week 05:

Maximum likelihood and leasts squares

More on QTLs

We continue with the example we discussed in class from Ding et al. about fly variants with different male sine song frequencies.

For each backcross fly, we do RNA-seq, and (using a clever model named multiplex shotgun genotyping) you can assign to each allele whether it corresponds to the sim parent or to the mau parent. The mau allele seems to be largely dominant, thus we assign genotypes as “1” if both alleles are sim and “0” otherwise.

Here is the data file w05-homework.dat. Each line corresponds to one backcross male. Each line includes the sine song frequency (first field) followed by the genotypes (1 or 0) for 10 independent loci.

Sanity check: calculate the histogram of sine song frequencies for all backcross males.
For each locus, compare the two hypotheses and decide whether it is linked to the phenotype or not.

The phenotypic data is real (from Ding et al.), the genotypes for the 10 loci are made up.