Check your mixed vial, and if it has a decent number of adults, transfer them to a food vial. If you tranferred adults last Tuesday, remove them and count them.
Work on you individual project.
The Human Genome Diversity Project has obtained data on 650,000 single nucleotide polymorphisms (SNPs) in 938 individual humans from 53 populations around the world. These have been made accessible in the HGDP Browser, which assembles data on polymorphism and geographic variation for the SNPs.
Go to the HGDP Browser. Change "show 100kb" to "show 500 kb". Scroll down, and under "Summaries," select "Continent heterozygosity" and "Fst" and deselect "iHS Continent" and "XP-EHH Continent". Then go back to the top and where it says "Search landmark or region," enter "duffy". This is a blood group gene with big geographic variation in allele frequency. You'll then get a display showing the 500 kb around the Duffy gene, with genes marked. The triangles indicate SNPs; red are non-synonymous, green are synonymous, blue are near coding regions but not in them, and yellow and black are non-coding.
One graph represents the Fst for each SNP. This is a measure of geographic variation, with larger Fst values indicating more variation among populations. The graph shows the log of the rank of the Fst value; thus a value of 3 on the graph means that the Fst value is greater than all but one one-thousandth (10-3) of all human SNPs. Click on the triangle for a SNP, and it will show a map with pie charts showing the allele frequencies in different populations. Do this for a few SNPs with low and high Fst values.
The second graph shows the heterozygosity for each continent. High values mean there is a lot of polymorphism in that region.
Some genes (such as Duffy) have a pattern that suggests recent natural selection: high Fst and low polymorphism in some continents. This pattern is consistent with an allele that has recently originated and has rapidly increased in frequency in some areas but not others. The large difference in frequency between the areas results in a high Fst, while the sweep reduces the heterozygosity in that area. There is no statistical test for this pattern, but it is useful as a way of suggesting genes that are worth more intensive study.
Once you've seen what the pattern is like for Duffy, search for the name or abbreviation of the human homologue of the gene you've been working on in flies. If your Drosophila gene doesn't have a human homologue, you could use a gene you're researching in a lab, or one you've heard something about. If you don't have a favorite gene, go to our departmental faculty page, pick out a faculty member, and see what gene they work on.
Once you've found a gene, record which gene it is, and if there are any interesting patterns at or near it. Scroll up or downstream from the gene and if you see a peak of Fst, record what gene is closest to it. Look at SNPs with high Fst and record what the geographic pattern is: is the derived allele most common in Europe and rare elsewhere, is the ancestral allele only found in Australia, etc. See whether there is a pattern of reduced heterozygosity around sites with high Fst.
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This page was last revised October 22, 2010. Its URL is http://udel.edu/~mcdonald/geneticslab16.html