Donald M. Broom

1
Donald M. Broom Centre for Animal Welfare and
Anthrozoology Department of Veterinary
Medicine University of Cambridge, U.K.

dmb16_at_cam.ac.uk


Eco-Physiologogy Lecture 800 9.00 Tuesday
. Instructor Dalia Fouad, Assistant professor
of Department of Zoology, Faculty of
Science Office 24 building 21 Phone
1503 Email dibrahim_at_KSU.edu.sa   Office
Hours 1200 1.00 Tuesday Required
TextMcNab, B. K. 2002. The Physiological Ecology
of Vertebrates A View from Energetics. Cornell
Univ. Press, New York, NY. 576 pp. Required
Journals (J. Experimental Zoology - J. Exp.
Biol- Journal of Animal Science ). Additional
Readings Karasov, W.H., and C. Martinez del Rio.
2007. Physiological Ecology How Animals Process
Energy, Nutrients, and Toxins. Princeton Univ.
Press, Princeton, NJ. 741 p. Robbins, C. T. 1994.
Wildlife Feeding and Nutrition, 2nd ed. Elsevier
Press. 353 p. Schmidt-Nielsen, K. 1997. Animal
Physiology Adaptation and Environment, 5th
edition. Cambridge Univ. Press, New York. 602
p. Speakman, J.R. 1997. Doubly Labelled Water
Theory and Practice. Chapman and Hall,
London. Wilmer, P., G. Stone, and I. Johnston.
2000. Environmental Physiology of Animals.
Blackwell Science, Palo Alto, CA. Sibley, R.
M., and P. Calow. 1986. Physiological Ecology
of Animals An Evolutionary Approach.
Blackwell Sci. Publ., Palo Alto. 179 p. (out of
print) Stevens, C. E., and I. D. Hume. 1995.
Comparative Physiology of the Vertebrate
Digestive System. 2nd edition. Cambridge Univ.
Press, New York. 400 p.

2
Donald M. Broom Centre for Animal Welfare and
Anthrozoology Department of Veterinary
Medicine University of Cambridge, U.K.

dmb16_at_cam.ac.uk



Eco-Physiologogy The required course textbook is
Willmer, Stone Johnston. 2005. Environmental
Physiology of Animals 2nd edition, Blackwell
Science. ISBN1-4051-0724-3. Although the 2nd
edition of the book has been published in 2005,
and it is preferred textbook for this course, a
considerable portion of lecture materials can
still be found in the 1st edition. Therefore it
is acceptable to use the 1st edition if you can
find a used copy. Sufficient copies of the new
2nd edition text are available in the library or
Bookstore. A considerable portion of the lecture
materials will be related, but not limited to the
textbook.
3

Eco-Physiologogy Study of interactions between
organisms and their physical environment.Emphasiz
es individuals, not groups like populations or
communities.The intersection between ecology and
physiology (study of how organisms
function).Also mostly equivalent to
"ecophysiology."
4

• Eco-Physiologogy
• Two themes
• Homeostasis maintenance of constant internal
  conditions in varying environments
• Adaptation of organisms to specific environments
• Animals have many needs and these can be
  investigated.

5

• Three big problems
• Obtaining energy and nutrients
• Maintaining temperature
• Obtaining and holding onto water
• Energy
• All organisms require energy to live and
  reproduce
• Heterotrophs acquire energy from organic
  material, live or dead
• most animals feed on living organisms
• decomposers (fungi, some animals) feed on dead
  organisms

6
Energy All organisms require energy to live and
reproduce Heterotrophs acquire energy from
organic material, live or dead most animals feed
on living organisms decomposers (fungi, some
animals) feed on dead organisms
7

• Autotrophs acquire energy from sunlight or
  chemicals in the environment.
• Chemosynthetic autotrophs
• obtain energy from inorganic chemicals like
  methane or hydrogen sulfide.
• sea-vent bacteria.
• Photosynthetic autotrophs
• combine energy from sunlight and CO2 to make
  sugars
• many bacteria, some protists (algagae), and
  nearly all plants.

8
Water contains dissolved substances
solutes Water moves from regions of low solute
concentration to high concentration Movement of
water across a membrane is osmosis
.
Water
9
High solute concentrations attract water with a
force known as osmotic potential.

