Our Test Organism Drosophila simulans

Trait of Interest Red vs. White Red = advantageous “mutation” Why are red eyes advantageous? Sensory perception White eyes = reduced mate tracking

Drosophila chromosome Red / White eye 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 eyes o One far from the gene for white eyes Why are we going to look at 2 markers ? 22 million bases of DNA

Microsatellites & Genetic Markers Sequence differences (aka variation) between alleles Usually base pair repeats, insertions, or deletions Used for between & within-species comparisons

Selective Sweep/Hitchhiking Before sweepAfter sweep This is one chromosome from 12 different people. The different colors represent different alleles for that gene. What happened?

How are we going to observe & measure genetic variation?

Step 3: Introduce “advantageous mutation” Allow mating for several generations

Anesthetizing flies FlyNap – Stinky!

Red male Red female White male White female Sexing your flies: males have a “black butt”, females have large white abdomen

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 FemaleMale

Sexing FemaleMale

Our Treatments Control group: – 5 white-eyed males, 5 white females Experimental group: – 5 white-eyed males, 5 white females, 1 red male (“mutant”)

Started with this… Control group: 5 white-eyed males, 5 white females Experimental group: 5 white-eyed males, 5 white females, 1 red male

Red eyed malesRed eyed females White eyed malesWhite eyed females Sort into categories and count After 1 Generation, you will sort the flies On a white piece of paper….