Genetics and behavoiur Flashcards
genotype
genetic makeup of an individual
phenotype
-external expression of a genotype
-physical behaviour phenotypes
-modified by the environment
environment
all things external to genes: diet, climate, learning, etc
quantifying behaviour & heritability
-h^2
-0-1
-the proportion of phenotypic variation due to genetic causes
-ie.:
-h^2= genetic variation/phenotypic variation (1)
-h^2= genetic variation/(genetic+environment) (>1)
what evidence is there that behaviour is inherited/instinct
-bird songs, courtship displays, nest building in birds and sows
-breed characteristics of dogs
-individual behavioural differences are inherited
-genes code for both physical phenotype + behavioural phenotype
7 dog groups from common ancestor (grey wolf, canis lupis)
-sporting
-working
-non-sporting
-toy
-herding
-hound
-terrier
study of behavioural inheritance
-cross breeding:
-two closely related species
-offspring show a mix of behaviours
-divergent selection:
-one genetic line
-selected for ‘high’ and ‘low’ traits
-bred multiple generations of ‘high to high’, ‘low to low’
examples and results of crossbreeding lovebirds
-mixed bird songs
-mixed style of nest building
how do genes control behaviour
-changes to CNS:
-during development- expression of neurotrophic factors creates neural pathways
-protein synthesis- enzymes regulate the synthesis of hormones and neurotransmitters
-formation of cell receptors- modulate sensitivity
-epigenetic effects: up-regulation, downregulation
what kind of genes are behaviours controlled by
single or most are by polygenic
single gene behaviours
-controlled by single gene
-ie
-undertaking in bees
-tameness trait in dogs
polygenic behaviours
-more complex
-most behaviours
-controlled by multiple genes/alleles
-complex inheritance: multiple phenotypes
other evidence for ‘tame gene’
-associated with coat colour
-seen in several species
-e.g., the non-agouti gene in rats is associated with tameness
nature vs nurture
genes + environment = phenotype
nature
-born that way
-all in your genes
-genetic determinism inevitability
nurture
-made that way
-product of environment/experience
behaviour traits will evolve if…
1) there is variation in behaviour between individuals
2) the behaviour heritable
3) the behaviour provides a selective advantage
-increased ‘fitness,’ number of offspring
how can we study the evolution of behaviour
-no fossil record as with physical traits
-examine closely related species
-phylogenetic tree: compare innate behaviours e.g., courting rituals, calls, nesting behaviour
-each species has a specific pattern of behaviour
-fixed action patterns
fixed action patterns
-complex action/behaviour
-can be performed without any previous experience
-performance improves with experience
-ie.
-goose rolling an egg
-dog making a bed
-dog burying a bone
sexual selection
-fitness=reproduction
-reproduction involves sex
-sex involves behaviour
-sexual behaviour: played an important role in evolution of physical phenotypes-sexual differences/dimorphism
-specialized behaviours such as: ritualized courtship behaviour + plumage
sexual selection: handicap theory
-healthier males: produce more dramatic plumage
-outcompete others in displays and vocalization
-more attractive=more mates and greater reproduction fitness
domestication and reproduction
-wild animals: reproductive fitness by “Darwinian selection”
-domestic animals: reproductive fitness depends on selection by humans
behavioural changes with domestication
-reduced fear response
-increased social tolerance
-most behaviours are largely unchanged (feral animals survive and reproduce; show all-natural behaviour)
-domestication is flexible (any trait can be selected for but selection can only change so much)
deliberate selection in farm and domestic animals
-until recently there was little deliberate selection for behaviour in farm animals
-inadvertent selection for low fear, ease of handling, maternal care
-deliberate selection was first seen in companion animals
-working dogs selected for behaviour
-e.g. puppy aptitude test for guide dogs
behavioural strategy
-is there optimal behaviour for each species and behaviour
-we need to balance cost vs benefits (greatest benefit for least cost)
-but behavioural traits show large variation
-there is not one optimal behaviour (different behaviours provide different benefits at different times
-diversity ensures that the population can adapt to changing environment (food shortage, drought, forced migration)
