Physiology and
Behaviour I
Dr Mike Wride
School of Natural Sciences
Zoology Department
email: [email protected]
Two Lectures
• Physiology and Behaviour I:
Physiological mechanisms - hormones and
behaviour, the effects of the environment
• Physiology and Behaviour II: Drive
and motivation; Behavioural responses to
change in environment:
Text Books
• David McFarland (1999) Animal Behaviour
3rd Ed. Chapters 15 and 16
• Chris Barnard (2004) Animal Behaviour:
Mechanism, Development, Function and
Evolution. Chapters 3.3, 4 and 5
• Principles of Animal Behaviour (2009). 2nd
Ed. Lee Alan Dugatkin Chapter 3
Outline of Lecture
• Physiological mechanisms - hormones and
behaviour
• Homeostasis
• Environmental influences on behaviour
• Conformers and adaptor thermoregulation, thirst, energy and
nutrients
• Effects of stress on behaviour
Physiological Mechanisms
• The “nuts and bolts” of behaviour
• Two major mechanisms
• Nervous System - “organised”
behaviour - coordiantion/
integration of sensory and motor
systems in the organism
• Hormones - endocrine system
affects sensitive tissues at distant
sites within the body
Hormones and Behaviour
Dugatkin p 81, Fig 3.7
endocrine cells and target
cells
Complex Effects of
Hormones
Dugatkin, p83, Fig 3.9
Hormones can trigger a new behaviour or modify an existing
behaviour or they can ‘prime’ the organism to respond to a
particular environmental situation that might arise in the future
Testosterone and
Aggression
Dugatkin p84, Fig 3.10
Effect of Hormones on
Behavioural Systems During
Development
Dugatkin, p 85, Fig 3.11; p86 Fig 3.13
in utero position and
subsequent adult behaviour
Dugatkin p 87, Fig 3.14, 3.15
Changing Environments
• Animals initiate steps to deal with physical
demands of changing environments
• To maintain survival and ability to reproduce
• Two principles:
• Tolerance - extent to which
extremes can be tolerated (e.g. temp,
sailinity)
• Acclimatization - physiological
adaptation to changing environments
Homeostasis and
Behaviour
• Homeostasis:
maintenance of internal
environment of an animal
• “An animal that is able to regulate its internal
environment (maintain homeostasis), in the face of
fluctuations in the external environment, has
greater freedom to exploit a variety of potential
habitats” Claude Bernard (1859)
The Feedback Principle
of Homeostasis
p265 McFarland; Fig 15.4: feedback principle in
a simple thermostatic electric heater
2 Types of Animals
• Conformers: change internal environment
to match external environment
• Regulators: maintain internal environment
at a steady state
Internal sensors monitor the internal state of the
body and initiate appropriate responses to return the
body to the steady state when deviations from it
occur i.e. a responsive approach....but, some
regulation is pro-active
Thermoregulation
• Most animals have optimal body temperature
• Function most efficiently at this temperature
Reduction in
temp
Metabolism slows,
muscle activity diminishes,
animal becomes torpid
Body biochemistry/
processes unviable
Increase in
Temp
Approaches in response
to change in internal body
temperature
• Employ specialised physiological mechanisms
• Change behaviour
• both depend on thermoreception - detecting
internal and external body temperature
Responses of Invertebrates
to reduction in temp
• Some invertebrates (cold blooded -
conformers): reduce their activity when
external temperature falls
• Other invertebratess (e.g. common
woodlouse, millipede) maintain a body
temperature higher than the environment
Responses of Vertebrates
to Reduction in Temp
• Warm blooded (endotherms) -
shivering, increased food intake (to create
more heat)
• Cold blooded (exotherms)- gain heat
from external sources (e.g. sun)
• May change colour e.g. Desert iguana
Dark in am and gets
lighter as the day
progresses
Solutions to Increase in
Temp: Overheating
• Cooling mechanisms required
• Conduction: direct loss of heat
• Convection: blood flow to periphery
• Radiation: proportional to temp
difference between internal and external
• Evaporation: energy associated with
water loss
Feather Movement in
Doves
p263 McFarland; Fig 15.1
Examples of control of Heat
Loss by Changes in Behaviour
• Fiddler crabs, ground squirrels - and
other burrowing animals - make sorties
between cool burrows and warm
external environment to cool off
• Panting in birds and mammals - when
potentially lethal temperature
approaches
• Namib desert lizard - burrows into the
sand when midday temp goes above
40oC
Behaviour of a
Dehydrated Camel
p264 McFarland; Fig 15.2
Behaviour of a
Burrowing Lizard
p264 McFarland; Fig 15.3
Sand dunes have
fluctuating surface
temp. Lizard under
surface when surface
temp too hot or too
cold
Shaded blocks -active
periods of lizard
Water Homeostasis
• Two major mechanisms:
• Water conservation
• Thirst
Extracellular Thirst:
Hypovolaemia
p268 McFarland, Fig 15.7
Water Conservation
Mechanisms
ADH - water retention
P268 McFarland, Fig 15.8
Energy and Nutrients
• Process of digestion and pattern of eating
often related
• Amount of sodium is very important for
maintaining homeostasis
• Animals have an innate sodium appetite, but
can also learn and remember the sources
of sodium
• Salt depleted rats remember and return to
a source of sodium in a maze
Feeding Behaviour
• Rats deficient in thiamine show preference for
novel food
• If novel food contains thaimine, rat continues to
eat this food
• Adaptation to rapidly exploit new sources of
nutrients
• Rat can bypass ‘old’ food in stomach by digesting
some of the new food to assess the
consequences of ingesting the new food
Stress
• Can be considered to be anything that
poses a threat to homeostasis
• Both internal and external stimuli can cause
stress - stressors (e.g. haemorrhage,
predator in vicinity)
• General Adaptation Syndrome -
general profile of physiological responses to
stress
Hormonal Responses
to Stress
• 2 main systems involved:
• Autonomic nervous system
• Hypothalamic-pituitary-
adrenocortical system (release of
adrenocorticotrohic hormone;
ACTH)
The Hypothalamic- PituitaryAdrenocortical (HPA) System
p274, McFarland; Fig 15.11
Affect of ACTH on
Adrenal Cortex
• Synthesis and secretion of corticosteroids
• Activation of carbohydrate metabolism
• Regulation of adrenalin production in
adrenal medulla
• Autonomic nervous system and HPA
system closely linked
• Effective response to stressors - coping
Stress Hormones and
Spatial Memory in Rats
• Relevance to understanding human
learning and memory - understanding
learning disabilities in humans
• Stress hormone - corticosterone interferes
with spatial memory skills in rats
• Use of water maze apparatus and learning
trials plus/minus a stressor - electric shock
Water Maze and
Learning Trials
Dugatkin - p 88; Fig 3.16
Shock and spatial Memory
Dugatkin, p 89; Fig 3.17
Summary of Lecture
• Physiological mechanisms - hormones and
behaviour
• Homeostasis
• Environmental influences on behaviour
• Conformers and adaptor thermoregulation, thirst, energy and
nutrients
• Effects of stress on behaviour
Next Lecture
• Drive and motivation
• Behavioural responses to change
in environment: Biological clocks;
Reproductive behaviour; Dormancy:
aestivation and hibernation; Migration;
Lunar and tidal rhythms; Circadian rhythms
and daily routines