10

Water moves freely across cell membranes Relative
to the outside environment, a cell can
be hypo-osmotic having a lower solute
concentration than the environment hyperosmotic
having a higher solute concentration than the
environment iso-osmotic having the same solute
concentration as the environment
If left unchecked, osmosis will lead to
equilibration of solute concentrations in and
outside of cells.HYPO-ISO-HYPEROSMOTIC

11

For organisms, the challenge is maintaining
proper concentrations of solutes in cells
(homeostasis). semipermeable membranes some
molecules cannot pass active transport moving
molecules across the membrane, requires energy
12
Water Acquisition in Animals Wet
environments drinking absorbing from the
environment (amphibians) Dry environments metabo
lic water (C6H12O6 6O2 ? 6CO2 6H2O) water in
food sources (insectivores) water reabsorbed in
digestive/excretory systems.
13
Water Balance in Marine Animals Marine
invertebrates maintain iso-osmotic internal
solute concentrations equal to seawater Marine
fish are hypo-osmotic compared to seawater.
they gain solutes and lose water solutions const
ant drinking secreting salt into the water.
Sharks and rays have high concentrations of
solutes in their blood, making them iso-osmotic
compared to seawater. To maintain proper
concentrations of ions, sharks keep urea in the
bloodstream.


14

• Water Balance in Freshwater Fish
• Freshwater fish are hypo-osmotic compared to
  water and absorb water continuously.
• They excrete large quantities of diffuse urine
  while actively retaining salts.
• Organisms in variable environments adjust their
  solute levels based on the salinity of the water.

15

Temperature
.
16

At hot temperatures biological processes speed
up proteins and other organic compounds may break
down At cold temperatures ice crystals may damage
or destroy cells life processes slow or stop.
17

Homeothermic organisms maintain constant body
temperature (birds and mammals) Poikilothermic
organisms have varying body temperature, in
response to external temperatures (all other
animals) BUT poikilothermic animals may regulate
their body temperature Endothermy body heat
generated internally Ectothermy body heat
generated externally Most ectotherms regulate
their body temperature by basking moving between
shade/sun being active at certain times of
day Endothermy requires a lot of
energy Alternative is torpor condition of
lowered body temperature and activity
18
HOW DO WE FIND OUT FROM ANIMALS WHAT THEY NEED?

19

• Countercurrent Circulation
• Reduce rate of heat loss to the environment by
  creating a temperature gradient.
• Heat is transported from arterial blood leaving
  the body to venous blood returning to the body.

20
Each organism has an optimum
environment. Optimum narrow range of
environmental conditions to which an organism is
best suited.
Price elasticity of demand slope at z
.
21
2) A desert lizard species (a
Chihuahuan whiptail) . What adaptations are
necessary (activity time, place to spend hot
days, physiological adaptations to water
limits)? We can consider physiological ecology to
be the study of adaptations to the physical
conditions of the environment. A species has
tolerance to some range of each abiotic
factor, i.e. temperature, water availability,
salinity, nutrient avail- ability. Here is a
generalized curve of distribution

• Well consider each of these approaches to
  eco-physiology basically in the next order
  through the semester.
• ECHO-PHYSIOLOGY
• By example, consider the adaptations necessary
  for success
• In a fresh water fish (a rainbow trout)
• Where did fish evolve? Under what physical
  conditions?
• Are these the same conditions as those where
  rainbow trout
• are found today?

22

.
23

• In the range labeled as OPTIMAL ENVIRONMENT
• survival, growth, and reproduction can occur
• more individuals are found
• BUT
• In sub-optimal environments (zones of stress)
• individuals may survive, but growth rate will be
  lower
• reproduction is impossible or unlikely
• fewer individuals are found

24
The concept of a tolerance limit is embodied in
Leibigs law of the minimum. It states Under
stable conditions, the essential constituent most
closely approaching the minimum for survival
(and/or reproduction) tends to limit the
occurrence of a species. An alternative
statement, stolen from a WWII movie A chain is
only as strong as its weakest link. (Hayakawa
via Cavett) When conditions are varying, this
law doesnt work very well. What was limiting
at one time may be abundant only a short time
later. The law of the minimum neglects the
possibility that there is too much of something
salt, calcium, temperature, water
25
That led to the Shelford law of tolerance. In a
paraphrase A species will be found only
where its needs are met and its tolerances
are not exceeded.
26

• Animal Physiology
• Study of how animals function
• Importance
• For basic understanding of physiology since human
  are part of the animal kingdom
• Important practical applications for health and
  disease, management
• Mechanism and Origin Physiologys two central
  questions
• What is the mechanism by which a function is
  accomplished?
• How did the mechanism originate?

