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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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
Black redstarts are short distance migrants, common redstarts are long-distance migrants
Hybrids raised in a common environment, so unlikely that environmental differences account for variation
2 behavioural phenotypes
F2 closer to a 3:1 ratio
Allows researchers to examine the influence of mutations or non-functional genes (knockouts)on behaviour
Knockout mice (lacking fosB) ignore the offspring, provide little or no parental care
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.
What happens if we knock out the Oxt gene that produces oxytocin (an important brain hormone)?
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
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 allow us to examine the influence of environment, while keeping the genetic environment constant
Monozygotic twins (MZ) have the highest correlation in behavioural traits, especially those that share a common environment
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.