Our Test Organism
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Transcript of Our Test Organism
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Our Test OrganismDrosophila simulans
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Trait of Interest
• Red vs. White• Red = advantageous “mutation”• Why are red eyes advantageous?
• Sensory perception• White eyes = reduced mate tracking
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Drosophila chromosome
Red / Whiteeye color gene
“Near” “Far”
22 million bases of DNA
What are we going to look at?• Two markers on X-chromosome
o One close to the gene for white eyeso One far from the gene for white eyes
• Why are we going to look at 2 markers?
22 million bases of DNA
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Microsatellites & Genetic Markers• Sequence differences (aka variation) between
alleles• Usually base pair repeats, insertions, or
deletions• Used for between & within-species
comparisons
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Selective Sweep/HitchhikingBefore sweep After sweep
This is one chromosome from 12 different people. The different colors represent different alleles for that gene.
What happened?
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How are we going to observe & measure genetic variation?
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Step 3: Introduce “advantageous mutation”
Allow mating for several generations
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Anesthetizing fliesFlyNap – Stinky!
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Red male
Red female
White male
White female
Sexing your flies: males have a “black butt”, females have large white abdomen
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How to tell males from females
• Males have black abdomens
• Look close at the tip of the male abdomen and you will see his junk
• Females have rounded abdomens
Female Male
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Sexing
Female Male
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Our Treatments
• Control group:– 5 white-eyed males, 5 white females
• Experimental group:– 5 white-eyed males, 5 white females, 1 red male(“mutant”)
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Started with this…
Control group:5 white-eyed males, 5 white
females
Experimental group:5 white-eyed males, 5 white
females, 1 red male
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Red eyed males Red eyed females
White eyed males White eyed females
Sort into categories and count
After 1 Generation, you will sort the fliesOn a white piece of paper….