27
The importance of physiology
The study of mechanism How do modern day
animals carry out their functions?? study or
organ, cell functions and metabolism The study
of origin Why do modern-day animals possess the
mechanisms they do? ? they inherited it from
ancestors it was beneficial ?adaptation through
selection Mechanism and adaptative significance
are distinct concepts that do not imply each
other Adaptation can be achieved through
different mechanisms. Physiological mechanisms
can be explain from a combination of evolutionary
origin, environmental adaptations
.
28

• Animals
• Molecules forming an animal are constantly
  changing
• The structure of an animal (organ system)
  persists through time
• The cells are exposed to the internal environment
• The internal environment might be permitted to
  change with the external environment ? conformity
• The internal environment might be kept constant
  despite varying external environments ?
  regulation

29
Topics of Discussion
Animals and response systems are subject to
challenges from their environment
pathogens,
tissue damage,

• State the main ideas youll be talking about

attack or threat of attack by a conspecific or
predator,
other social competition,
complexity of information processing in a
situation where an individual receives excessive
stimulation,
lack of key stimuli such as a teat for a young
mammal or those associated with social contact
for a social animal,
lack of overall stimulation.
In general, inability to control interactions
with their environment.
30
How well can our domestic animals adapt to the
conditions that we impose upon them?
At the individual level, adaptation is the use of
regulatory systems, with their behavioural and
physiological components, to help an individual
to cope with its environmental conditions.
Animals can adapt better if their needs are met.
31
What are the limits to adaptation?
Where coping means having control of mental and
bodily stability, an individual attempting to
cope may fail to do so.
For example, it may be difficult or impossible to
cope with extreme external
temperature, pathogen
multiplication, high predation
risk or difficult social conditions.
Body state may be displaced to outside the
tolerable range and death may follow.
The term stress is best limited to situations in
which control systems are over-taxed and the
individual is harmed. Stress implies inability
to adapt or to cope. The term stress is
scientifically unusable if it includes beneficial
stimulation.
32
Homeostasis internal constancy critical to
maintain proper function State of constancy
within the internal environment of a living
organism A dynamic process constant adjustment to
counteract changes Central principle of
physiology Claude Bernard recognized the
constancy of the internal environment Constancy
of the internal environment is the condition for
free life Walter Cannon (1871-1945)
introduced the term homeostasis coordinated
physiological processes which maintain most of
the constant states in the organism.
33
How does an organism maintain homeostasis? Regula
tion maintaining different attributes of the
internal environment at relatively constant
levels Requires a regulatory mechanism Sensor -
Detects changes (disturbances) in the internal
environment Effector - Performs an activity that
compensates for the change Controller/Integrator
- controls activity of the effector based on
information from the sensor
34

• Homeostasis is critical to mammals, but it is not
  important for survival in some other groups
• Regulation and conformity have their own
  advantages/disadvantages
• Regulation Costs energy but permits cells to
  function in a constant internal environment
  despite changing external conditions
• Conformity Cells are subjected to changes when
  external environment changes. However, if they
  survive it, the energy cost is minimal.

35
When coping is successful and problems are absent
or minor, welfare is good.
Good welfare is generally associated with
feelings of pleasure or contentment. Like bad
feelings, such as pain or fear, good feelings are
a biological mechanism which has evolved.
A feeling is a brain construct, involving at
least perceptual awareness, which is associated
with a life regulating system, is recognisable by
the individual when it recurs and may change
behaviour or act as a reinforcer in learning.
Suffering occurs when one or more negative
feelings continue for more than a few seconds.
36

• Responses to changes
• Acute responses responses within minutes
• Chronic responses long term changes to the
  physiology
• Acclimation physiological responses to small
  changes in the environment.
• similar changes induced in laboratory settings.
• Acclimatization responses to a larger change in
  the environment (ex winter and summer)

