loading: rapid wing beats
raise body temperature to performance levels.!
  Moths have high wing loading: can fly with slow
wing beats and low energy expenditure.!
Specific Questions Arising from
Comparisons Between Species!
Specific Questions Arising from
Comparisons Between Species!
Do species comparisons produce merely
a series of adaptive stories ?!
  Do species comparisons simply
demonstrate that animals can live where
they do?!
  Does the approach based on species
comparisons have adequate analytical
paradigms?!
 
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Do species comparisons produce merely
a series of adaptive stories ?!
 
Yes, but these need not be the only
( trivial ) results!
Do species comparisons simply
demonstrate that animals can live where
they do?!
  Does the approach based on species
comparisons have adequate analytical
paradigms?!
 
Specific Questions Arising from
Comparisons Between Species!
Specific Questions Arising from
Comparisons Between Species!
Do species comparisons produce merely a series of
adaptive stories ?!
  Do species comparisons simply demonstrate that
animals can live where they do?!
  Yes, the species comparative approach necessarily
shows this, but again, this need not be a selfanswering ( trivial ) question!
  The question is more attractive when rephrased as:
What physiological mechanisms allow animals to
live where and how they do? !
  Does the approach based on species comparisons
have adequate analytical paradigms?!
 
!Spring 2010
Do species comparisons produce merely a
series of adaptive stories ?!
  Do species comparisons simply demonstrate
that animals can live where they do?!
  Does the approach based on species
comparisons have adequate analytical
paradigms?!
 
 
 
Topic 1 – 4!
All scientists need paradigms!
As knowledge increases, paradigms change
(essential part of the success of science is that it is
self-correcting)!