A selective sweep associated with a recent gene transposition in Drosophila miranda.
In Drosophila miranda, a chromosome fusion between the Y chromosome and the autosome corresponding to Muller's element C has created a new sex chromosome system. The chromosome attached to the ancestral Y chromosome is transmitted paternally and hence is not exposed to crossing over. This chromosome, conventionally called the neo-Y, and the homologous neo-X chromosome display many properties of evolving sex chromosomes. We report here the transposition of the exuperantia1 (exu1) locus from a neo-sex chromosome to the ancestral X chromosome of D. miranda. Exu1 is known to have several critical developmental functions, including a male-specific role in spermatogenesis. The ancestral location of exu1 is conserved in the sibling species of D. miranda, as well as in a more distantly related species. The transposition of exu1 can be interpreted as an adaptive fixation, driven by a selective advantage conferred by its effect on dosage compensation. This explanation is supported by the pattern of within-species sequence variation at exu1 and the nearby exu2 locus. The implications of this phenomenon for genome evolution are discussed.
Yi
S
S
Department of Ecology and Evolution, University of Chicago, Chicago, Illinois 60637-1573, USA. soojunyi@midway.uchicago.edu
Charlesworth
B
B
D000483:Alleles; D000818:Animals; D002871:Chromosome Banding; D002874:Chromosome Mapping; D002875:Chromosomes / Q000235:genetics / Q000648:ultrastructure*; D003434:Crossing Over, Genetic; D004330:Drosophila / Q000235:genetics*; D029721:Drosophila Proteins; D004527:Egg Proteins / Q000235:genetics*; D019143:Evolution, Molecular; D005260:Female; D017403:In Situ Hybridization; D019476:Insect Proteins / Q000235:genetics*; D008297:Male; D016601:RNA-Binding Proteins / Q000235:genetics*; D012641:Selection, Genetic; D013045:Species Specificity; D014178:Translocation, Genetic / Q000235:genetics*; D014960:X Chromosome / Q000235:genetics*; D014998:Y Chromosome / Q000648:ultrastructure*
D029721:Drosophila Proteins; D004527:Egg Proteins; D019476:Insect Proteins; D016601:RNA-Binding Proteins; C072067:exu protein, Drosophila