Time in the lives of animals 1- physiological
responses to change in external environment

physiological/biochemical/anatomical change in an
individual organism resulting to chronic exposure
to new conditions in the natural environment.
37
Phenotypic plasticity phenotypic changes that
an individual (single genotype) can undergo with
changing environment
2- internally programmed changes of physiology
Internally programmed changes genetically
programmed can be due to development or to
biological clocks - development Hb
expression - biological clocks - daily
rhythm - seasonal rhythm ..
38
Differences Acclimation/Acclimatization changes
occur in an individual changes are generally
reversible(Acclimatization Acclimatization is
physiological adjustment during an organisms
lifetime. Short-term, often reversible.NOT
heritable.Example Increased hemoglobin in
athletes who train at high altitude.
39

Adaptation changes occur over multiple
generations changes not generally
reversible(Adaptation Adaptation is evolution by
natural selectionGenetic changes in a population
over many generations.Populations adapted to
particular environmental conditions are termed
ecotypes.
40
A Characteristic is Adaptive If It confers a
maximal probability of survival and successful
reproduction in comparison with available
alternative states. Qualifiers Characters are
adaptive only in specific environmental
contexts. Adaptive ? optimum
A need is a requirement, which is part of
the basic biology of an animal, to obtain a
particular resource or respond to a particular
environmental or bodily stimulus.
41

The Effects of Environmental Factors on Animal
42

• Thermal Regulation
• For an organism to maintain a (somewhat)
  constant body temperature
• heat gained by the body heat losses.
• Heat exchange takes place with the surrounding
  environment through four means
• - conduction,
• - convection,
• - radiation (reradiation)
• - evaporation.

43

• Because air has a lower specific heat than water,
  and absorbs less solar radiation before rising in
  temperature, terrestrial
  animals are subject to more radical changes in
  their thermal environment than are aquatic
  animals.
• Aquatic animals live in a more stable energy
  environment, but generally have a lower tolerance
  to temperature changes.

44
Thermal balance The heat balance of an organism
is described by Htot Hc /- Hcd /- Ht /- He
/- Hm Where Htot is the rate of metabolic heat
production Hc is the rate of heat gained or lost
through convection Hcd is the rate of heat gained
or lost through conduction Ht is the rate of heat
gained or lost through radiation He is the rate
of heat lost through evaporation Hm is the rate
of heat storage in the body through metabolic
processes
45
A thermal model of the animal body (To maintain
core body temperature, the animal must balance
losses and gains. Thermal balance in the core
of the animal is influenced by heat produced by
metabolism heat stored heat flow to the skin as
affected by the thickness and conductivity of
fat, fur, hair, feathers, and scales heat flow
to the ground and heat lost by evaporation.
46

• Physiologically, animals can be divided into 3
  groups based on how they control body
  temperature
• Homeotherms - those that maintain a fairly
  constant internal temperature regardless of
  external temperature by means of endothermy (they
  use their own metabolic heat production) e.g.
  birds and mammals.
• By producing heat through metabolism, homeotherms
  are less constrained by thermal environments.
• The main disadvantage of homeothermy is a higher
  food requirement to maintain metabolism.
• Body size is also an important consideration
  because metabolic rate is proportional to the
  0.75 power of body mass
  (metabolic rate varies
  inversely with body weight)
• .

47
General resting metabolic response of homeotherms
to changes in ambient temperature. .
Hypothermia
Hyperthermia
48
Homeotherms The basal metabolic rate of various
mammals, measured by oxygen consumption, is
proportional to body mass raised to the (0.75)
power.
The higher the mass, the lower the
oxygen consumption/metabolic rate
49
Homeotherms and Poikilotherms
homeotherms
40
30
Tb (C)
20
poikilotherms
(body temp)
10
10
20
30
40
Ta ( C)
Environmental Temp
50
Can live in a variety of habitats Can respond
rapidly to environmental stimuli (Smaller
animals react more rapidly since their metabolic
rate is higher)
Homeotherms Advantages warm-blooded
vertebrates- birds mammals Maintain constant
Tb Endothermic (metabolism is source of body
heat).Normal Tb range is 35-42 degrees C
51
Rapid and Efficient Delivery of Oxygen to Fuel
Metabolism In birds and mammals cardiovascular
and respiratory systems have evolved to meet need
for enhanced exchange, transport and delivery of
respiratory gasses (oxygen and carbon
dioxide)
52

• Homeotherms adaptations to control heat loss
  include
• Panting (evaporation) or gular fluttering
  
  (vibrating membrane in birds)
• Counter current system outgoing blood into an
  appendage is cooled by a parallel blood vessel
  containing incoming blood.
• Thermal windows e.g. large ears in desert fox
  radiate heat.
• Insulation fur or blubber layer.
• Shivering in increase in muscle action produces
  metabolic heat.
• Non shivering thermogenesis metabolism of
  brown fat produced heat.
• Burrowing or other behavioral adaptations.

