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Animal Behaviour. BIOL 3100. Artificial Selection. Captive breeding experiment Breed males that start their fall migration late with females that start their fall migration late. Artificial selection.

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artificial selection
Artificial Selection
  • Captive breeding experiment
  • Breed males that start their fall migration late with females that start their fall migration late
artificial selection1
Artificial selection

Implication: If a certain behaviour can be increased or induced over generations through careful breeding (and controlling for environmental influence), it must have a heritable component

slide6

Protective behaviour

Herding

Retreiving

slide9

Black redstarts are short distance migrants, common redstarts are long-distance migrants

  • Period of migratory restlessness varies between species?
  • What about hybrids?

Hybrids

slide10

Hybrids raised in a common environment, so unlikely that environmental differences account for variation

  • Hybrids should have a mix of relevant genes and exhibit intermediate restlessness – exactly what we see above
hybridization
Hybridization

2 behavioural phenotypes

slide12

F1 generation almost all rovers

F2 closer to a 3:1 ratio

mutants and knockouts
Mutants and knockouts

Allows researchers to examine the influence of mutations or non-functional genes (knockouts)on behaviour

slide14

Wild-type mice provide normal parental care to the offspring

Knockout mice (lacking fosB) ignore the offspring, provide little or no parental care

slide15

knockout

wild type

slide16
Why?

fos family genes are expressed in brain regions required for nurturing behaviour

Normally, cues from the pups stimulate the preoptic area of the hypothalamus, which activates the fosB gene and produces the fosB protein

….in the knockout mutants, the fosB protein is not expressed. Thus, the lack of a single protein can have a huge influence on behaviour.

slide17

What happens if we knock out the Oxt gene that produces oxytocin (an important brain hormone)?

slide18

One effect of a lack of oxytocin is that males cannot remember females with whom they have recently interacted.

Each time the knockout male meets the same female he inspects her for as long as he would a new, unfamiliar female

relatedness
Relatedness

Examine the coefficient of relatedness (r), or the proportion of genes shared among individuals

Higher r = share more genes and should thus be more “alike”, assuming the environment is constant

Who shares the most genes ?

twin studies
Twin studies

Twin studies allow us to examine the influence of environment, while keeping the genetic environment constant

slide21

Monozygotic twins (MZ) have the highest correlation in behavioural traits, especially those that share a common environment

the jim twins
The Jim Twins
  • As youngsters, each Jim had a dog named "Toy."
  • Each Jim had been married two times -- the first wives were both called "Linda" and the second wives were both called "Betty."
  • One Jim had named his son "James Allan" and the other Jim had named his son "James Alan."
  • Each twin had driven his light-blue Chevrolet to Pas Grille beach in Florida for family vacations.
  • Both Jims smoked Salem cigarettes and drank Miller Lite beer.
  • Both Jims had at one time held part-time posts as sheriffs.
  • Both were fingernail biters and suffered from migraine headaches.
  • Each Jim enjoyed leaving love notes to his wife throughout the house.
behavioural genomics
Behavioural genomics
  • Examination of the role of genes in the regulation of behaviour
  • Can include examination of specific genes or examination of gene expression patterns (e.g., in the brain) on a genomic scale
candidate gene approach
Candidate Gene Approach
  • Ask: “are specific alleles more common in individuals who display a particular behaviour than those that do not?”
    • Requires a priori knowledge of genes and behaviour
  • Step 1: Compare subject groups that do and do not display the behaviour and examine differences in the candidate gene expression
  • Step 2: Use knock-in or knock-out techniques (like before)
large scale approaches
Large-scale approaches
  • Full-genome sequencing, simultaneously examining thousands of genes at once
  • Can then examine associations between genetic variants and behaviour
slide26

Microarray technology allows us to examine the expression of thousands of genes at once.

Expressed mRNA from the tissue sample hybridizes to complementary DNA on the microarray – lots of mRNA means lots of hybridization and brighter spots. Thus, we can examine the level of expression of thousands of genes at once.