title: Surprising differences in the variability of Y chromosomes in African and cosmopolitan populations of Drosophila melanogaster.
abstract: The nonrecombining Drosophila melanogaster Y chromosome is heterochromatic and has few genes. Despite these limitations, there remains ample opportunity for natural selection to act on the genes that are vital for male fertility and on Y factors that modulate gene expression elsewhere in the genome. Y chromosomes of many organisms have low levels of nucleotide variability, but a formal survey of D. melanogaster Y chromosome variation had yet to be performed. Here we surveyed Y-linked variation in six populations of D. melanogaster spread across the globe. We find surprisingly low levels of variability in African relative to Cosmopolitan (i.e., non-African) populations. While the low levels of Cosmopolitan Y chromosome polymorphism can be explained by the demographic histories of these populations, the staggeringly low polymorphism of African Y chromosomes cannot be explained by demographic history. An explanation that is entirely consistent with the data is that the Y chromosomes of Zimbabwe and Uganda populations have experienced recent selective sweeps. Interestingly, the Zimbabwe and Uganda Y chromosomes differ: in Zimbabwe, a European Y chromosome appears to have swept through the population.
authors.affiliation: Molecular Biology and Genetics, Cornell University, NY 14853, USA. alarracu@bio.rochester.edu
authors.forename: Amanda M
authors.initials: AM
authors.lastname: Larracuente
authors.forename: Andrew G
authors.initials: AG
authors.lastname: Clark
mesh_terms: D000818:Animals; D016000:Cluster Analysis; D004331:Drosophila melanogaster / Q000235:genetics*; D019143:Evolution, Molecular; D005260:Female; D014644:Genetic Variation; D005828:Genetics, Population; D008297:Male; D011110:Polymorphism, Genetic; D011995:Recombination, Genetic; D012641:Selection, Genetic; D014960:X Chromosome; D014998:Y Chromosome