53

Starvation and effects of extreme temperature.
Starvation occurs when there is a shortage of
nutrients or energy such that the animal starts
to metabolise functional tissues rather than food
reserves. (Broom and Fraser 2007).
Work by Clive Phillips and colleagues (Agenäs et
al 2006) have provided some useful measures for
cattle. More measurements of starvation are
needed. Also, methods of management that do not
have a serious risk of starvation should be
developed.
The effects of extreme temperature and their
effects on animal also require study and changes
in management practice.
54

• Poikilotherms those that allow their body
  temperatures to vary with ambient temperature
• e.g. invertebrates, fish, amphibians, and
  reptiles.
• Poikilotherms maintain body temperature through
  ectothermy (they use sources of heat energy such
  as solar radiation and reradiation rather than
  metabolism)
• Ectothermy has the advantage of limiting
  metabolic costs associated with maintaining body
  temperature hence, less food is required and
  more energy can be allocated to biomass
  production.
• These animals are not limited to a minimum size.
  
• However, they are limited to activity only
  during those times when the temperature is
  adequate to support their functions Active
  Temperature Range - ACT

55

• These factors mean that poikilotherms can
  colonize low food environments
• e.g. deserts
• The size of poikilotherms can also be small (e.g.
  insects)
• and they are not limited by shape (e.g. snakes)
• but they may not be able to absorb enough heat to
  maintain a very large body
• So perhaps some dinosaurs were homoeothermic?
• Or warmed in some other way (gut flora in
  diplodocus or brontosaurus?)
• Or perhaps very large sizes limited heat loss?

56

Poikilotherms can survive within a range of
temperatures of thermal tolerance The ranges
of thermal tolerance can change
(within limits)- acclimatization A
poikilotherm can adjust to slow changes in
temperature but a major change can cause
thermal shock
57

• Frogs and reptile can bask in the sun to
  increase their temperature heliothermism
• Amphibians may loose heat through permeable skin
  (evaporation)
• So basking amphibians, by controlling the amount
  of body exposed to air,
• and how much is immersed in water
• can also control evaporation
• The temperature of water can also warm, or cool,
  amphibians

58

• Reptiles do not have a permeable skin like
  amphibians evaporation reduced
• But by panting some heat can be lost by
  evaporation
• also by eye bulging
• Heliothermism is a major way for reptiles to
  control heat
• By changing their orientation to the sun, and the
  surface area exposed to direct sunlight
• (e.g. expanding/contracting ribs and flattening
  body)
• they can alter heat absorption proportional
  control
• they can also burrow or possibly change color

.
59

• Poikilotherms
• Adaptations to low temperatures
• supercooling - use of antifreeze (e.g.
  glycerol)
• Some insect species can actually freeze (90)
• diapause- a resting stage
• cessation of feeding, growth, mobility, and
  reproduction

60

• Heterotherms - those animals that sometimes
  regulate their body temperatures and sometimes do
  not.
• e.g. bees
  and bats. They exhibit characteristics of both
  endothermy and ectothermy.
• Flying insects are essentially ectothermic when
  at rest and endothermic while in flight.
• Similarly, true hibernators and endotherms that
  enter daily torpor (bats) can be considered
  heterotherms
• because their body temperature decreases during
  these quiescent periods.
• Other mechanisms for maintaining heat balance
• Homeotherms that become heterothermic
• torpor (temporary condition resulting in
  reduction in respiration and loss in power and
  locomotion)
• hibernation (winterdormancy)
• estivation (summer dormancy e.g. ground
  squirrels).

61

• Moisture Environment
• The mobility of animals allows them to seek more
  favorable habitats during periods of suboptimal
  moisture conditions.
• They also possess a protective outer covering
  that protects against passive water loss.
• The mechanisms involved to rid the body of
  excess water and solutes or to conserve them
  (water balance)
• are much more complex in animals than in plants.
• e.g. contractile vacuoles of protozoans
• to gills,
• to the complex kidney and urinary systems of
  birds and mammals.
• Animals also conserve water by tolerating
  hyperthermia, controlling respiration, or
  possessing
• various behavioral or anatomical characteristics
  (e.g., estivation, salt glands, etc.)
• ).

