TITLE: “Differences in the Signatures of Selection Between the Autosomes and the X Chromosome in Drosophila melanogaster.”
ABSTRACT: Sex chromosomes in Drosophila are found in a hemizygous state in males. Thus, deleterious mutations may be purged more rapidly on the X chromosome than on the autosomes. This purging can result in less available standing variation that can seed adaptation on the X chromosome. Here, we investigate how differences in the recessivity of alleles on the X chromosome versus autosomes impact the mode and tempo of adaptation. Specifically, we test the hypothesis that hard sweeps, in which a single adaptive mutation rises to high frequency, are more common on the X chromosome, while soft sweeps, in which multiple haplotypes rise to high frequency simultaneously, are more common on the autosomes. We analyze D. melanogaster genomic data from two populations, North Carolina, and Zambia, and find evidence that suggests that indeed, hard sweeps are more prevalent on the X chromosome and soft sweeps are more common on the autosomes.
For lunch at 12:30pm with the speaker, please RSVP at qcboffice@lifesci.ucla.edu
