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Biology 3401 - INTRODUCTION
A. - who I am

- where I live - Flemington 207

- when I’m there – Office hours – 9:30 MWF, 9 TTh
B Who’s in the course

- read list

- where stuff is on Web site – Go Through Website

- Labs

- Essay +topics

- Plagiarism

Handouts - Syllabus

- Schedule

General Intro to Course

Course roughly divided into two parts

(1) proximate causes of behaviour

- answer the “how” question about behaviour

- emphasis on mechanisms which govern & generate behaviour patterns

- genes

- hormones

- nerves

- this will go until early October
(2) Ultimate causes - identify & build evolutionary history of behaviour

- how has behaviour evolved

- what purpose or function does it have?

- what is the adaptive context

This entire series of questions will be addressed using scientific method
Question observation

 hypothesis

 prediction

 test

 conclusion

- Expt. on beewolf – wasp -Philanthus triangulum


(1) females nest in sand

(2) - dig burrow - with brood cells

each cell has egg and paralysed bee

(3) female leaves - covers rest with sand and flies to get prey

- 1 Km

(4) returns to nest and opens it
question - how does she find it?

observation - female flies in circle before going to hunt

hypothesis - female is using landmarks

prediction - female will return to landmark to find nest

test - place artificial landmark around nest and move when female is away

result - female orients to moved landmark

conclusion - verify hypothesis
note = never ‘prove’ anything
Humans – been aware of the behaviour of other animals since mankind first appeared

- in context of hunting (being a predator) or not being prey
Greeks – Artistole – introduced concept of a ‘Type” or the perfect form of anything

- notion that variation was an imperfection in the system
This idea persisted until Darwin
- study of beh shared by

Biology *

Psych *

- historically ethol. & psych are related but have different approaches

Ethol. Psych

- Origins on nat hist origins on physiol & med.

- early focus - - early focus

- understanding - understanding

adaptive function causation and motivation

of beh in wild of human beh.

- using animal models

- field based - lab based

- initially more observational - initially empirical

So ... most early ethologists

- naturalists - & observers of nature

- most clergy in Britain

- amateur naturalists - spend lots of time observing & collecting

- in early 19th century in England

- natural history - v. popular

- out of that tradition

- came a more rigorous - theory-based study



- significant contribs

- behaviour as a means for achieving reprod. success

- trace evol. origins

(I would agree: this separates ethol. from psych to this day)

- 3 books

Origin of Species (1859)

- behaviour patterns - complex reflexes that were subject to natural selection

Descent of Man (1871)

- outlined evol. of sex differences

- colour & courtship behaviour of male

- sexual selection

Expression of Emotions in Man & Animals

- comparative study of evol. of expressions & behaviour in humans - comp. with animals.

- emphasized function of beh. in social communication

- comparative method
Darwin’s Contrib.

(1) theory of nat. sel. - let us consider beh. in evol. terms

(2) views on “instinct”

- modifiable units of beh.

- modifiable by evol.

(3) methodology

- comparative method

-continuity between behaviour of humans with other animals
(2) Douglas Spalding

- studies of instinct (inherited beh.)

- looked esp. at instinct in relation to learning

- imprinting

(3) Lloyd Morgan (late 19th)

- experimental

- need for simple objective descriptions

- operational definitions

- controlled experiments - led to dev. of experimental analysis of beh.
(4) Julian Huxley

- one of the first professional zoologists to work on beh.

- studies of birds - systematic field studies that tested Darwin's theories

(B) In USA

- the dev. of ethology

- short circuited - by rise of school of animal behaviourism

- founded by John B. Watson (1910) (d. 1959)

- stressed that animal behaviour - explained as series of learned responses

-respond to the positive reinf. stimul

- conditioning

- lab oriented

- criticized by European ethologists - too divorced from reality
early dev. of ethol. in USA

- delayed due to popularity of behaviour & influence of B.F. Skinner (d. 1990)
(C) Continental Europe

Karl von Frish

- dance language of bees

- major contributions

- comparative neuroethology

- how animals obtain information from env.

- communication systems

- showed colour discrimination - used conditioning techniques

- introduced notion of “Umwelt”

- animal’s perceptual world

- different from ours

- e.g. UV perception in bees

- 1923 - described dance of bees.

Konrad Lorenz

- father of ethology

- discovered & elucidated most of current concepts in ethology

- concerned with observed animals in undisturbed states
- took ideas about ‘instincts’ (often competing ideas) and work out a theor. system for how instincts could work

- could be used in experimentation
Niko Tinbergen

- viewed as co-founder of ethol. (w Lorenz)

- developed field methods

worked on

(1) stimulus control of beh. - (sign stimuli)

- simple models

(2) relationship between beh. & ecology (infl. of habitat on beh.) - e.g. pred. avoid.

(3) adaptive functions of beh.