62

• Organisms living in marine and brackish
  environments have cells that are more
• dilute than seawater and are hypoosmotic.
• They must inhibit the loss of water by osmosis
  through the body wall and prevent an accumulation
  
• of salts in the system.
• Some use active transport and excrete sodium and
  chlorine by pumping ions across membranes
• of special cells in the gills.
• Others are isoosmotic and maintain the same
  osmotic pressure as their surrounding
• aquatic environment.
• Fresh water aquatic organisms are hyperosmotic
  (their body fluids are osmotically
• more concentrated than the surrounding water)
  and need to prevent osmotic inflow.
• In freshwater fish, intake of water is mainly
  through the gills and excess water is eliminated
  through urine.

63

• Heterotherms - those animals that sometimes
  regulate their body temperatures and sometimes do
  not.
• e.g. bees
  and bats. They exhibit characteristics of both
  endothermy and ectothermy.
• Flying insects are essentially ectothermic when
  at rest and endothermic while in flight.
• Similarly, true hibernators and endotherms that
  enter daily torpor (bats) can be considered
  heterotherms
• because their body temperature decreases during
  these quiescent periods.
• Other mechanisms for maintaining heat balance
• Homeotherms that become heterothermic
• torpor (temporary condition resulting in
  reduction in respiration and loss in power and
  locomotion)
• hibernation (winterdormancy)
• estivation (summer dormancy e.g. ground
  squirrels).

64

• Drought can alter food selection in herbivores,
  result
• in outbreaks of herbivorous insects,
• alter mortality and fecundity, and slow insect
• development.
• Excess moisture spreads disease among both
  animals
• and plants by promoting
• the spread of fungi, bacteria, and viruses.

65

• Homeotherms
• maintain relatively constant body
  temperature.Truly effective homeothermy is only
  achieved by endotherms
• like birds and mammals, who use metabolic heat to
• warm the whole body.
• Poikilotherms
• don't regulate body temperature it varies
  directly with

66

• Ectotherms
• rely mostly on external sources of energy
  behavioral
• thermoregulation (basking in warm sunlight,
  etc.).

67

• Surviving extreme cold
• In cold conditions, endotherms increase their
  metabolic
• rate to stay warm.However, in extreme cold they
  may run out of energy, or it
• may not be possible to keep warm.Some animals
  survive cold and conserve energy by going
• into a dormant state with drastically reduced
  metabolic rate
• and body temperature. Torpor - lasts several
  hoursHibernation - lasts the entire winter

68

• Temperature Relations
• Temperature is a very important environmental
• variable for both animals and plants.Organisms
  have a specific range of
• temperature in which they can grow.An important
  reason for this is the activity of enzymes, which
• is highly sensitive to temperature.
• Metabolic heating
• HmetALL living things generate some heat as a
  by-product
• of metabolism.Yes, even insects, plants, fungi,
  bacteria.Second law of thermodynamics.Only a
  few groups generate lots of heat and

69
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70

• Animals may either defend a fairly constant
  temperature by
• recruiting biochemical mechanisms
• of heat production and utilizing physiological
  responses
• geared toward modifying heat loss and heat gain
  from the
• environment, or utilize biochemical modifications
  to allow
• for physiological adjustments to temperature.
  Biochemical
• adaptations to temperature involve alterations in
  protein
• structure that compromise the effects of
  increased temperatures

71

• Temperature has acted to shape the responses of
  animal
• proteins in manners that generally preserve
  turnover rates
• at animals' normal, or optimal, body
  temperatures.
• Physiological responses to cold and warmth differ
  
• depending on whether animals maintain elevated

72

• Examples of biochemical responses to temperature
  in
• endotherms involve metabolic uncoupling
  mechanisms
• that decrease metabolic efficiency with the
  outcome of
• producing heat,whereas ectothermic adaptations
  to
• temperature are best exemplified by the numerous
• mechanisms that allow for the tolerance or
  avoidance of
• ice crystal formation at temperatures below 0C.
  

