the interaction between genes and environment in shaping behaviour
genes are not the only thing that determines behaviour. The interaction between genes and
environment together determine behaviour.
Genetic basis of behaviour: this should be called the genetic basis for differences in behaviour
There are NO single genes for behaviour per se
Developmental events are subject to environmental effects so that the ultimate results of the same
genetic information can look quite different if the genes are allowed to express themselves in
Sonograms: frequency changes in the songs of birds
usually a balance between environment and genetic differences to give us total variation
any behaviour requires neurotransmitters, muscle movement. A single gene cannot control a
behaviour. But if a gene critical for that behaviour the message being sent.
How can differences in behaviour occur at the single gene level?
Because enzymes don’t work because of spatial abnormailities due to a change in the amino acid
Receptor for a hormone or neurotransmitter has a different binding affinity because of some small
biochemical disease (Parkinson. Uncontrollable shaking, muscles don’t settle after contracting)
Even the abnormality in the production of a single enzyme is likely to have far reaching effects
because most enzymes have multiple functions in the body
White crown sparrows
Common in south America
Thought that different songs were attributed to genetic differences, not the geographical region
But these males were genetically identical from the different regions
Took eggs after they were laid, and waited for them to hatch. Raised them in very different acoustic
circumstances Different groups raised from each group
Each offspring would produce a carbon copy of the frequencies of the songs heard from the males
that they were raised by
Shows learned behaviour, not genetically programmed. Environment is shaping their behaviour
From 1050 days the young males are receptive to the info from the adult ale that they hear. Is
stored and used later to develop the actual dialect
Around 150 days they being matching their song to the info they have stored in their brain
effect of rearing conditions on development of calling behaviour: begging and alarm calls
galah/ pink cockatoo birds. Depending on who you get reared by your song sounds different. They
begging calls more closely resemble the calls of their foster parents than by their biological parents
however if you take the galahs that have been forstered by pink cockatoos, the warning calls are
much more genetically based. The warning or alarm calls stay galah in sound and frequency
social calls more environmentally dependent
warning calls more genetically dependent
nuclei: regions in the brain that are particularly important with habitats with acoustic ability to
develop their song
various areas are connected by nerves and by hormonal secretions
**HVC: higher Vocal Center: development critically important specifically in males to developing
songs. If it does not grow properly, the ability to develop a song.
NCM: caudomedial neostratum:
RA robust nucleus of the arcopallium: to singing
Neural input from one area can affect another area of the brain. Hormones also are transmitted
between these things.
The timing of gene activity as a function of development NO: nirous oxide synthase
ZENK genes upregulates when a young male zegra finsh hears itself sing
Gene activity changes biochemical environment in brain which in turns alter other gene expression
and or activity of neurons
As genes are turned on or turn off and translated into proteins, creates the biochemical
environment in which other genes are expressed.
If an animal is nutritionally deficient, entirely possible that two animals on different diets, with the
same gene set but may end up with different levels of brain functionality. Because the biochemical
conditions in the brain were different they have different levels of brain development
Interaction of gene activity and internal environment on development of behavioursong system of
male and female zebra finches.
Males are more vocalized, have a more complex acoustic job to do in terms of communication. The
parts of the brain related to vocalization are larger and more connected in males than they are in
HVC: growth in males is sustained by estrogen can be mimicked by females by estrogen implants.
Hormone injections can cause the HVC in females to grow similar in size to males
Heritability:h2: ration of (difference in measured behaviour of offspring generation from parental
generation denoted as r) to (difference in behaviour between selected parents from parental
generation and parental generation mean denoted as s)
When h2 is near 1, heritabiluyt is high, when it is near to zero heritability is low
Observed variation among individuals in the parental population id due to genetic differences ,
rather than environmental effects that have modified the expression of the same set of genes
responsible for the behaviour, then the resulting children from the selected parents should aso
differ from the overall parental population by the same amount. In converse, 1h2= amount of
variation due to environmental effects
Evolution by accumulation of small changes
As an analogy, let us say that the most adaptive communication phrase is ME THINKS IT IS A
WEASEL. But the starting point is SWAJS MEIURNZMMVESJDNAY
The probability of getting all of the simultaneous mutations in the sequence in one stem from the
starting point is enourmously small, the probability of each mutation on its own multiplied by that
probabilyt for all of the mutations. But, if in each generation, the sequence which most closely
matches the most adaptive phrase, it is possible for the mutations to accumulate over time so that
the end result can be very different from the starting point.
An example of addative mutation
TYPES OF INFORMATION (LEARNING)
Chemical thermal Mechanical/auditory
Neurons and their operation in controlling behaviour
Receptors: at receiving end. Dentrites
Dentrites pass electrical energy down the neuron as an action potential, to the axons.
Axon terminals attached to another nerve, come close to the dentrites of the next nerve.
Interconnected chain. Conduit for sensory information. Either to CNS or directly to a muscle
Causes voltage in the nerve cell to go up.
Mammal nerve cells normally negative on the inside of the nerve cell. A passing