Lecture 3 Flashcards
What is Genotype?
Genetic makeup of an individual
What is Phenotype?
External expression of genotype
Physical and behavioural phenotypes
Modified by environment
What is the equation for heritability and what does heritability mean?
H^2 = Genetic variation / Phenotypic variation
OR
H^2 = Genetic variation / (genetic + Environmental variation)
Heritability is the proportion of phenotypic variation due to genetic causes.
H^2 = 0-1
H^2 = 1 means that 100% of the phenotypic variation is due to genetics vise versa.
What evidence is there that behaviour is inherited/intrinsic?
Herding behaviour, a baby that knows how to walk right after birth and can find the udder on its own to eat.
Bird songs, courtship displays, nest building in birds & sows
Individual behavioural differences are what?
Inherited
What 7 breed Canine breed groups do we select?
Sporting
Hounds
Working
Terrier
Toy
Non-sporting
Herding
What is cross breeding?
Breeding two closely related species
Offspring show a mix of behaviours
What is divergent selection?
One genetic line
Selected for ‘high’ and ‘low’ traits
Breed multiple generations
‘high’ to ‘high’, ‘low’ to ‘low’
Select each generation for ‘high’ and ‘low’
performers
What do genes control?
Genes code for a specific protein which then performs certain functions such as hormones, neurotransmitters, receptors.
What changes to the CNS occurs with genes?
During development- expression of neurotoxic factors create neural pathways
Protein synthesis- enzymes regulate synthesis of hormones and neurotransmitters
Formation of cell receptors- modulate sensitivity
What is the epigenetic effect?
Methyl groups can stop gene expression even if the gene is there (like a light switch)
Upregulation, downregulation
What are the 4 phenotypes in ‘Undertaking’ behaviour in bees?
Uncap and remove
Uncap but not remove
Not uncap but will remove
Will neither uncap nor remove
What conclusion did Scott and Fuller (1965) get when they studied the behaviour of several breeds of dogs?
All Basenjis were ‘wild’
All Cocker Spaniels were ‘tame’
f1: All Basenji X C. Spaniel crosses were ‘wild’
f2: 1/4 of f2 generation were ‘tame’
Single gene effect
‘Wild’ trait is dominant; ‘tame’ is
recessive
What is Tameness associated with?
Coat colour
What is Nature VS. Nurture?
Nature: ‘born that way’
it’s all in your genes
‘genetic determinism’, inevitability
Plato, Rene Descartes (1600’s) Views
used to justify racism, ‘Social
Darwinism’
Nurture: ‘made that way’
product of environment/experience
John Locke, BF Skinner (1900’s) All
behaviour is learned, can be
controlled By Punishment and
Reinforcement
What results did the ‘Bright’ and ‘Dull’ rats- divergent selection study find?
1st Conclusion: intelligence is genetic, because this was a controlled system it ignores environment
Later experiments: rats tested in different rearing environments: Restricted, Normal, Enriched
Bright & Dull: both performed well in enriched environment and Both did poorly
in restricted environment.
Gene x Environment interaction: ‘Dull’ rats were more sensitive to environment. Did poorly in Normal environment
Behavioural traits will evolve if…
1) There is variation in behaviour between
individuals
2) The behaviour is heritable
3) The behaviour provides a selective
advantage, increased ‘fitness’, i.e.,
number of offspring
What is the game of life?
To survive
How can the evolution of behaviour be studied?
1) Examine closely related species
2) Phylogenetic tree: compare innate
behaviours e.g., courting rituals, calls,
nesting behaviour
◼ Each species has specific patterns of
behaviour
◼ “Fixed action patterns”
What is Fixed action patterns (FAP)?
FAP is a complex action/behaviour
Can be performed without any previous experience and Performance improves with experience
examples: goose rolling egg, dog making bed, dog burying bone, chick hatching from egg
What is sexual selection?
Fitness = Reproduction
Reproduction involves sex…
Sex involves behaviour…
Sexual behaviour… played important role in evolution of physical phenotypes- sexual differences/ dimorphism
Specialized behaviours: ritualized courtship behaviour & plumage
What is the Handicap theory in sexual selection?
Handicap theory —> energy cost
Healthier males: Produce more dramatic plumage
Outcompete others in displays and vocalizations
More attractive = more mates & greater
reproductive fitness
Reproductive fitness in wild animals is by?
Darwinian selection
Reproductive fitness in domestic animals depends on…?
‘reproductive fitness’ depends on selection by humans
What Behavioural changes are seen with
domestication?
Reduced fear response
Increased social tolerance
Most behaviours are largely unchanged
◼ Nesting in poultry and pigs
◼ Feral animals- survive & reproduce; show all natural behaviours
Domestication is flexible- any trait can be
selected for But- selection can only change ‘so much’
Deliberate behaviour selection was first
seen in what?
companion animals
Is there one ‘optimal behaviour’ for each
species and behaviour?
Balance of costs vs benefits
Optimal territory size: has greatest benefit for least cost
There is not one optimal behaviour, different behaviours provide different
benefits at different times
Within a social species…..
All animals can’t be dominant
Adapt to multiple roles within a group
Diversity enhances group stability/cohesion
Over time…
◼ Different strategies are beneficial
◼ Depending on changes to environment
◼ population density, resources
How has domestication influenced behaviour?
It changes the amount of time the animal performs its natural behaviour