73
Related Articles Temperature Relationships
From Molecules to Biogeography.Behavioral
Thermoregulation in the Cold.Thermogenic
Responses to Prolonged Cold Exposure Birds and
Mammals.Sleep, Thermoregulation, and Circadian
Rhythms.Integrated Physiological Mechanisms of
Exercise. Performance, Adaptation, and
Maladaptation to Heat Stress.
74

• Light Environment
• The daily and seasonal changes in the light
  environment trigger daily
• and seasonal responses in the activities of
  animals.
• An innate rhythm of activity and inactivity
  covering approximately
• 24 hours is characteristic of all living
  organisms except bacteria.
• Because these rhythms approximate, but seldom
  match, the periods
• of Earths rotation, they are called circadian
  rhythms.

75
Circadian rhythms have a strong genetic component
and are Transmitted from one generation to
another. They are little affected by
temperature changes, are insensitive to a great
variety of chemical inhibitors, are not learned,
and are not imprinted on the organism by the
environment. But they are effected to exposure
to daylight. They influence not only the time
of physical activity and inactivity but also
physiological processes and metabolic rates.
76

• The circadian rhythms and their sensitivity to
  light are
• mechanisms underlying the biological clock, the
• timekeeper of physical and physiological activity
  in living things.
• Operation of the clock in mammals involves the
  hormone
• melatonin.
• More melatonin is produced in the dark than in
  the light,
• so that the amount produced is a measure of
  changing
• daylength.

77

• Heterotherms - those animals that sometimes
  regulate their body temperatures and sometimes do
  not.
• e.g. bees
  and bats. They exhibit characteristics of both
  endothermy and ectothermy.
• Flying insects are essentially ectothermic when
  at rest and endothermic while in flight.
• Similarly, true hibernators and endotherms that
  enter daily torpor (bats) can be considered
  heterotherms
• because their body temperature decreases during
  these quiescent periods.
• Other mechanisms for maintaining heat balance
• Homeotherms that become heterothermic
• torpor (temporary condition resulting in
  reduction in respiration and loss in power and
  locomotion)
• hibernation (winterdormancy)
• estivation (summer dormancy e.g. ground
  squirrels).

78

• The signal for a response is critical daylength.
  
• Many organisms possess both long-day and
  short-day responses.
• Because the same duration of light and dark
  occurs
• twice a year, the distinguishing cue is the
  direction
• from which the critical daylength is approached.
• For some organisms, tidal and lunar rhythms are
  of
• greater importance than light-dark cycles.
• E.g. marine species horseshoe crab and coral
  spawning

79
Onset of running wheel activity for one flying
squirrel in natural light conditions throughout
the year. The graph is the time of local sunset
through the year.
80
The seasonal course of hormonal levels during the
annual cycle of the white-tailed deer and its
relationship to antler growth.
81

• Animal needs differ little among vertebrates and
  invertebrates
• Animals require mineral elements and 20 amino
  acids, of which 14 are essential.
• The ultimate source of most of these nutrients
  is plants for this reason, the quantity and
  quality of plants affect the nutrition of 1ary
  consumers.
• When the amount of food is insufficient,
  consumers may suffer from acute malnutrition,
  leave the area or starve.
• When food is of low quality, it reduces
  reproductive success,
  health and longevity.

82

• The need for animals to derive their energy from
  organic carbon compounds presents them with a
  potentially wide range of food items.
• The ultimate source of these organic compounds is
  plants.
• However, animals differ by the means they use to
  acquire these compounds.

83

• Herbivores utilize plant material and are primary
  consumers.
• Food is generally plentiful, but the diet is
  constrained by low protein levels
  (plants are low in proteins and
  high in carbohydrates, much of which is in the
  form of cellulose and lignin in cell walls) and
  the relative indigestibility of cellulose in
  plant materials.
• Adaptations in herbivores are aimed at increasing
  the digestion and assimilation of plant materials
  and often involve complex digestive systems with
  a multi-part stomach inhabited by anaerobic
  bacteria and protozoans that function as
  fermentation vats.

84

• e.g. ruminants - plant matter is chewed and then
  swallowed
• the food enters the rumen where bacteria ferments
  plant material
• the fermented plant material is regurgitated
  (cud) and re-chewed and re-swllowed
• - The fermenting bacteria break down
  carbohydrates and also produce B vitamins,
  the enzyme cellulase, and amino-acids
• e.g. coprophagy animals such as rabbits produce
  green feces (after processing by microorganisms
  in the caecum)
• These pellets are high in protein and lower fiber
• These are re-digested and dry, high fiber, low
  protein pellets are produced.