(eggshell removal, nest spacing )
in 1973 – Lorenz, Tinbergen, von Frisch – joint Nobel Prize

definition -

- simplest definition

- movement (or motor patterns)

- can include

- movements of any body part

- vocalization

- chemical release

- colour change

more realistic definition

- series of coordinated muscular contractions
How is it described and organized

- most often study

- series of temporal sequences

- “motor patterns” or “units”

- complex beh.

- can be produced by simple motor patterns

- all put together

e.g. spider web building

- it is important in all of this

- recognize patterns unambiguously & be able to describe them

- first lab exercise

- about recognition, naming, desc., freq & duration of beh.
but so far

- what I’ve said can be applied to rats in boxes or mating elephants
what we’re dealing with - biological study of behaviour

- ethology - coined by Tinbergen (1963)

- from Greek ‘ethos’ - habit

How do we go about conducting research on animal beh.

- what we’re interested in

HOW? (1) underlying control mech

WHY? (2) function (adaptive signif)
Again go back to Tinbergen - deal with beh. by asking four questions
(A) Proximate causes BIRD SONG

(1) Causation

- neural mechs ?

- hormonal ?

- environmental (external) stimuli

- precedent events

e.g. long theory testosterone singing

spring photopd.

(2) Development (Ontogeny)

- changes with age

- interaction of genes and envir. in determ. beh.

- innate vs. learned (acquired)

e.g. song pattern - learned by nestling during sensitive early phase - hears
(B) Phylogenetic

- how a particular behaviour pattern is expressed in related species

- what this can tell us about evol. within a

All these questions are independent

i.e. can study one without the other

To summarize all this

Genetic mechanisms

Developmental mechanisms

Physiological mechanisms

Neural mechanisms


Gene pool of next generation


Individual survival & reproductive success

Proximate Mechanisms of Behaviour

- behaviour

- can be organized into different time-based events

- molluscs - insect song

- escape

- months - seasonal cycles of behav. (reprod.)

implication here

- beh. - under some kind of variable control mechs

For this part of course - we will look at

(1) responses to external stimuli

(2) role of nervous system

(3) role of endocrine system

(4) role of genome


- when we talk about how to study proximate mechs of behaviour

- looking at how stimuli affect behav.


- (physiologically) any per in the animal’s internal or external environment which results in in membrane physiology of a receptor neuron leading to action potential.


- an absolutely basic concept to all considerations of processing stimuli

- actions of nerves

any nerve cell

- impulses move by the differential movement of K+
Typical neuron

- in this situation

- have a chemical gradient &

electrical in equilibrium

- if measured this

equilibrium - get equilibrium

potential - 65 mV

- resting potential

- if nothing happened to stimulate a nerve

- this resting potential would stay at

- 65 mV forever

- but that’s not what happens

two terms

(1) depolarize - make inside of neuron more positive

(2) hyperpolarize - make inside more negative

- if use small current

- into neuron

small depolarization

- if increase current

action potential


action potential

- brought about by

movement of Na+ ions

- this action potential moves down neuron

- 120 m/s (432 Km/hr)

but eventually - action potential moves to end of neuron

- must cross to another neuron across a space called a SYNAPSE

Presynaptic cell


Postsynaptic cell - action potential

causes release of


- amines

- amino acids

- peptides

- neurotransmitter

- causes depolarization of

postsynaptic cell


- detected via receptors

All receptors - transducers

- change signal in some modality into a nerve impulse

- one of five types







- characterized as

(1) gustatory - taste

(2) olfactory - smell


- all animals differentiate good vs. bad food

- transduction mech.

- depends on kind of taste being encountered

e.g. - salt/sour

- directly influence ion chemicals on receptor membrante

- sweet

- involves 2nd messenger and of chemical reactions which opens ion channel

Olfactory receptors

- can be very sensitive and detect very low concentrations

- e.g. male moths - pheromones

- have 75,000+ receptors/antennae

- small animals olfactory receptors are protected

- inverts - fluid

- vertebrates - mucous


must be dissolved

second messenger

- transduction - complex


- wide range of uses

can respond to - touch

- pressure

- stretching

- sound

- all mecchanoreceptors

- depend on movement of some structure which triggers neuron


- found in inner ear - balance

other kinds

- eardrum

- proprioceptors


- some fish

- modified hair cells

- can sense either

- weak electrical signals from muscles of prey


- gen in generated electrical field


- snakes - sense infrared


- light sensors

- excitable photopigments

- structural in pigments

cascade of reactions

depolarization and action potential

Photo receptors

- can be v. simple

e.g. flatworm - detect dark vs light

- worm avoid bright areas

Insects & Crustaceans

- more complex compound eye

Finally - have vertebrate

- very complex - already know structure

short review - to this point have

(1) method for transmitting nervous signals through body

(2) method and structures for transducing stimuli of all kinds into
one simple e.g. of this illustrates how nerve cells and stimuli are directly related to a behaviour


- escape response

- tail flip when touched ( mechanoreceptors)

in CNS of crayfish

- large nerve cells - giant interneurons GE’s

- one of these - Lateral Giant inerneuron LGI

- demonstrates a correlation between the behaviour and neuron firing

illustrates that LGI is sufficient for response

- hyperpolarize nerve

- block ability to

One problem with all stimuli is that there are so many of them

and an animal must filter out all kinds of stimuli

- this processing can occur peripherally (at receptor level) or centrally (in brain)

e.g. of this - toads preying on worms

- how does a toad recognize prey?