85

• Omnivores utilize both plant and animal tissues.
  Food habits of many omnivores vary with the
  seasons, stages in the life cycle, and their size
  and growth rate.
• Carnivores feed on animal tissue and are
  secondary consumers.
• Carnivores are not usually constrained by diet
  quality (animal tissue is high in fat and
  proteins which they use as structural building
  blocks)
• rather, their major constraint is related to
  obtaining sufficient amounts of food through
  capture of elusive prey. Adaptations in
  carnivores, therefore, are related to increasing
  the success of prey capture.

86

• Detrivores are detrital feeders, that is, they
  feed on dead plant and animal matter. Like
  herbivores, they depend heavily on mutualistic
  relations with microorganisms to aid in the
  breakdown of cellulose and lignin.
• As the nitrogen content of their food increases,
  assimilation of plant material improves,
  increasing growth, reproductive success and
  survival.
• Nitrogen is concentrated in the growing tips of
  roots and plants so nitrogen content may be
  highest in spring
• - So production of young often coincides with
  spring

87

• In general, sodium, calcium, and magnesium are
  known to affect the distribution, behavior,
  fitness, and, possibly,
  the cyclic population
  patterns of some animals. e.g. African
  elephants, white-tailed deer, and moose.

88

• Each type of food used by animals presents a
  unique set of constraints related to the ability
  of the organisms to acquire and assimilate the
  food item.
• These constraints directly influence physiology,
  morphology, and behavior of the species.

89
These characteristics allow each species to
exploit a given food resource, but also
function to restrict the ability to exploit
other, different food sources.
90
Respiration The avian lung has the greatest
known relative gas exchange surface area and
thinnest barrier to oxygen diffusion, and in
combination with anatomical specializations is
the most efficient lung of all air-breathing
vertebrates at oxygen extraction (from Quick and
Ruben 2009)
91
Separate nutrient and waste Streams
92
Air Sac System
93
How Breathing Works
94
Bellows Move Air

• Lungs dont move
• No diaphragm
• Air sacs fill body cavity
• Ribs as a bellows
• Unique thigh supports abdominal air sacs

95
Sternum moves down, Ribs move forward during
Inspiration
Muscles to uncinate processes may enable
breathing when sternum cannot be depressed
(Claessens 2009)
96

• Adaptations for Hot Conditions avoiding
  Hyperthermia
• Physiological adaptations
• Cardiovascular changes-dilate blood vessels to
  send more blood to skin surface
• also increased cardiac output
• Evaporative coolingprimary way

97

• Adaptations for Hot Conditions avoiding
  Hyperthermia
• Physiological adaptations
• Birds
• no sweat glands
• evaporate water over lungs, air sacs
• and gular pouch (some)
• accomplished by panting, gular fluttering

98
Prolonged exposure to high ambient temperatures
. TO Lower Body Temperature Hyperthermia
Hyperventilation vasodilation
Increased
cardiac output Evaporative cooling
Rapid exchange of air through air sacs



More blood sent toSkin surface Feet, wings,
gular area

99

• Adaptations for Hot Conditions avoiding
  Hyperthermia
• Physiological adaptations
• Increase water intake
• Seek cool places- shadows, vegetation to reduce
  heat gain

100
Additional References Claessens, L. P. A. M.
2009. The skeletal kinematics of lung ventilation
in three basal bird taxa (emu, tinamou, and
guinea fowl). J. Experimental Zoology
311A586-599. Quick, D. E. and J. A. Ruben. 2009.
Cardio-ppulmonary anatomy in theropod dinosaurs
implications from extant archosaurs. J.
Morphology 2701232-1246. OConnor, P. M. and L.
P. A. M. Claessens. 2009. Respiratory evolution
in sauropsids progress and new approaches. J.
Experimental Zoology 311A549-550. Sereno, P. C.
et al. 2008. Evidence for avian intrathoracic air
sacs in a new predatory dinosaur from Argentina.
PLOS one. 3(9). E3303. Scott, G. R. 2011.
Elevated performance the unique physiology of
birds that fly at high altitudes. J. Exp. Biol.
2142455-2462