- if go through sequence of events

- if a prey item moves into i ts visual field

- turns toward prey

fixes on it

leans forward

sticks out tongue

question is

- how does toad recognize prey?

Researchers - Ewert in a series of papers

- used the initial orientation response to answer question

- moved cardboard models past toad

- found that choice is made on 2 characteristics

(1) length of object

(2) relationship of length to movement

- specifically

How is toad doing this?

- first level of processing is at

as ‘prey’ enters visual field

- small object will excite receptive field

+ bipolar cells become depolarized

info to

i non-prey enters visual field

- covers a lot of inhibitory field

- cause hyperpolarization & no signal sent

st: at first level

- have selective response to shape characteristics of prey


- in optic tectum

- visual area of brain - integration

- class of neurons - T5(2)

- responds to characteristics that identify ‘prey’

Then through optic tectum & thalamus control motor pattern generators

These motor patterns

motor output

Optic tectum can also tell small vs. large moving object

- large moving object - probably

- leads to generation of another motor pattern flee
Some more e.g.’s
Peripheral Filtering

Audition (Mechanoreceptors)

- for e.g. bats can detect > 100 KHz

moths can detect > 100 KHz

humans - < 20 KHz

There is also an evol/ecol component in this

e.g. bats/moths

- Fullard/Fenton

- all peripheral filters

- share feature of eliminating unnecessary information

Central Filtering

- mechanisms for this - largely unknown

- ethological research - can only suggest the capacity for CNS filtering exists

- need to establish it neurophysiological

how - record from sensor

- if sense organ responds & animal doesn’t behaviour

- suggests some central filtering
- in female canaries

- ventral Hyperstriation (HVc region)

- hypothesized to allow song recognition

- female canary

How does this work in nervous system

Central Pattern Generators (Motor Pattern Generators)

- cluster of pre-motor neurons in CNS

- generate pattern of impulses - pattern of muscle contractor

best studied

- those that regulate locomotion

- esp. among invertebrates

e.g. in book - locust flight

- importance - can fly only if wings move in precise pattern

having central pattern generator

- a good thing

an e.g. where this is not involved

- far simpler kind of beh

- reflex arc

- cockroach

- predator avoidance

- no time for integration


- organize stimuli into 3 major categories

- overlapping

(1) Releasing or triggering stimuli

- stimuli - release a specific behavioural response

- usually more complex beh. than a reflex arc

(2) Orienting stimuli

- change in body position of animal

(3) Priming stimuli

- stimuli affecting animal’s physiological state

- usually longer term

- e.g. photoperiod in spring

- repeated c’ship hormonal changes


Another class of stimuli is recognized


- species specific

- release a reaction that is inherited and not learned

- can be single or multiple ones

simple e.g. in European robin

- red heart

- releases aggressive behaviour in males

but.. tuft of red feathers

works just as well

more complex - bill pecking response of gull chicks
- chick will peck at spot & parent regurgitates

- researchers changed shape, size and colour of beak

- presence and absence of spot

- colour of spot

found that (1) spot needs to be red

(2) bill has to be longer than

SIGN (3) bill has to be certain size rel. to head

STIMULUS (4) bill has to be yellow

Multiple sign stimuli

- often >1 sign stimulates which will evoke a response

& can get summation of stimuli

e.g. male stickleback

- red belly attack

- head down attack

belly & head down more attacks

Response to sign stimuli

- great adaptive significance

- important in situations where it is maladaptive to miss responding to a

- e.g. - pred. avoid

- territorial beh.

What I’ve said so far

- not meant to describe all behav. response

- e.g. often continual learning - aff.

Final point

- special class of sign stimuli


- sign stimuli used in intraspecific communicator

are social signals used in reciprocal communication system

- can be visual


This all leads to a couple of ideas in ethology - hypothesized before neurobiol work

+ the work on toads illustrates it

+ work on sign stimuli illustrates concept but doesn’t say much about how

First idea

Innate Releasing Mechanism

- neural process, triggered by a sign stimulus which preprograms the animal for r eceiving the sign stimulus and mediates a specific behavioral response

how does an IRM work

- no one really knows

but in some e.g.’s we’ve seen so far

- IRM might be recognition of red feathers


- an innate behaviour pattern that is stereotyped, spontaneous and independent of immediate control, genetically coded and independent of learning.

e.g. greylag goose - female on nest

- if take an egg from nest and place it to side

- female will roll it back

- moves head side to side

- anything round will release behaviour

a sign stimulus

- But - if remove egg as female is rolling it

- she keeps going

This is a fixed action pattern.

FAP’s can be strung together to make complex sequences

e.g. sticklebacks

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